This is gdb.info, produced by makeinfo version 6.5 from gdb.texinfo.

Copyright (C) 1988-2018 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.

   (a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual.  Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb).                     The GNU debugger.
* gdbserver: (gdb) Server.        The GNU debugging server.
END-INFO-DIR-ENTRY

   This file documents the GNU debugger GDB.

   This is the Tenth Edition, of 'Debugging with GDB: the GNU
Source-Level Debugger' for GDB (GDB) Version 8.1.50.20190122-git.

   Copyright (C) 1988-2018 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.

   (a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual.  Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."


File: gdb.info,  Node: Symbol Tables In Guile,  Next: Breakpoints In Guile,  Prev: Symbols In Guile,  Up: Guile API

23.3.3.18 Symbol table representation in Guile.
...............................................

Access to symbol table data maintained by GDB on the inferior is exposed
to Guile via two objects: '<gdb:sal>' (symtab-and-line) and
'<gdb:symtab>'.  Symbol table and line data for a frame is returned from
the 'frame-find-sal' '<gdb:frame>' procedure.  *Note Frames In Guile::.

   For more information on GDB's symbol table management, see *note
Examining the Symbol Table: Symbols.

   The following symtab-related procedures are provided by the '(gdb)'
module:

 -- Scheme Procedure: symtab? object
     Return '#t' if OBJECT is an object of type '<gdb:symtab>'.
     Otherwise return '#f'.

 -- Scheme Procedure: symtab-valid? symtab
     Return '#t' if the '<gdb:symtab>' object is valid, '#f' if not.  A
     '<gdb:symtab>' object becomes invalid when the symbol table it
     refers to no longer exists in GDB.  All other '<gdb:symtab>'
     procedures will throw an exception if it is invalid at the time the
     procedure is called.

 -- Scheme Procedure: symtab-filename symtab
     Return the symbol table's source filename.

 -- Scheme Procedure: symtab-fullname symtab
     Return the symbol table's source absolute file name.

 -- Scheme Procedure: symtab-objfile symtab
     Return the symbol table's backing object file.  *Note Objfiles In
     Guile::.

 -- Scheme Procedure: symtab-global-block symtab
     Return the global block of the underlying symbol table.  *Note
     Blocks In Guile::.

 -- Scheme Procedure: symtab-static-block symtab
     Return the static block of the underlying symbol table.  *Note
     Blocks In Guile::.

   The following symtab-and-line-related procedures are provided by the
'(gdb)' module:

 -- Scheme Procedure: sal? object
     Return '#t' if OBJECT is an object of type '<gdb:sal>'.  Otherwise
     return '#f'.

 -- Scheme Procedure: sal-valid? sal
     Return '#t' if SAL is valid, '#f' if not.  A '<gdb:sal>' object
     becomes invalid when the Symbol table object it refers to no longer
     exists in GDB.  All other '<gdb:sal>' procedures will throw an
     exception if it is invalid at the time the procedure is called.

 -- Scheme Procedure: sal-symtab sal
     Return the symbol table object ('<gdb:symtab>') for SAL.

 -- Scheme Procedure: sal-line sal
     Return the line number for SAL.

 -- Scheme Procedure: sal-pc sal
     Return the start of the address range occupied by code for SAL.

 -- Scheme Procedure: sal-last sal
     Return the end of the address range occupied by code for SAL.

 -- Scheme Procedure: find-pc-line pc
     Return the '<gdb:sal>' object corresponding to the PC value.  If an
     invalid value of PC is passed as an argument, then the 'symtab' and
     'line' attributes of the returned '<gdb:sal>' object will be '#f'
     and 0 respectively.


File: gdb.info,  Node: Breakpoints In Guile,  Next: Lazy Strings In Guile,  Prev: Symbol Tables In Guile,  Up: Guile API

23.3.3.19 Manipulating breakpoints using Guile
..............................................

Breakpoints in Guile are represented by objects of type
'<gdb:breakpoint>'.  New breakpoints can be created with the
'make-breakpoint' Guile function, and then added to GDB with the
'register-breakpoint!' Guile function.  This two-step approach is taken
to separate out the side-effect of adding the breakpoint to GDB from
'make-breakpoint'.

   Support is also provided to view and manipulate breakpoints created
outside of Guile.

   The following breakpoint-related procedures are provided by the
'(gdb)' module:

 -- Scheme Procedure: make-breakpoint location [#:type type] [#:wp-class
          wp-class] [#:internal internal]
     Create a new breakpoint at LOCATION, a string naming the location
     of the breakpoint, or an expression that defines a watchpoint.  The
     contents can be any location recognized by the 'break' command, or
     in the case of a watchpoint, by the 'watch' command.

     The breakpoint is initially marked as 'invalid'.  The breakpoint is
     not usable until it has been registered with GDB with
     'register-breakpoint!', at which point it becomes 'valid'.  The
     result is the '<gdb:breakpoint>' object representing the
     breakpoint.

     The optional TYPE denotes the breakpoint to create.  This argument
     can be either 'BP_BREAKPOINT' or 'BP_WATCHPOINT', and defaults to
     'BP_BREAKPOINT'.

     The optional WP-CLASS argument defines the class of watchpoint to
     create, if TYPE is 'BP_WATCHPOINT'.  If a watchpoint class is not
     provided, it is assumed to be a 'WP_WRITE' class.

     The optional INTERNAL argument allows the breakpoint to become
     invisible to the user.  The breakpoint will neither be reported
     when registered, nor will it be listed in the output from 'info
     breakpoints' (but will be listed with the 'maint info breakpoints'
     command).  If an internal flag is not provided, the breakpoint is
     visible (non-internal).

     When a watchpoint is created, GDB will try to create a hardware
     assisted watchpoint.  If successful, the type of the watchpoint is
     changed from 'BP_WATCHPOINT' to 'BP_HARDWARE_WATCHPOINT' for
     'WP_WRITE', 'BP_READ_WATCHPOINT' for 'WP_READ', and
     'BP_ACCESS_WATCHPOINT' for 'WP_ACCESS'.  If not successful, the
     type of the watchpoint is left as 'WP_WATCHPOINT'.

     The available types are represented by constants defined in the
     'gdb' module:

     'BP_BREAKPOINT'
          Normal code breakpoint.

     'BP_WATCHPOINT'
          Watchpoint breakpoint.

     'BP_HARDWARE_WATCHPOINT'
          Hardware assisted watchpoint.  This value cannot be specified
          when creating the breakpoint.

     'BP_READ_WATCHPOINT'
          Hardware assisted read watchpoint.  This value cannot be
          specified when creating the breakpoint.

     'BP_ACCESS_WATCHPOINT'
          Hardware assisted access watchpoint.  This value cannot be
          specified when creating the breakpoint.

     The available watchpoint types represented by constants are defined
     in the '(gdb)' module:

     'WP_READ'
          Read only watchpoint.

     'WP_WRITE'
          Write only watchpoint.

     'WP_ACCESS'
          Read/Write watchpoint.

 -- Scheme Procedure: register-breakpoint! breakpoint
     Add BREAKPOINT, a '<gdb:breakpoint>' object, to GDB's list of
     breakpoints.  The breakpoint must have been created with
     'make-breakpoint'.  One cannot register breakpoints that have been
     created outside of Guile.  Once a breakpoint is registered it
     becomes 'valid'.  It is an error to register an already registered
     breakpoint.  The result is unspecified.

 -- Scheme Procedure: delete-breakpoint! breakpoint
     Remove BREAKPOINT from GDB's list of breakpoints.  This also
     invalidates the Guile BREAKPOINT object.  Any further attempt to
     access the object will throw an exception.

     If BREAKPOINT was created from Guile with 'make-breakpoint' it may
     be re-registered with GDB, in which case the breakpoint becomes
     valid again.

 -- Scheme Procedure: breakpoints
     Return a list of all breakpoints.  Each element of the list is a
     '<gdb:breakpoint>' object.

 -- Scheme Procedure: breakpoint? object
     Return '#t' if OBJECT is a '<gdb:breakpoint>' object, and '#f'
     otherwise.

 -- Scheme Procedure: breakpoint-valid? breakpoint
     Return '#t' if BREAKPOINT is valid, '#f' otherwise.  Breakpoints
     created with 'make-breakpoint' are marked as invalid until they are
     registered with GDB with 'register-breakpoint!'.  A
     '<gdb:breakpoint>' object can become invalid if the user deletes
     the breakpoint.  In this case, the object still exists, but the
     underlying breakpoint does not.  In the cases of watchpoint scope,
     the watchpoint remains valid even if execution of the inferior
     leaves the scope of that watchpoint.

 -- Scheme Procedure: breakpoint-number breakpoint
     Return the breakpoint's number -- the identifier used by the user
     to manipulate the breakpoint.

 -- Scheme Procedure: breakpoint-type breakpoint
     Return the breakpoint's type -- the identifier used to determine
     the actual breakpoint type or use-case.

 -- Scheme Procedure: breakpoint-visible? breakpoint
     Return '#t' if the breakpoint is visible to the user when hit, or
     when the 'info breakpoints' command is run.  Otherwise return '#f'.

 -- Scheme Procedure: breakpoint-location breakpoint
     Return the location of the breakpoint, as specified by the user.
     It is a string.  If the breakpoint does not have a location (that
     is, it is a watchpoint) return '#f'.

 -- Scheme Procedure: breakpoint-expression breakpoint
     Return the breakpoint expression, as specified by the user.  It is
     a string.  If the breakpoint does not have an expression (the
     breakpoint is not a watchpoint) return '#f'.

 -- Scheme Procedure: breakpoint-enabled? breakpoint
     Return '#t' if the breakpoint is enabled, and '#f' otherwise.

 -- Scheme Procedure: set-breakpoint-enabled! breakpoint flag
     Set the enabled state of BREAKPOINT to FLAG.  If flag is '#f' it is
     disabled, otherwise it is enabled.

 -- Scheme Procedure: breakpoint-silent? breakpoint
     Return '#t' if the breakpoint is silent, and '#f' otherwise.

     Note that a breakpoint can also be silent if it has commands and
     the first command is 'silent'.  This is not reported by the
     'silent' attribute.

 -- Scheme Procedure: set-breakpoint-silent! breakpoint flag
     Set the silent state of BREAKPOINT to FLAG.  If flag is '#f' the
     breakpoint is made silent, otherwise it is made non-silent (or
     noisy).

 -- Scheme Procedure: breakpoint-ignore-count breakpoint
     Return the ignore count for BREAKPOINT.

 -- Scheme Procedure: set-breakpoint-ignore-count! breakpoint count
     Set the ignore count for BREAKPOINT to COUNT.

 -- Scheme Procedure: breakpoint-hit-count breakpoint
     Return hit count of BREAKPOINT.

 -- Scheme Procedure: set-breakpoint-hit-count! breakpoint count
     Set the hit count of BREAKPOINT to COUNT.  At present, COUNT must
     be zero.

 -- Scheme Procedure: breakpoint-thread breakpoint
     Return the global-thread-id for thread-specific breakpoint
     BREAKPOINT.  Return #f if BREAKPOINT is not thread-specific.

 -- Scheme Procedure: set-breakpoint-thread! breakpoint
          global-thread-id|#f
     Set the thread-id for BREAKPOINT to GLOBAL-THREAD-ID If set to
     '#f', the breakpoint is no longer thread-specific.

 -- Scheme Procedure: breakpoint-task breakpoint
     If the breakpoint is Ada task-specific, return the Ada task id.  If
     the breakpoint is not task-specific (or the underlying language is
     not Ada), return '#f'.

 -- Scheme Procedure: set-breakpoint-task! breakpoint task
     Set the Ada task of BREAKPOINT to TASK.  If set to '#f', the
     breakpoint is no longer task-specific.

 -- Scheme Procedure: breakpoint-condition breakpoint
     Return the condition of BREAKPOINT, as specified by the user.  It
     is a string.  If there is no condition, return '#f'.

 -- Scheme Procedure: set-breakpoint-condition! breakpoint condition
     Set the condition of BREAKPOINT to CONDITION, which must be a
     string.  If set to '#f' then the breakpoint becomes unconditional.

 -- Scheme Procedure: breakpoint-stop breakpoint
     Return the stop predicate of BREAKPOINT.  See
     'set-breakpoint-stop!' below in this section.

 -- Scheme Procedure: set-breakpoint-stop! breakpoint procedure|#f
     Set the stop predicate of BREAKPOINT.  The predicate PROCEDURE
     takes one argument: the <gdb:breakpoint> object.  If this predicate
     is set to a procedure then it is invoked whenever the inferior
     reaches this breakpoint.  If it returns '#t', or any non-'#f'
     value, then the inferior is stopped, otherwise the inferior will
     continue.

     If there are multiple breakpoints at the same location with a
     'stop' predicate, each one will be called regardless of the return
     status of the previous.  This ensures that all 'stop' predicates
     have a chance to execute at that location.  In this scenario if one
     of the methods returns '#t' but the others return '#f', the
     inferior will still be stopped.

     You should not alter the execution state of the inferior (i.e.,
     step, next, etc.), alter the current frame context (i.e., change
     the current active frame), or alter, add or delete any breakpoint.
     As a general rule, you should not alter any data within GDB or the
     inferior at this time.

     Example 'stop' implementation:

          (define (my-stop? bkpt)
            (let ((int-val (parse-and-eval "foo")))
              (value=? int-val 3)))
          (define bkpt (make-breakpoint "main.c:42"))
          (register-breakpoint! bkpt)
          (set-breakpoint-stop! bkpt my-stop?)

 -- Scheme Procedure: breakpoint-commands breakpoint
     Return the commands attached to BREAKPOINT as a string, or '#f' if
     there are none.


File: gdb.info,  Node: Lazy Strings In Guile,  Next: Architectures In Guile,  Prev: Breakpoints In Guile,  Up: Guile API

23.3.3.20 Guile representation of lazy strings.
...............................................

A "lazy string" is a string whose contents is not retrieved or encoded
until it is needed.

   A '<gdb:lazy-string>' is represented in GDB as an 'address' that
points to a region of memory, an 'encoding' that will be used to encode
that region of memory, and a 'length' to delimit the region of memory
that represents the string.  The difference between a
'<gdb:lazy-string>' and a string wrapped within a '<gdb:value>' is that
a '<gdb:lazy-string>' will be treated differently by GDB when printing.
A '<gdb:lazy-string>' is retrieved and encoded during printing, while a
'<gdb:value>' wrapping a string is immediately retrieved and encoded on
creation.

   The following lazy-string-related procedures are provided by the
'(gdb)' module:

 -- Scheme Procedure: lazy-string? object
     Return '#t' if OBJECT is an object of type '<gdb:lazy-string>'.
     Otherwise return '#f'.

 -- Scheme Procedure: lazy-string-address lazy-sring
     Return the address of LAZY-STRING.

 -- Scheme Procedure: lazy-string-length lazy-string
     Return the length of LAZY-STRING in characters.  If the length is
     -1, then the string will be fetched and encoded up to the first
     null of appropriate width.

 -- Scheme Procedure: lazy-string-encoding lazy-string
     Return the encoding that will be applied to LAZY-STRING when the
     string is printed by GDB.  If the encoding is not set, or contains
     an empty string, then GDB will select the most appropriate encoding
     when the string is printed.

 -- Scheme Procedure: lazy-string-type lazy-string
     Return the type that is represented by LAZY-STRING's type.  For a
     lazy string this is a pointer or array type.  To resolve this to
     the lazy string's character type, use 'type-target-type'.  *Note
     Types In Guile::.

 -- Scheme Procedure: lazy-string->value lazy-string
     Convert the '<gdb:lazy-string>' to a '<gdb:value>'.  This value
     will point to the string in memory, but will lose all the delayed
     retrieval, encoding and handling that GDB applies to a
     '<gdb:lazy-string>'.


File: gdb.info,  Node: Architectures In Guile,  Next: Disassembly In Guile,  Prev: Lazy Strings In Guile,  Up: Guile API

23.3.3.21 Guile representation of architectures
...............................................

GDB uses architecture specific parameters and artifacts in a number of
its various computations.  An architecture is represented by an instance
of the '<gdb:arch>' class.

   The following architecture-related procedures are provided by the
'(gdb)' module:

 -- Scheme Procedure: arch? object
     Return '#t' if OBJECT is an object of type '<gdb:arch>'.  Otherwise
     return '#f'.

 -- Scheme Procedure: current-arch
     Return the current architecture as a '<gdb:arch>' object.

 -- Scheme Procedure: arch-name arch
     Return the name (string value) of '<gdb:arch>' ARCH.

 -- Scheme Procedure: arch-charset arch
     Return name of target character set of '<gdb:arch>' ARCH.

 -- Scheme Procedure: arch-wide-charset
     Return name of target wide character set of '<gdb:arch>' ARCH.

   Each architecture provides a set of predefined types, obtained by the
following functions.

 -- Scheme Procedure: arch-void-type arch
     Return the '<gdb:type>' object for a 'void' type of architecture
     ARCH.

 -- Scheme Procedure: arch-char-type arch
     Return the '<gdb:type>' object for a 'char' type of architecture
     ARCH.

 -- Scheme Procedure: arch-short-type arch
     Return the '<gdb:type>' object for a 'short' type of architecture
     ARCH.

 -- Scheme Procedure: arch-int-type arch
     Return the '<gdb:type>' object for an 'int' type of architecture
     ARCH.

 -- Scheme Procedure: arch-long-type arch
     Return the '<gdb:type>' object for a 'long' type of architecture
     ARCH.

 -- Scheme Procedure: arch-schar-type arch
     Return the '<gdb:type>' object for a 'signed char' type of
     architecture ARCH.

 -- Scheme Procedure: arch-uchar-type arch
     Return the '<gdb:type>' object for an 'unsigned char' type of
     architecture ARCH.

 -- Scheme Procedure: arch-ushort-type arch
     Return the '<gdb:type>' object for an 'unsigned short' type of
     architecture ARCH.

 -- Scheme Procedure: arch-uint-type arch
     Return the '<gdb:type>' object for an 'unsigned int' type of
     architecture ARCH.

 -- Scheme Procedure: arch-ulong-type arch
     Return the '<gdb:type>' object for an 'unsigned long' type of
     architecture ARCH.

 -- Scheme Procedure: arch-float-type arch
     Return the '<gdb:type>' object for a 'float' type of architecture
     ARCH.

 -- Scheme Procedure: arch-double-type arch
     Return the '<gdb:type>' object for a 'double' type of architecture
     ARCH.

 -- Scheme Procedure: arch-longdouble-type arch
     Return the '<gdb:type>' object for a 'long double' type of
     architecture ARCH.

 -- Scheme Procedure: arch-bool-type arch
     Return the '<gdb:type>' object for a 'bool' type of architecture
     ARCH.

 -- Scheme Procedure: arch-longlong-type arch
     Return the '<gdb:type>' object for a 'long long' type of
     architecture ARCH.

 -- Scheme Procedure: arch-ulonglong-type arch
     Return the '<gdb:type>' object for an 'unsigned long long' type of
     architecture ARCH.

 -- Scheme Procedure: arch-int8-type arch
     Return the '<gdb:type>' object for an 'int8' type of architecture
     ARCH.

 -- Scheme Procedure: arch-uint8-type arch
     Return the '<gdb:type>' object for a 'uint8' type of architecture
     ARCH.

 -- Scheme Procedure: arch-int16-type arch
     Return the '<gdb:type>' object for an 'int16' type of architecture
     ARCH.

 -- Scheme Procedure: arch-uint16-type arch
     Return the '<gdb:type>' object for a 'uint16' type of architecture
     ARCH.

 -- Scheme Procedure: arch-int32-type arch
     Return the '<gdb:type>' object for an 'int32' type of architecture
     ARCH.

 -- Scheme Procedure: arch-uint32-type arch
     Return the '<gdb:type>' object for a 'uint32' type of architecture
     ARCH.

 -- Scheme Procedure: arch-int64-type arch
     Return the '<gdb:type>' object for an 'int64' type of architecture
     ARCH.

 -- Scheme Procedure: arch-uint64-type arch
     Return the '<gdb:type>' object for a 'uint64' type of architecture
     ARCH.

   Example:

     (gdb) guile (type-name (arch-uchar-type (current-arch)))
     "unsigned char"


File: gdb.info,  Node: Disassembly In Guile,  Next: I/O Ports in Guile,  Prev: Architectures In Guile,  Up: Guile API

23.3.3.22 Disassembly In Guile
..............................

The disassembler can be invoked from Scheme code.  Furthermore, the
disassembler can take a Guile port as input, allowing one to disassemble
from any source, and not just target memory.

 -- Scheme Procedure: arch-disassemble arch start-pc [#:port port]
          [#:offset offset] [#:size size] [#:count count]
     Return a list of disassembled instructions starting from the memory
     address START-PC.

     The optional argument PORT specifies the input port to read bytes
     from.  If PORT is '#f' then bytes are read from target memory.

     The optional argument OFFSET specifies the address offset of the
     first byte in PORT.  This is useful, for example, when PORT
     specifies a 'bytevector' and you want the bytevector to be
     disassembled as if it came from that address.  The START-PC passed
     to the reader for PORT is offset by the same amount.

     Example:
          (gdb) guile (use-modules (rnrs io ports))
          (gdb) guile (define pc (value->integer (parse-and-eval "$pc")))
          (gdb) guile (define mem (open-memory #:start pc))
          (gdb) guile (define bv (get-bytevector-n mem 10))
          (gdb) guile (define bv-port (open-bytevector-input-port bv))
          (gdb) guile (define arch (current-arch))
          (gdb) guile (arch-disassemble arch pc #:port bv-port #:offset pc)
          (((address . 4195516) (asm . "mov    $0x4005c8,%edi") (length . 5)))

     The optional arguments SIZE and COUNT determine the number of
     instructions in the returned list.  If either SIZE or COUNT is
     specified as zero, then no instructions are disassembled and an
     empty list is returned.  If both the optional arguments SIZE and
     COUNT are specified, then a list of at most COUNT disassembled
     instructions whose start address falls in the closed memory address
     interval from START-PC to (START-PC + SIZE - 1) are returned.  If
     SIZE is not specified, but COUNT is specified, then COUNT number of
     instructions starting from the address START-PC are returned.  If
     COUNT is not specified but SIZE is specified, then all instructions
     whose start address falls in the closed memory address interval
     from START-PC to (START-PC + SIZE - 1) are returned.  If neither
     SIZE nor COUNT are specified, then a single instruction at START-PC
     is returned.

     Each element of the returned list is an alist (associative list)
     with the following keys:

     'address'
          The value corresponding to this key is a Guile integer of the
          memory address of the instruction.

     'asm'
          The value corresponding to this key is a string value which
          represents the instruction with assembly language mnemonics.
          The assembly language flavor used is the same as that
          specified by the current CLI variable 'disassembly-flavor'.
          *Note Machine Code::.

     'length'
          The value corresponding to this key is the length of the
          instruction in bytes.


File: gdb.info,  Node: I/O Ports in Guile,  Next: Memory Ports in Guile,  Prev: Disassembly In Guile,  Up: Guile API

23.3.3.23 I/O Ports in Guile
............................

 -- Scheme Procedure: input-port
     Return GDB's input port as a Guile port object.

 -- Scheme Procedure: output-port
     Return GDB's output port as a Guile port object.

 -- Scheme Procedure: error-port
     Return GDB's error port as a Guile port object.

 -- Scheme Procedure: stdio-port? object
     Return '#t' if OBJECT is a GDB stdio port.  Otherwise return '#f'.


File: gdb.info,  Node: Memory Ports in Guile,  Next: Iterators In Guile,  Prev: I/O Ports in Guile,  Up: Guile API

23.3.3.24 Memory Ports in Guile
...............................

GDB provides a 'port' interface to target memory.  This allows Guile
code to read/write target memory using Guile's port and bytevector
functionality.  The main routine is 'open-memory' which returns a port
object.  One can then read/write memory using that object.

 -- Scheme Procedure: open-memory [#:mode mode] [#:start address]
          [#:size size]
     Return a port object that can be used for reading and writing
     memory.  The port will be open according to MODE, which is the
     standard mode argument to Guile port open routines, except that the
     '"a"' and '"l"' modes are not supported.  *Note (guile)File
     Ports::.  The '"b"' (binary) character may be present, but is
     ignored: memory ports are binary only.  If '"0"' is appended then
     the port is marked as unbuffered.  The default is '"r"', read-only
     and buffered.

     The chunk of memory that can be accessed can be bounded.  If both
     START and SIZE are unspecified, all of memory can be accessed.  If
     only START is specified, all of memory from that point on can be
     accessed.  If only SIZE if specified, all memory in the range
     [0,SIZE) can be accessed.  If both are specified, all memory in the
     rane [START,START+SIZE) can be accessed.

 -- Scheme Procedure: memory-port?
     Return '#t' if OBJECT is an object of type '<gdb:memory-port>'.
     Otherwise return '#f'.

 -- Scheme Procedure: memory-port-range memory-port
     Return the range of '<gdb:memory-port>' MEMORY-PORT as a list of
     two elements: '(start end)'.  The range is START to END inclusive.

 -- Scheme Procedure: memory-port-read-buffer-size memory-port
     Return the size of the read buffer of '<gdb:memory-port>'
     MEMORY-PORT.

 -- Scheme Procedure: set-memory-port-read-buffer-size! memory-port size
     Set the size of the read buffer of '<gdb:memory-port>' MEMORY-PORT
     to SIZE.  The result is unspecified.

 -- Scheme Procedure: memory-port-write-buffer-size memory-port
     Return the size of the write buffer of '<gdb:memory-port>'
     MEMORY-PORT.

 -- Scheme Procedure: set-memory-port-write-buffer-size! memory-port
          size
     Set the size of the write buffer of '<gdb:memory-port>' MEMORY-PORT
     to SIZE.  The result is unspecified.

   A memory port is closed like any other port, with 'close-port'.

   Combined with Guile's 'bytevectors', memory ports provide a lot of
utility.  For example, to fill a buffer of 10 integers in memory, one
can do something like the following.

     ;; In the program: int buffer[10];
     (use-modules (rnrs bytevectors))
     (use-modules (rnrs io ports))
     (define addr (parse-and-eval "buffer"))
     (define n 10)
     (define byte-size (* n 4))
     (define mem-port (open-memory #:mode "r+" #:start
                                   (value->integer addr) #:size byte-size))
     (define byte-vec (make-bytevector byte-size))
     (do ((i 0 (+ i 1)))
         ((>= i n))
         (bytevector-s32-native-set! byte-vec (* i 4) (* i 42)))
     (put-bytevector mem-port byte-vec)
     (close-port mem-port)


File: gdb.info,  Node: Iterators In Guile,  Prev: Memory Ports in Guile,  Up: Guile API

23.3.3.25 Iterators In Guile
............................

A simple iterator facility is provided to allow, for example, iterating
over the set of program symbols without having to first construct a list
of all of them.  A useful contribution would be to add support for SRFI
41 and SRFI 45.

 -- Scheme Procedure: make-iterator object progress next!
     A '<gdb:iterator>' object is constructed with the 'make-iterator'
     procedure.  It takes three arguments: the object to be iterated
     over, an object to record the progress of the iteration, and a
     procedure to return the next element in the iteration, or an
     implementation chosen value to denote the end of iteration.

     By convention, end of iteration is marked with
     '(end-of-iteration)', and may be tested with the
     'end-of-iteration?' predicate.  The result of '(end-of-iteration)'
     is chosen so that it is not otherwise used by the '(gdb)' module.
     If you are using '<gdb:iterator>' in your own code it is your
     responsibility to maintain this invariant.

     A trivial example for illustration's sake:

          (use-modules (gdb iterator))
          (define my-list (list 1 2 3))
          (define iter
            (make-iterator my-list my-list
                           (lambda (iter)
                             (let ((l (iterator-progress iter)))
                               (if (eq? l '())
                                   (end-of-iteration)
                                   (begin
                                     (set-iterator-progress! iter (cdr l))
                                     (car l)))))))

     Here is a slightly more realistic example, which computes a list of
     all the functions in 'my-global-block'.

          (use-modules (gdb iterator))
          (define this-sal (find-pc-line (frame-pc (selected-frame))))
          (define this-symtab (sal-symtab this-sal))
          (define this-global-block (symtab-global-block this-symtab))
          (define syms-iter (make-block-symbols-iterator this-global-block))
          (define functions (iterator-filter symbol-function? syms-iter))

 -- Scheme Procedure: iterator? object
     Return '#t' if OBJECT is a '<gdb:iterator>' object.  Otherwise
     return '#f'.

 -- Scheme Procedure: iterator-object iterator
     Return the first argument that was passed to 'make-iterator'.  This
     is the object being iterated over.

 -- Scheme Procedure: iterator-progress iterator
     Return the object tracking iteration progress.

 -- Scheme Procedure: set-iterator-progress! iterator new-value
     Set the object tracking iteration progress.

 -- Scheme Procedure: iterator-next! iterator
     Invoke the procedure that was the third argument to
     'make-iterator', passing it one argument, the '<gdb:iterator>'
     object.  The result is either the next element in the iteration, or
     an end marker as implemented by the 'next!' procedure.  By
     convention the end marker is the result of '(end-of-iteration)'.

 -- Scheme Procedure: end-of-iteration
     Return the Scheme object that denotes end of iteration.

 -- Scheme Procedure: end-of-iteration? object
     Return '#t' if OBJECT is the end of iteration marker.  Otherwise
     return '#f'.

   These functions are provided by the '(gdb iterator)' module to assist
in using iterators.

 -- Scheme Procedure: make-list-iterator list
     Return a '<gdb:iterator>' object that will iterate over LIST.

 -- Scheme Procedure: iterator->list iterator
     Return the elements pointed to by ITERATOR as a list.

 -- Scheme Procedure: iterator-map proc iterator
     Return the list of objects obtained by applying PROC to the object
     pointed to by ITERATOR and to each subsequent object.

 -- Scheme Procedure: iterator-for-each proc iterator
     Apply PROC to each element pointed to by ITERATOR.  The result is
     unspecified.

 -- Scheme Procedure: iterator-filter pred iterator
     Return the list of elements pointed to by ITERATOR that satisfy
     PRED.

 -- Scheme Procedure: iterator-until pred iterator
     Run ITERATOR until the result of '(pred element)' is true and
     return that as the result.  Otherwise return '#f'.


File: gdb.info,  Node: Guile Auto-loading,  Next: Guile Modules,  Prev: Guile API,  Up: Guile

23.3.4 Guile Auto-loading
-------------------------

When a new object file is read (for example, due to the 'file' command,
or because the inferior has loaded a shared library), GDB will look for
Guile support scripts in two ways: 'OBJFILE-gdb.scm' and the
'.debug_gdb_scripts' section.  *Note Auto-loading extensions::.

   The auto-loading feature is useful for supplying application-specific
debugging commands and scripts.

   Auto-loading can be enabled or disabled, and the list of auto-loaded
scripts can be printed.

'set auto-load guile-scripts [on|off]'
     Enable or disable the auto-loading of Guile scripts.

'show auto-load guile-scripts'
     Show whether auto-loading of Guile scripts is enabled or disabled.

'info auto-load guile-scripts [REGEXP]'
     Print the list of all Guile scripts that GDB auto-loaded.

     Also printed is the list of Guile scripts that were mentioned in
     the '.debug_gdb_scripts' section and were not found.  This is
     useful because their names are not printed when GDB tries to load
     them and fails.  There may be many of them, and printing an error
     message for each one is problematic.

     If REGEXP is supplied only Guile scripts with matching names are
     printed.

     Example:

          (gdb) info auto-load guile-scripts
          Loaded Script
          Yes    scm-section-script.scm
                 full name: /tmp/scm-section-script.scm
          No     my-foo-pretty-printers.scm

   When reading an auto-loaded file, GDB sets the "current objfile".
This is available via the 'current-objfile' procedure (*note Objfiles In
Guile::).  This can be useful for registering objfile-specific
pretty-printers.


File: gdb.info,  Node: Guile Modules,  Prev: Guile Auto-loading,  Up: Guile

23.3.5 Guile Modules
--------------------

GDB comes with several modules to assist writing Guile code.

* Menu:

* Guile Printing Module::  Building and registering pretty-printers
* Guile Types Module::     Utilities for working with types


File: gdb.info,  Node: Guile Printing Module,  Next: Guile Types Module,  Up: Guile Modules

23.3.5.1 Guile Printing Module
..............................

This module provides a collection of utilities for working with
pretty-printers.

   Usage:

     (use-modules (gdb printing))

 -- Scheme Procedure: prepend-pretty-printer! object printer
     Add PRINTER to the front of the list of pretty-printers for OBJECT.
     The OBJECT must either be a '<gdb:objfile>' object, or '#f' in
     which case PRINTER is added to the global list of printers.

 -- Scheme Procecure: append-pretty-printer! object printer
     Add PRINTER to the end of the list of pretty-printers for OBJECT.
     The OBJECT must either be a '<gdb:objfile>' object, or '#f' in
     which case PRINTER is added to the global list of printers.


File: gdb.info,  Node: Guile Types Module,  Prev: Guile Printing Module,  Up: Guile Modules

23.3.5.2 Guile Types Module
...........................

This module provides a collection of utilities for working with
'<gdb:type>' objects.

   Usage:

     (use-modules (gdb types))

 -- Scheme Procedure: get-basic-type type
     Return TYPE with const and volatile qualifiers stripped, and with
     typedefs and C++ references converted to the underlying type.

     C++ example:

          typedef const int const_int;
          const_int foo (3);
          const_int& foo_ref (foo);
          int main () { return 0; }

     Then in gdb:

          (gdb) start
          (gdb) guile (use-modules (gdb) (gdb types))
          (gdb) guile (define foo-ref (parse-and-eval "foo_ref"))
          (gdb) guile (get-basic-type (value-type foo-ref))
          int

 -- Scheme Procedure: type-has-field-deep? type field
     Return '#t' if TYPE, assumed to be a type with fields (e.g., a
     structure or union), has field FIELD.  Otherwise return '#f'.  This
     searches baseclasses, whereas 'type-has-field?' does not.

 -- Scheme Procedure: make-enum-hashtable enum-type
     Return a Guile hash table produced from ENUM-TYPE.  Elements in the
     hash table are referenced with 'hashq-ref'.


File: gdb.info,  Node: Auto-loading extensions,  Next: Multiple Extension Languages,  Prev: Guile,  Up: Extending GDB

23.4 Auto-loading extensions
============================

GDB provides two mechanisms for automatically loading extensions when a
new object file is read (for example, due to the 'file' command, or
because the inferior has loaded a shared library): 'OBJFILE-gdb.EXT' and
the '.debug_gdb_scripts' section of modern file formats like ELF.

* Menu:

* objfile-gdb.ext file: objfile-gdbdotext file.  The 'OBJFILE-gdb.EXT' file
* .debug_gdb_scripts section: dotdebug_gdb_scripts section.  The '.debug_gdb_scripts' section
* Which flavor to choose?::

   The auto-loading feature is useful for supplying application-specific
debugging commands and features.

   Auto-loading can be enabled or disabled, and the list of auto-loaded
scripts can be printed.  See the 'auto-loading' section of each
extension language for more information.  For GDB command files see
*note Auto-loading sequences::.  For Python files see *note Python
Auto-loading::.

   Note that loading of this script file also requires accordingly
configured 'auto-load safe-path' (*note Auto-loading safe path::).


File: gdb.info,  Node: objfile-gdbdotext file,  Next: dotdebug_gdb_scripts section,  Up: Auto-loading extensions

23.4.1 The 'OBJFILE-gdb.EXT' file
---------------------------------

When a new object file is read, GDB looks for a file named
'OBJFILE-gdb.EXT' (we call it SCRIPT-NAME below), where OBJFILE is the
object file's name and where EXT is the file extension for the extension
language:

'OBJFILE-gdb.gdb'
     GDB's own command language
'OBJFILE-gdb.py'
     Python
'OBJFILE-gdb.scm'
     Guile

   SCRIPT-NAME is formed by ensuring that the file name of OBJFILE is
absolute, following all symlinks, and resolving '.' and '..' components,
and appending the '-gdb.EXT' suffix.  If this file exists and is
readable, GDB will evaluate it as a script in the specified extension
language.

   If this file does not exist, then GDB will look for SCRIPT-NAME file
in all of the directories as specified below.

   Note that loading of these files requires an accordingly configured
'auto-load safe-path' (*note Auto-loading safe path::).

   For object files using '.exe' suffix GDB tries to load first the
scripts normally according to its '.exe' filename.  But if no scripts
are found GDB also tries script filenames matching the object file
without its '.exe' suffix.  This '.exe' stripping is case insensitive
and it is attempted on any platform.  This makes the script filenames
compatible between Unix and MS-Windows hosts.

'set auto-load scripts-directory [DIRECTORIES]'
     Control GDB auto-loaded scripts location.  Multiple directory
     entries may be delimited by the host platform path separator in use
     (':' on Unix, ';' on MS-Windows and MS-DOS).

     Each entry here needs to be covered also by the security setting
     'set auto-load safe-path' (*note set auto-load safe-path::).

     This variable defaults to '$debugdir:$datadir/auto-load'.  The
     default 'set auto-load safe-path' value can be also overriden by
     GDB configuration option '--with-auto-load-dir'.

     Any reference to '$debugdir' will get replaced by
     DEBUG-FILE-DIRECTORY value (*note Separate Debug Files::) and any
     reference to '$datadir' will get replaced by DATA-DIRECTORY which
     is determined at GDB startup (*note Data Files::).  '$debugdir' and
     '$datadir' must be placed as a directory component -- either alone
     or delimited by '/' or '\' directory separators, depending on the
     host platform.

     The list of directories uses path separator (':' on GNU and Unix
     systems, ';' on MS-Windows and MS-DOS) to separate directories,
     similarly to the 'PATH' environment variable.

'show auto-load scripts-directory'
     Show GDB auto-loaded scripts location.

'add-auto-load-scripts-directory [DIRECTORIES...]'
     Add an entry (or list of entries) to the list of auto-loaded
     scripts locations.  Multiple entries may be delimited by the host
     platform path separator in use.

   GDB does not track which files it has already auto-loaded this way.
GDB will load the associated script every time the corresponding OBJFILE
is opened.  So your '-gdb.EXT' file should be careful to avoid errors if
it is evaluated more than once.


File: gdb.info,  Node: dotdebug_gdb_scripts section,  Next: Which flavor to choose?,  Prev: objfile-gdbdotext file,  Up: Auto-loading extensions

23.4.2 The '.debug_gdb_scripts' section
---------------------------------------

For systems using file formats like ELF and COFF, when GDB loads a new
object file it will look for a special section named
'.debug_gdb_scripts'.  If this section exists, its contents is a list of
null-terminated entries specifying scripts to load.  Each entry begins
with a non-null prefix byte that specifies the kind of entry, typically
the extension language and whether the script is in a file or inlined in
'.debug_gdb_scripts'.

   The following entries are supported:

'SECTION_SCRIPT_ID_PYTHON_FILE = 1'
'SECTION_SCRIPT_ID_SCHEME_FILE = 3'
'SECTION_SCRIPT_ID_PYTHON_TEXT = 4'
'SECTION_SCRIPT_ID_SCHEME_TEXT = 6'

23.4.2.1 Script File Entries
............................

If the entry specifies a file, GDB will look for the file first in the
current directory and then along the source search path (*note
Specifying Source Directories: Source Path.), except that '$cdir' is not
searched, since the compilation directory is not relevant to scripts.

   File entries can be placed in section '.debug_gdb_scripts' with, for
example, this GCC macro for Python scripts.

     /* Note: The "MS" section flags are to remove duplicates.  */
     #define DEFINE_GDB_PY_SCRIPT(script_name) \
       asm("\
     .pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n\
     .byte 1 /* Python */\n\
     .asciz \"" script_name "\"\n\
     .popsection \n\
     ");

For Guile scripts, replace '.byte 1' with '.byte 3'.  Then one can
reference the macro in a header or source file like this:

     DEFINE_GDB_PY_SCRIPT ("my-app-scripts.py")

   The script name may include directories if desired.

   Note that loading of this script file also requires accordingly
configured 'auto-load safe-path' (*note Auto-loading safe path::).

   If the macro invocation is put in a header, any application or
library using this header will get a reference to the specified script,
and with the use of '"MS"' attributes on the section, the linker will
remove duplicates.

23.4.2.2 Script Text Entries
............................

Script text entries allow to put the executable script in the entry
itself instead of loading it from a file.  The first line of the entry,
everything after the prefix byte and up to the first newline ('0xa')
character, is the script name, and must not contain any kind of space
character, e.g., spaces or tabs.  The rest of the entry, up to the
trailing null byte, is the script to execute in the specified language.
The name needs to be unique among all script names, as GDB executes each
script only once based on its name.

   Here is an example from file 'py-section-script.c' in the GDB
testsuite.

     #include "symcat.h"
     #include "gdb/section-scripts.h"
     asm(
     ".pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n"
     ".byte " XSTRING (SECTION_SCRIPT_ID_PYTHON_TEXT) "\n"
     ".ascii \"gdb.inlined-script\\n\"\n"
     ".ascii \"class test_cmd (gdb.Command):\\n\"\n"
     ".ascii \"  def __init__ (self):\\n\"\n"
     ".ascii \"    super (test_cmd, self).__init__ ("
         "\\\"test-cmd\\\", gdb.COMMAND_OBSCURE)\\n\"\n"
     ".ascii \"  def invoke (self, arg, from_tty):\\n\"\n"
     ".ascii \"    print (\\\"test-cmd output, arg = %s\\\" % arg)\\n\"\n"
     ".ascii \"test_cmd ()\\n\"\n"
     ".byte 0\n"
     ".popsection\n"
     );

   Loading of inlined scripts requires a properly configured 'auto-load
safe-path' (*note Auto-loading safe path::).  The path to specify in
'auto-load safe-path' is the path of the file containing the
'.debug_gdb_scripts' section.


File: gdb.info,  Node: Which flavor to choose?,  Prev: dotdebug_gdb_scripts section,  Up: Auto-loading extensions

23.4.3 Which flavor to choose?
------------------------------

Given the multiple ways of auto-loading extensions, it might not always
be clear which one to choose.  This section provides some guidance.

Benefits of the '-gdb.EXT' way:

   * Can be used with file formats that don't support multiple sections.

   * Ease of finding scripts for public libraries.

     Scripts specified in the '.debug_gdb_scripts' section are searched
     for in the source search path.  For publicly installed libraries,
     e.g., 'libstdc++', there typically isn't a source directory in
     which to find the script.

   * Doesn't require source code additions.

Benefits of the '.debug_gdb_scripts' way:

   * Works with static linking.

     Scripts for libraries done the '-gdb.EXT' way require an objfile to
     trigger their loading.  When an application is statically linked
     the only objfile available is the executable, and it is cumbersome
     to attach all the scripts from all the input libraries to the
     executable's '-gdb.EXT' script.

   * Works with classes that are entirely inlined.

     Some classes can be entirely inlined, and thus there may not be an
     associated shared library to attach a '-gdb.EXT' script to.

   * Scripts needn't be copied out of the source tree.

     In some circumstances, apps can be built out of large collections
     of internal libraries, and the build infrastructure necessary to
     install the '-gdb.EXT' scripts in a place where GDB can find them
     is cumbersome.  It may be easier to specify the scripts in the
     '.debug_gdb_scripts' section as relative paths, and add a path to
     the top of the source tree to the source search path.


File: gdb.info,  Node: Multiple Extension Languages,  Next: Aliases,  Prev: Auto-loading extensions,  Up: Extending GDB

23.5 Multiple Extension Languages
=================================

The Guile and Python extension languages do not share any state, and
generally do not interfere with each other.  There are some things to be
aware of, however.

23.5.1 Python comes first
-------------------------

Python was GDB's first extension language, and to avoid breaking
existing behaviour Python comes first.  This is generally solved by the
"first one wins" principle.  GDB maintains a list of enabled extension
languages, and when it makes a call to an extension language, (say to
pretty-print a value), it tries each in turn until an extension language
indicates it has performed the request (e.g., has returned the
pretty-printed form of a value).  This extends to errors while
performing such requests: If an error happens while, for example, trying
to pretty-print an object then the error is reported and any following
extension languages are not tried.


File: gdb.info,  Node: Aliases,  Prev: Multiple Extension Languages,  Up: Extending GDB

23.6 Creating new spellings of existing commands
================================================

It is often useful to define alternate spellings of existing commands.
For example, if a new GDB command defined in Python has a long name to
type, it is handy to have an abbreviated version of it that involves
less typing.

   GDB itself uses aliases.  For example 's' is an alias of the 'step'
command even though it is otherwise an ambiguous abbreviation of other
commands like 'set' and 'show'.

   Aliases are also used to provide shortened or more common versions of
multi-word commands.  For example, GDB provides the 'tty' alias of the
'set inferior-tty' command.

   You can define a new alias with the 'alias' command.

'alias [-a] [--] ALIAS = COMMAND'

   ALIAS specifies the name of the new alias.  Each word of ALIAS must
consist of letters, numbers, dashes and underscores.

   COMMAND specifies the name of an existing command that is being
aliased.

   The '-a' option specifies that the new alias is an abbreviation of
the command.  Abbreviations are not shown in command lists displayed by
the 'help' command.

   The '--' option specifies the end of options, and is useful when
ALIAS begins with a dash.

   Here is a simple example showing how to make an abbreviation of a
command so that there is less to type.  Suppose you were tired of typing
'disas', the current shortest unambiguous abbreviation of the
'disassemble' command and you wanted an even shorter version named 'di'.
The following will accomplish this.

     (gdb) alias -a di = disas

   Note that aliases are different from user-defined commands.  With a
user-defined command, you also need to write documentation for it with
the 'document' command.  An alias automatically picks up the
documentation of the existing command.

   Here is an example where we make 'elms' an abbreviation of 'elements'
in the 'set print elements' command.  This is to show that you can make
an abbreviation of any part of a command.

     (gdb) alias -a set print elms = set print elements
     (gdb) alias -a show print elms = show print elements
     (gdb) set p elms 20
     (gdb) show p elms
     Limit on string chars or array elements to print is 200.

   Note that if you are defining an alias of a 'set' command, and you
want to have an alias for the corresponding 'show' command, then you
need to define the latter separately.

   Unambiguously abbreviated commands are allowed in COMMAND and ALIAS,
just as they are normally.

     (gdb) alias -a set pr elms = set p ele

   Finally, here is an example showing the creation of a one word alias
for a more complex command.  This creates alias 'spe' of the command
'set print elements'.

     (gdb) alias spe = set print elements
     (gdb) spe 20


File: gdb.info,  Node: Interpreters,  Next: TUI,  Prev: Extending GDB,  Up: Top

24 Command Interpreters
***********************

GDB supports multiple command interpreters, and some command
infrastructure to allow users or user interface writers to switch
between interpreters or run commands in other interpreters.

   GDB currently supports two command interpreters, the console
interpreter (sometimes called the command-line interpreter or CLI) and
the machine interface interpreter (or GDB/MI).  This manual describes
both of these interfaces in great detail.

   By default, GDB will start with the console interpreter.  However,
the user may choose to start GDB with another interpreter by specifying
the '-i' or '--interpreter' startup options.  Defined interpreters
include:

'console'
     The traditional console or command-line interpreter.  This is the
     most often used interpreter with GDB.  With no interpreter
     specified at runtime, GDB will use this interpreter.

'mi'
     The newest GDB/MI interface (currently 'mi2').  Used primarily by
     programs wishing to use GDB as a backend for a debugger GUI or an
     IDE. For more information, see *note The GDB/MI Interface: GDB/MI.

'mi2'
     The current GDB/MI interface.

'mi1'
     The GDB/MI interface included in GDB 5.1, 5.2, and 5.3.

   You may execute commands in any interpreter from the current
interpreter using the appropriate command.  If you are running the
console interpreter, simply use the 'interpreter-exec' command:

     interpreter-exec mi "-data-list-register-names"

   GDB/MI has a similar command, although it is only available in
versions of GDB which support GDB/MI version 2 (or greater).

   Note that 'interpreter-exec' only changes the interpreter for the
duration of the specified command.  It does not change the interpreter
permanently.

   Although you may only choose a single interpreter at startup, it is
possible to run an independent interpreter on a specified input/output
device (usually a tty).

   For example, consider a debugger GUI or IDE that wants to provide a
GDB console view.  It may do so by embedding a terminal emulator widget
in its GUI, starting GDB in the traditional command-line mode with
stdin/stdout/stderr redirected to that terminal, and then creating an MI
interpreter running on a specified input/output device.  The console
interpreter created by GDB at startup handles commands the user types in
the terminal widget, while the GUI controls and synchronizes state with
GDB using the separate MI interpreter.

   To start a new secondary "user interface" running MI, use the
'new-ui' command:

     new-ui INTERPRETER TTY

   The INTERPRETER parameter specifies the interpreter to run.  This
accepts the same values as the 'interpreter-exec' command.  For example,
'console', 'mi', 'mi2', etc.  The TTY parameter specifies the name of
the bidirectional file the interpreter uses for input/output, usually
the name of a pseudoterminal slave on Unix systems.  For example:

     (gdb) new-ui mi /dev/pts/9

runs an MI interpreter on '/dev/pts/9'.


File: gdb.info,  Node: TUI,  Next: Emacs,  Prev: Interpreters,  Up: Top

25 GDB Text User Interface
**************************

* Menu:

* TUI Overview::                TUI overview
* TUI Keys::                    TUI key bindings
* TUI Single Key Mode::         TUI single key mode
* TUI Commands::                TUI-specific commands
* TUI Configuration::           TUI configuration variables

The GDB Text User Interface (TUI) is a terminal interface which uses the
'curses' library to show the source file, the assembly output, the
program registers and GDB commands in separate text windows.  The TUI
mode is supported only on platforms where a suitable version of the
'curses' library is available.

   The TUI mode is enabled by default when you invoke GDB as 'gdb -tui'.
You can also switch in and out of TUI mode while GDB runs by using
various TUI commands and key bindings, such as 'tui enable' or 'C-x
C-a'.  *Note TUI Commands: TUI Commands, and *note TUI Key Bindings: TUI
Keys.


File: gdb.info,  Node: TUI Overview,  Next: TUI Keys,  Up: TUI

25.1 TUI Overview
=================

In TUI mode, GDB can display several text windows:

_command_
     This window is the GDB command window with the GDB prompt and the
     GDB output.  The GDB input is still managed using readline.

_source_
     The source window shows the source file of the program.  The
     current line and active breakpoints are displayed in this window.

_assembly_
     The assembly window shows the disassembly output of the program.

_register_
     This window shows the processor registers.  Registers are
     highlighted when their values change.

   The source and assembly windows show the current program position by
highlighting the current line and marking it with a '>' marker.
Breakpoints are indicated with two markers.  The first marker indicates
the breakpoint type:

'B'
     Breakpoint which was hit at least once.

'b'
     Breakpoint which was never hit.

'H'
     Hardware breakpoint which was hit at least once.

'h'
     Hardware breakpoint which was never hit.

   The second marker indicates whether the breakpoint is enabled or not:

'+'
     Breakpoint is enabled.

'-'
     Breakpoint is disabled.

   The source, assembly and register windows are updated when the
current thread changes, when the frame changes, or when the program
counter changes.

   These windows are not all visible at the same time.  The command
window is always visible.  The others can be arranged in several
layouts:

   * source only,

   * assembly only,

   * source and assembly,

   * source and registers, or

   * assembly and registers.

   A status line above the command window shows the following
information:

_target_
     Indicates the current GDB target.  (*note Specifying a Debugging
     Target: Targets.).

_process_
     Gives the current process or thread number.  When no process is
     being debugged, this field is set to 'No process'.

_function_
     Gives the current function name for the selected frame.  The name
     is demangled if demangling is turned on (*note Print Settings::).
     When there is no symbol corresponding to the current program
     counter, the string '??' is displayed.

_line_
     Indicates the current line number for the selected frame.  When the
     current line number is not known, the string '??' is displayed.

_pc_
     Indicates the current program counter address.


File: gdb.info,  Node: TUI Keys,  Next: TUI Single Key Mode,  Prev: TUI Overview,  Up: TUI

25.2 TUI Key Bindings
=====================

The TUI installs several key bindings in the readline keymaps (*note
Command Line Editing::).  The following key bindings are installed for
both TUI mode and the GDB standard mode.

'C-x C-a'
'C-x a'
'C-x A'
     Enter or leave the TUI mode.  When leaving the TUI mode, the curses
     window management stops and GDB operates using its standard mode,
     writing on the terminal directly.  When reentering the TUI mode,
     control is given back to the curses windows.  The screen is then
     refreshed.

'C-x 1'
     Use a TUI layout with only one window.  The layout will either be
     'source' or 'assembly'.  When the TUI mode is not active, it will
     switch to the TUI mode.

     Think of this key binding as the Emacs 'C-x 1' binding.

'C-x 2'
     Use a TUI layout with at least two windows.  When the current
     layout already has two windows, the next layout with two windows is
     used.  When a new layout is chosen, one window will always be
     common to the previous layout and the new one.

     Think of it as the Emacs 'C-x 2' binding.

'C-x o'
     Change the active window.  The TUI associates several key bindings
     (like scrolling and arrow keys) with the active window.  This
     command gives the focus to the next TUI window.

     Think of it as the Emacs 'C-x o' binding.

'C-x s'
     Switch in and out of the TUI SingleKey mode that binds single keys
     to GDB commands (*note TUI Single Key Mode::).

   The following key bindings only work in the TUI mode:

<PgUp>
     Scroll the active window one page up.

<PgDn>
     Scroll the active window one page down.

<Up>
     Scroll the active window one line up.

<Down>
     Scroll the active window one line down.

<Left>
     Scroll the active window one column left.

<Right>
     Scroll the active window one column right.

'C-L'
     Refresh the screen.

   Because the arrow keys scroll the active window in the TUI mode, they
are not available for their normal use by readline unless the command
window has the focus.  When another window is active, you must use other
readline key bindings such as 'C-p', 'C-n', 'C-b' and 'C-f' to control
the command window.


File: gdb.info,  Node: TUI Single Key Mode,  Next: TUI Commands,  Prev: TUI Keys,  Up: TUI

25.3 TUI Single Key Mode
========================

The TUI also provides a "SingleKey" mode, which binds several frequently
used GDB commands to single keys.  Type 'C-x s' to switch into this
mode, where the following key bindings are used:

'c'
     continue

'd'
     down

'f'
     finish

'n'
     next

'o'
     nexti.  The shortcut letter 'o' stands for "step Over".

'q'
     exit the SingleKey mode.

'r'
     run

's'
     step

'i'
     stepi.  The shortcut letter 'i' stands for "step Into".

'u'
     up

'v'
     info locals

'w'
     where

   Other keys temporarily switch to the GDB command prompt.  The key
that was pressed is inserted in the editing buffer so that it is
possible to type most GDB commands without interaction with the TUI
SingleKey mode.  Once the command is entered the TUI SingleKey mode is
restored.  The only way to permanently leave this mode is by typing 'q'
or 'C-x s'.


File: gdb.info,  Node: TUI Commands,  Next: TUI Configuration,  Prev: TUI Single Key Mode,  Up: TUI

25.4 TUI-specific Commands
==========================

The TUI has specific commands to control the text windows.  These
commands are always available, even when GDB is not in the TUI mode.
When GDB is in the standard mode, most of these commands will
automatically switch to the TUI mode.

   Note that if GDB's 'stdout' is not connected to a terminal, or GDB
has been started with the machine interface interpreter (*note The
GDB/MI Interface: GDB/MI.), most of these commands will fail with an
error, because it would not be possible or desirable to enable curses
window management.

'tui enable'
     Activate TUI mode.  The last active TUI window layout will be used
     if TUI mode has prevsiouly been used in the current debugging
     session, otherwise a default layout is used.

'tui disable'
     Disable TUI mode, returning to the console interpreter.

'info win'
     List and give the size of all displayed windows.

'layout NAME'
     Changes which TUI windows are displayed.  In each layout the
     command window is always displayed, the NAME parameter controls
     which additional windows are displayed, and can be any of the
     following:

     'next'
          Display the next layout.

     'prev'
          Display the previous layout.

     'src'
          Display the source and command windows.

     'asm'
          Display the assembly and command windows.

     'split'
          Display the source, assembly, and command windows.

     'regs'
          When in 'src' layout display the register, source, and command
          windows.  When in 'asm' or 'split' layout display the
          register, assembler, and command windows.

'focus NAME'
     Changes which TUI window is currently active for scrolling.  The
     NAME parameter can be any of the following:

     'next'
          Make the next window active for scrolling.

     'prev'
          Make the previous window active for scrolling.

     'src'
          Make the source window active for scrolling.

     'asm'
          Make the assembly window active for scrolling.

     'regs'
          Make the register window active for scrolling.

     'cmd'
          Make the command window active for scrolling.

'refresh'
     Refresh the screen.  This is similar to typing 'C-L'.

'tui reg GROUP'
     Changes the register group displayed in the tui register window to
     GROUP.  If the register window is not currently displayed this
     command will cause the register window to be displayed.  The list
     of register groups, as well as their order is target specific.  The
     following groups are available on most targets:
     'next'
          Repeatedly selecting this group will cause the display to
          cycle through all of the available register groups.

     'prev'
          Repeatedly selecting this group will cause the display to
          cycle through all of the available register groups in the
          reverse order to NEXT.

     'general'
          Display the general registers.
     'float'
          Display the floating point registers.
     'system'
          Display the system registers.
     'vector'
          Display the vector registers.
     'all'
          Display all registers.

'update'
     Update the source window and the current execution point.

'winheight NAME +COUNT'
'winheight NAME -COUNT'
     Change the height of the window NAME by COUNT lines.  Positive
     counts increase the height, while negative counts decrease it.  The
     NAME parameter can be one of 'src' (the source window), 'cmd' (the
     command window), 'asm' (the disassembly window), or 'regs' (the
     register display window).

'tabset NCHARS'
     Set the width of tab stops to be NCHARS characters.  This setting
     affects the display of TAB characters in the source and assembly
     windows.


File: gdb.info,  Node: TUI Configuration,  Prev: TUI Commands,  Up: TUI

25.5 TUI Configuration Variables
================================

Several configuration variables control the appearance of TUI windows.

'set tui border-kind KIND'
     Select the border appearance for the source, assembly and register
     windows.  The possible values are the following:
     'space'
          Use a space character to draw the border.

     'ascii'
          Use ASCII characters '+', '-' and '|' to draw the border.

     'acs'
          Use the Alternate Character Set to draw the border.  The
          border is drawn using character line graphics if the terminal
          supports them.

'set tui border-mode MODE'
'set tui active-border-mode MODE'
     Select the display attributes for the borders of the inactive
     windows or the active window.  The MODE can be one of the
     following:
     'normal'
          Use normal attributes to display the border.

     'standout'
          Use standout mode.

     'reverse'
          Use reverse video mode.

     'half'
          Use half bright mode.

     'half-standout'
          Use half bright and standout mode.

     'bold'
          Use extra bright or bold mode.

     'bold-standout'
          Use extra bright or bold and standout mode.


File: gdb.info,  Node: Emacs,  Next: GDB/MI,  Prev: TUI,  Up: Top

26 Using GDB under GNU Emacs
****************************

A special interface allows you to use GNU Emacs to view (and edit) the
source files for the program you are debugging with GDB.

   To use this interface, use the command 'M-x gdb' in Emacs.  Give the
executable file you want to debug as an argument.  This command starts
GDB as a subprocess of Emacs, with input and output through a newly
created Emacs buffer.

   Running GDB under Emacs can be just like running GDB normally except
for two things:

   * All "terminal" input and output goes through an Emacs buffer,
     called the GUD buffer.

     This applies both to GDB commands and their output, and to the
     input and output done by the program you are debugging.

     This is useful because it means that you can copy the text of
     previous commands and input them again; you can even use parts of
     the output in this way.

     All the facilities of Emacs' Shell mode are available for
     interacting with your program.  In particular, you can send signals
     the usual way--for example, 'C-c C-c' for an interrupt, 'C-c C-z'
     for a stop.

   * GDB displays source code through Emacs.

     Each time GDB displays a stack frame, Emacs automatically finds the
     source file for that frame and puts an arrow ('=>') at the left
     margin of the current line.  Emacs uses a separate buffer for
     source display, and splits the screen to show both your GDB session
     and the source.

     Explicit GDB 'list' or search commands still produce output as
     usual, but you probably have no reason to use them from Emacs.

   We call this "text command mode".  Emacs 22.1, and later, also uses a
graphical mode, enabled by default, which provides further buffers that
can control the execution and describe the state of your program.  *Note
(Emacs)GDB Graphical Interface::.

   If you specify an absolute file name when prompted for the 'M-x gdb'
argument, then Emacs sets your current working directory to where your
program resides.  If you only specify the file name, then Emacs sets
your current working directory to the directory associated with the
previous buffer.  In this case, GDB may find your program by searching
your environment's 'PATH' variable, but on some operating systems it
might not find the source.  So, although the GDB input and output
session proceeds normally, the auxiliary buffer does not display the
current source and line of execution.

   The initial working directory of GDB is printed on the top line of
the GUD buffer and this serves as a default for the commands that
specify files for GDB to operate on.  *Note Commands to Specify Files:
Files.

   By default, 'M-x gdb' calls the program called 'gdb'.  If you need to
call GDB by a different name (for example, if you keep several
configurations around, with different names) you can customize the Emacs
variable 'gud-gdb-command-name' to run the one you want.

   In the GUD buffer, you can use these special Emacs commands in
addition to the standard Shell mode commands:

'C-h m'
     Describe the features of Emacs' GUD Mode.

'C-c C-s'
     Execute to another source line, like the GDB 'step' command; also
     update the display window to show the current file and location.

'C-c C-n'
     Execute to next source line in this function, skipping all function
     calls, like the GDB 'next' command.  Then update the display window
     to show the current file and location.

'C-c C-i'
     Execute one instruction, like the GDB 'stepi' command; update
     display window accordingly.

'C-c C-f'
     Execute until exit from the selected stack frame, like the GDB
     'finish' command.

'C-c C-r'
     Continue execution of your program, like the GDB 'continue'
     command.

'C-c <'
     Go up the number of frames indicated by the numeric argument (*note
     Numeric Arguments: (Emacs)Arguments.), like the GDB 'up' command.

'C-c >'
     Go down the number of frames indicated by the numeric argument,
     like the GDB 'down' command.

   In any source file, the Emacs command 'C-x <SPC>' ('gud-break') tells
GDB to set a breakpoint on the source line point is on.

   In text command mode, if you type 'M-x speedbar', Emacs displays a
separate frame which shows a backtrace when the GUD buffer is current.
Move point to any frame in the stack and type <RET> to make it become
the current frame and display the associated source in the source
buffer.  Alternatively, click 'Mouse-2' to make the selected frame
become the current one.  In graphical mode, the speedbar displays watch
expressions.

   If you accidentally delete the source-display buffer, an easy way to
get it back is to type the command 'f' in the GDB buffer, to request a
frame display; when you run under Emacs, this recreates the source
buffer if necessary to show you the context of the current frame.

   The source files displayed in Emacs are in ordinary Emacs buffers
which are visiting the source files in the usual way.  You can edit the
files with these buffers if you wish; but keep in mind that GDB
communicates with Emacs in terms of line numbers.  If you add or delete
lines from the text, the line numbers that GDB knows cease to correspond
properly with the code.

   A more detailed description of Emacs' interaction with GDB is given
in the Emacs manual (*note (Emacs)Debuggers::).


File: gdb.info,  Node: GDB/MI,  Next: Annotations,  Prev: Emacs,  Up: Top

27 The GDB/MI Interface
***********************

* Menu:

* GDB/MI General Design::
* GDB/MI Command Syntax::
* GDB/MI Compatibility with CLI::
* GDB/MI Development and Front Ends::
* GDB/MI Output Records::
* GDB/MI Simple Examples::
* GDB/MI Command Description Format::
* GDB/MI Breakpoint Commands::
* GDB/MI Catchpoint Commands::
* GDB/MI Program Context::
* GDB/MI Thread Commands::
* GDB/MI Ada Tasking Commands::
* GDB/MI Program Execution::
* GDB/MI Stack Manipulation::
* GDB/MI Variable Objects::
* GDB/MI Data Manipulation::
* GDB/MI Tracepoint Commands::
* GDB/MI Symbol Query::
* GDB/MI File Commands::
* GDB/MI Target Manipulation::
* GDB/MI File Transfer Commands::
* GDB/MI Ada Exceptions Commands::
* GDB/MI Support Commands::
* GDB/MI Miscellaneous Commands::

Function and Purpose
====================

GDB/MI is a line based machine oriented text interface to GDB and is
activated by specifying using the '--interpreter' command line option
(*note Mode Options::).  It is specifically intended to support the
development of systems which use the debugger as just one small
component of a larger system.

   This chapter is a specification of the GDB/MI interface.  It is
written in the form of a reference manual.

   Note that GDB/MI is still under construction, so some of the features
described below are incomplete and subject to change (*note GDB/MI
Development and Front Ends: GDB/MI Development and Front Ends.).

Notation and Terminology
========================

This chapter uses the following notation:

   * '|' separates two alternatives.

   * '[ SOMETHING ]' indicates that SOMETHING is optional: it may or may
     not be given.

   * '( GROUP )*' means that GROUP inside the parentheses may repeat
     zero or more times.

   * '( GROUP )+' means that GROUP inside the parentheses may repeat one
     or more times.

   * '"STRING"' means a literal STRING.

* Menu:

* GDB/MI General Design::
* GDB/MI Command Syntax::
* GDB/MI Compatibility with CLI::
* GDB/MI Development and Front Ends::
* GDB/MI Output Records::
* GDB/MI Simple Examples::
* GDB/MI Command Description Format::
* GDB/MI Breakpoint Commands::
* GDB/MI Catchpoint Commands::
* GDB/MI Program Context::
* GDB/MI Thread Commands::
* GDB/MI Ada Tasking Commands::
* GDB/MI Program Execution::
* GDB/MI Stack Manipulation::
* GDB/MI Variable Objects::
* GDB/MI Data Manipulation::
* GDB/MI Tracepoint Commands::
* GDB/MI Symbol Query::
* GDB/MI File Commands::
* GDB/MI Target Manipulation::
* GDB/MI File Transfer Commands::
* GDB/MI Ada Exceptions Commands::
* GDB/MI Support Commands::
* GDB/MI Miscellaneous Commands::


File: gdb.info,  Node: GDB/MI General Design,  Next: GDB/MI Command Syntax,  Up: GDB/MI

27.1 GDB/MI General Design
==========================

Interaction of a GDB/MI frontend with GDB involves three parts--commands
sent to GDB, responses to those commands and notifications.  Each
command results in exactly one response, indicating either successful
completion of the command, or an error.  For the commands that do not
resume the target, the response contains the requested information.  For
the commands that resume the target, the response only indicates whether
the target was successfully resumed.  Notifications is the mechanism for
reporting changes in the state of the target, or in GDB state, that
cannot conveniently be associated with a command and reported as part of
that command response.

   The important examples of notifications are:

   * Exec notifications.  These are used to report changes in target
     state--when a target is resumed, or stopped.  It would not be
     feasible to include this information in response of resuming
     commands, because one resume commands can result in multiple events
     in different threads.  Also, quite some time may pass before any
     event happens in the target, while a frontend needs to know whether
     the resuming command itself was successfully executed.

   * Console output, and status notifications.  Console output
     notifications are used to report output of CLI commands, as well as
     diagnostics for other commands.  Status notifications are used to
     report the progress of a long-running operation.  Naturally,
     including this information in command response would mean no output
     is produced until the command is finished, which is undesirable.

   * General notifications.  Commands may have various side effects on
     the GDB or target state beyond their official purpose.  For
     example, a command may change the selected thread.  Although such
     changes can be included in command response, using notification
     allows for more orthogonal frontend design.

   There's no guarantee that whenever an MI command reports an error,
GDB or the target are in any specific state, and especially, the state
is not reverted to the state before the MI command was processed.
Therefore, whenever an MI command results in an error, we recommend that
the frontend refreshes all the information shown in the user interface.

* Menu:

* Context management::
* Asynchronous and non-stop modes::
* Thread groups::


File: gdb.info,  Node: Context management,  Next: Asynchronous and non-stop modes,  Up: GDB/MI General Design

27.1.1 Context management
-------------------------

27.1.1.1 Threads and Frames
...........................

In most cases when GDB accesses the target, this access is done in
context of a specific thread and frame (*note Frames::).  Often, even
when accessing global data, the target requires that a thread be
specified.  The CLI interface maintains the selected thread and frame,
and supplies them to target on each command.  This is convenient,
because a command line user would not want to specify that information
explicitly on each command, and because user interacts with GDB via a
single terminal, so no confusion is possible as to what thread and frame
are the current ones.

   In the case of MI, the concept of selected thread and frame is less
useful.  First, a frontend can easily remember this information itself.
Second, a graphical frontend can have more than one window, each one
used for debugging a different thread, and the frontend might want to
access additional threads for internal purposes.  This increases the
risk that by relying on implicitly selected thread, the frontend may be
operating on a wrong one.  Therefore, each MI command should explicitly
specify which thread and frame to operate on.  To make it possible, each
MI command accepts the '--thread' and '--frame' options, the value to
each is GDB global identifier for thread and frame to operate on.

   Usually, each top-level window in a frontend allows the user to
select a thread and a frame, and remembers the user selection for
further operations.  However, in some cases GDB may suggest that the
current thread or frame be changed.  For example, when stopping on a
breakpoint it is reasonable to switch to the thread where breakpoint is
hit.  For another example, if the user issues the CLI 'thread' or
'frame' commands via the frontend, it is desirable to change the
frontend's selection to the one specified by user.  GDB communicates the
suggestion to change current thread and frame using the
'=thread-selected' notification.

   Note that historically, MI shares the selected thread with CLI, so
frontends used the '-thread-select' to execute commands in the right
context.  However, getting this to work right is cumbersome.  The
simplest way is for frontend to emit '-thread-select' command before
every command.  This doubles the number of commands that need to be
sent.  The alternative approach is to suppress '-thread-select' if the
selected thread in GDB is supposed to be identical to the thread the
frontend wants to operate on.  However, getting this optimization right
can be tricky.  In particular, if the frontend sends several commands to
GDB, and one of the commands changes the selected thread, then the
behaviour of subsequent commands will change.  So, a frontend should
either wait for response from such problematic commands, or explicitly
add '-thread-select' for all subsequent commands.  No frontend is known
to do this exactly right, so it is suggested to just always pass the
'--thread' and '--frame' options.

27.1.1.2 Language
.................

The execution of several commands depends on which language is selected.
By default, the current language (*note show language::) is used.  But
for commands known to be language-sensitive, it is recommended to use
the '--language' option.  This option takes one argument, which is the
name of the language to use while executing the command.  For instance:

     -data-evaluate-expression --language c "sizeof (void*)"
     ^done,value="4"
     (gdb)

   The valid language names are the same names accepted by the 'set
language' command (*note Manually::), excluding 'auto', 'local' or
'unknown'.


File: gdb.info,  Node: Asynchronous and non-stop modes,  Next: Thread groups,  Prev: Context management,  Up: GDB/MI General Design

27.1.2 Asynchronous command execution and non-stop mode
-------------------------------------------------------

On some targets, GDB is capable of processing MI commands even while the
target is running.  This is called "asynchronous command execution"
(*note Background Execution::).  The frontend may specify a preferrence
for asynchronous execution using the '-gdb-set mi-async 1' command,
which should be emitted before either running the executable or
attaching to the target.  After the frontend has started the executable
or attached to the target, it can find if asynchronous execution is
enabled using the '-list-target-features' command.

'-gdb-set mi-async on'
'-gdb-set mi-async off'
     Set whether MI is in asynchronous mode.

     When 'off', which is the default, MI execution commands (e.g.,
     '-exec-continue') are foreground commands, and GDB waits for the
     program to stop before processing further commands.

     When 'on', MI execution commands are background execution commands
     (e.g., '-exec-continue' becomes the equivalent of the 'c&' CLI
     command), and so GDB is capable of processing MI commands even
     while the target is running.

'-gdb-show mi-async'
     Show whether MI asynchronous mode is enabled.

   Note: In GDB version 7.7 and earlier, this option was called
'target-async' instead of 'mi-async', and it had the effect of both
putting MI in asynchronous mode and making CLI background commands
possible.  CLI background commands are now always possible "out of the
box" if the target supports them.  The old spelling is kept as a
deprecated alias for backwards compatibility.

   Even if GDB can accept a command while target is running, many
commands that access the target do not work when the target is running.
Therefore, asynchronous command execution is most useful when combined
with non-stop mode (*note Non-Stop Mode::).  Then, it is possible to
examine the state of one thread, while other threads are running.

   When a given thread is running, MI commands that try to access the
target in the context of that thread may not work, or may work only on
some targets.  In particular, commands that try to operate on thread's
stack will not work, on any target.  Commands that read memory, or
modify breakpoints, may work or not work, depending on the target.  Note
that even commands that operate on global state, such as 'print', 'set',
and breakpoint commands, still access the target in the context of a
specific thread, so frontend should try to find a stopped thread and
perform the operation on that thread (using the '--thread' option).

   Which commands will work in the context of a running thread is highly
target dependent.  However, the two commands '-exec-interrupt', to stop
a thread, and '-thread-info', to find the state of a thread, will always
work.


File: gdb.info,  Node: Thread groups,  Prev: Asynchronous and non-stop modes,  Up: GDB/MI General Design

27.1.3 Thread groups
--------------------

GDB may be used to debug several processes at the same time.  On some
platfroms, GDB may support debugging of several hardware systems, each
one having several cores with several different processes running on
each core.  This section describes the MI mechanism to support such
debugging scenarios.

   The key observation is that regardless of the structure of the
target, MI can have a global list of threads, because most commands that
accept the '--thread' option do not need to know what process that
thread belongs to.  Therefore, it is not necessary to introduce neither
additional '--process' option, nor an notion of the current process in
the MI interface.  The only strictly new feature that is required is the
ability to find how the threads are grouped into processes.

   To allow the user to discover such grouping, and to support arbitrary
hierarchy of machines/cores/processes, MI introduces the concept of a
"thread group".  Thread group is a collection of threads and other
thread groups.  A thread group always has a string identifier, a type,
and may have additional attributes specific to the type.  A new command,
'-list-thread-groups', returns the list of top-level thread groups,
which correspond to processes that GDB is debugging at the moment.  By
passing an identifier of a thread group to the '-list-thread-groups'
command, it is possible to obtain the members of specific thread group.

   To allow the user to easily discover processes, and other objects, he
wishes to debug, a concept of "available thread group" is introduced.
Available thread group is an thread group that GDB is not debugging, but
that can be attached to, using the '-target-attach' command.  The list
of available top-level thread groups can be obtained using
'-list-thread-groups --available'.  In general, the content of a thread
group may be only retrieved only after attaching to that thread group.

   Thread groups are related to inferiors (*note Inferiors and
Programs::).  Each inferior corresponds to a thread group of a special
type 'process', and some additional operations are permitted on such
thread groups.


File: gdb.info,  Node: GDB/MI Command Syntax,  Next: GDB/MI Compatibility with CLI,  Prev: GDB/MI General Design,  Up: GDB/MI

27.2 GDB/MI Command Syntax
==========================

* Menu:

* GDB/MI Input Syntax::
* GDB/MI Output Syntax::


File: gdb.info,  Node: GDB/MI Input Syntax,  Next: GDB/MI Output Syntax,  Up: GDB/MI Command Syntax

27.2.1 GDB/MI Input Syntax
--------------------------

'COMMAND ==>'
     'CLI-COMMAND | MI-COMMAND'

'CLI-COMMAND ==>'
     '[ TOKEN ] CLI-COMMAND NL', where CLI-COMMAND is any existing GDB
     CLI command.

'MI-COMMAND ==>'
     '[ TOKEN ] "-" OPERATION ( " " OPTION )* [ " --" ] ( " " PARAMETER
     )* NL'

'TOKEN ==>'
     "any sequence of digits"

'OPTION ==>'
     '"-" PARAMETER [ " " PARAMETER ]'

'PARAMETER ==>'
     'NON-BLANK-SEQUENCE | C-STRING'

'OPERATION ==>'
     _any of the operations described in this chapter_

'NON-BLANK-SEQUENCE ==>'
     _anything, provided it doesn't contain special characters such as
     "-", NL, """ and of course " "_

'C-STRING ==>'
     '""" SEVEN-BIT-ISO-C-STRING-CONTENT """'

'NL ==>'
     'CR | CR-LF'

Notes:

   * The CLI commands are still handled by the MI interpreter; their
     output is described below.

   * The 'TOKEN', when present, is passed back when the command
     finishes.

   * Some MI commands accept optional arguments as part of the parameter
     list.  Each option is identified by a leading '-' (dash) and may be
     followed by an optional argument parameter.  Options occur first in
     the parameter list and can be delimited from normal parameters
     using '--' (this is useful when some parameters begin with a dash).

   Pragmatics:

   * We want easy access to the existing CLI syntax (for debugging).

   * We want it to be easy to spot a MI operation.


File: gdb.info,  Node: GDB/MI Output Syntax,  Prev: GDB/MI Input Syntax,  Up: GDB/MI Command Syntax

27.2.2 GDB/MI Output Syntax
---------------------------

The output from GDB/MI consists of zero or more out-of-band records
followed, optionally, by a single result record.  This result record is
for the most recent command.  The sequence of output records is
terminated by '(gdb)'.

   If an input command was prefixed with a 'TOKEN' then the
corresponding output for that command will also be prefixed by that same
TOKEN.

'OUTPUT ==>'
     '( OUT-OF-BAND-RECORD )* [ RESULT-RECORD ] "(gdb)" NL'

'RESULT-RECORD ==>'
     ' [ TOKEN ] "^" RESULT-CLASS ( "," RESULT )* NL'

'OUT-OF-BAND-RECORD ==>'
     'ASYNC-RECORD | STREAM-RECORD'

'ASYNC-RECORD ==>'
     'EXEC-ASYNC-OUTPUT | STATUS-ASYNC-OUTPUT | NOTIFY-ASYNC-OUTPUT'

'EXEC-ASYNC-OUTPUT ==>'
     '[ TOKEN ] "*" ASYNC-OUTPUT NL'

'STATUS-ASYNC-OUTPUT ==>'
     '[ TOKEN ] "+" ASYNC-OUTPUT NL'

'NOTIFY-ASYNC-OUTPUT ==>'
     '[ TOKEN ] "=" ASYNC-OUTPUT NL'

'ASYNC-OUTPUT ==>'
     'ASYNC-CLASS ( "," RESULT )*'

'RESULT-CLASS ==>'
     '"done" | "running" | "connected" | "error" | "exit"'

'ASYNC-CLASS ==>'
     '"stopped" | OTHERS' (where OTHERS will be added depending on the
     needs--this is still in development).

'RESULT ==>'
     ' VARIABLE "=" VALUE'

'VARIABLE ==>'
     ' STRING '

'VALUE ==>'
     ' CONST | TUPLE | LIST '

'CONST ==>'
     'C-STRING'

'TUPLE ==>'
     ' "{}" | "{" RESULT ( "," RESULT )* "}" '

'LIST ==>'
     ' "[]" | "[" VALUE ( "," VALUE )* "]" | "[" RESULT ( "," RESULT )*
     "]" '

'STREAM-RECORD ==>'
     'CONSOLE-STREAM-OUTPUT | TARGET-STREAM-OUTPUT | LOG-STREAM-OUTPUT'

'CONSOLE-STREAM-OUTPUT ==>'
     '"~" C-STRING NL'

'TARGET-STREAM-OUTPUT ==>'
     '"@" C-STRING NL'

'LOG-STREAM-OUTPUT ==>'
     '"&" C-STRING NL'

'NL ==>'
     'CR | CR-LF'

'TOKEN ==>'
     _any sequence of digits_.

Notes:

   * All output sequences end in a single line containing a period.

   * The 'TOKEN' is from the corresponding request.  Note that for all
     async output, while the token is allowed by the grammar and may be
     output by future versions of GDB for select async output messages,
     it is generally omitted.  Frontends should treat all async output
     as reporting general changes in the state of the target and there
     should be no need to associate async output to any prior command.

   * STATUS-ASYNC-OUTPUT contains on-going status information about the
     progress of a slow operation.  It can be discarded.  All status
     output is prefixed by '+'.

   * EXEC-ASYNC-OUTPUT contains asynchronous state change on the target
     (stopped, started, disappeared).  All async output is prefixed by
     '*'.

   * NOTIFY-ASYNC-OUTPUT contains supplementary information that the
     client should handle (e.g., a new breakpoint information).  All
     notify output is prefixed by '='.

   * CONSOLE-STREAM-OUTPUT is output that should be displayed as is in
     the console.  It is the textual response to a CLI command.  All the
     console output is prefixed by '~'.

   * TARGET-STREAM-OUTPUT is the output produced by the target program.
     All the target output is prefixed by '@'.

   * LOG-STREAM-OUTPUT is output text coming from GDB's internals, for
     instance messages that should be displayed as part of an error log.
     All the log output is prefixed by '&'.

   * New GDB/MI commands should only output LISTS containing VALUES.

   *Note GDB/MI Stream Records: GDB/MI Stream Records, for more details
about the various output records.


File: gdb.info,  Node: GDB/MI Compatibility with CLI,  Next: GDB/MI Development and Front Ends,  Prev: GDB/MI Command Syntax,  Up: GDB/MI

27.3 GDB/MI Compatibility with CLI
==================================

For the developers convenience CLI commands can be entered directly, but
there may be some unexpected behaviour.  For example, commands that
query the user will behave as if the user replied yes, breakpoint
command lists are not executed and some CLI commands, such as 'if',
'when' and 'define', prompt for further input with '>', which is not
valid MI output.

   This feature may be removed at some stage in the future and it is
recommended that front ends use the '-interpreter-exec' command (*note
-interpreter-exec::).


File: gdb.info,  Node: GDB/MI Development and Front Ends,  Next: GDB/MI Output Records,  Prev: GDB/MI Compatibility with CLI,  Up: GDB/MI

27.4 GDB/MI Development and Front Ends
======================================

The application which takes the MI output and presents the state of the
program being debugged to the user is called a "front end".

   Although GDB/MI is still incomplete, it is currently being used by a
variety of front ends to GDB.  This makes it difficult to introduce new
functionality without breaking existing usage.  This section tries to
minimize the problems by describing how the protocol might change.

   Some changes in MI need not break a carefully designed front end, and
for these the MI version will remain unchanged.  The following is a list
of changes that may occur within one level, so front ends should parse
MI output in a way that can handle them:

   * New MI commands may be added.

   * New fields may be added to the output of any MI command.

   * The range of values for fields with specified values, e.g.,
     'in_scope' (*note -var-update::) may be extended.

   If the changes are likely to break front ends, the MI version level
will be increased by one.  This will allow the front end to parse the
output according to the MI version.  Apart from mi0, new versions of GDB
will not support old versions of MI and it will be the responsibility of
the front end to work with the new one.

   The best way to avoid unexpected changes in MI that might break your
front end is to make your project known to GDB developers and follow
development on <gdb@sourceware.org> and <gdb-patches@sourceware.org>.


File: gdb.info,  Node: GDB/MI Output Records,  Next: GDB/MI Simple Examples,  Prev: GDB/MI Development and Front Ends,  Up: GDB/MI

27.5 GDB/MI Output Records
==========================

* Menu:

* GDB/MI Result Records::
* GDB/MI Stream Records::
* GDB/MI Async Records::
* GDB/MI Breakpoint Information::
* GDB/MI Frame Information::
* GDB/MI Thread Information::
* GDB/MI Ada Exception Information::


File: gdb.info,  Node: GDB/MI Result Records,  Next: GDB/MI Stream Records,  Up: GDB/MI Output Records

27.5.1 GDB/MI Result Records
----------------------------

In addition to a number of out-of-band notifications, the response to a
GDB/MI command includes one of the following result indications:

'"^done" [ "," RESULTS ]'
     The synchronous operation was successful, 'RESULTS' are the return
     values.

'"^running"'
     This result record is equivalent to '^done'.  Historically, it was
     output instead of '^done' if the command has resumed the target.
     This behaviour is maintained for backward compatibility, but all
     frontends should treat '^done' and '^running' identically and rely
     on the '*running' output record to determine which threads are
     resumed.

'"^connected"'
     GDB has connected to a remote target.

'"^error" "," "msg=" C-STRING [ "," "code=" C-STRING ]'
     The operation failed.  The 'msg=C-STRING' variable contains the
     corresponding error message.

     If present, the 'code=C-STRING' variable provides an error code on
     which consumers can rely on to detect the corresponding error
     condition.  At present, only one error code is defined:

     '"undefined-command"'
          Indicates that the command causing the error does not exist.

'"^exit"'
     GDB has terminated.


File: gdb.info,  Node: GDB/MI Stream Records,  Next: GDB/MI Async Records,  Prev: GDB/MI Result Records,  Up: GDB/MI Output Records

27.5.2 GDB/MI Stream Records
----------------------------

GDB internally maintains a number of output streams: the console, the
target, and the log.  The output intended for each of these streams is
funneled through the GDB/MI interface using "stream records".

   Each stream record begins with a unique "prefix character" which
identifies its stream (*note GDB/MI Output Syntax: GDB/MI Output
Syntax.).  In addition to the prefix, each stream record contains a
'STRING-OUTPUT'.  This is either raw text (with an implicit new line) or
a quoted C string (which does not contain an implicit newline).

'"~" STRING-OUTPUT'
     The console output stream contains text that should be displayed in
     the CLI console window.  It contains the textual responses to CLI
     commands.

'"@" STRING-OUTPUT'
     The target output stream contains any textual output from the
     running target.  This is only present when GDB's event loop is
     truly asynchronous, which is currently only the case for remote
     targets.

'"&" STRING-OUTPUT'
     The log stream contains debugging messages being produced by GDB's
     internals.


File: gdb.info,  Node: GDB/MI Async Records,  Next: GDB/MI Breakpoint Information,  Prev: GDB/MI Stream Records,  Up: GDB/MI Output Records

27.5.3 GDB/MI Async Records
---------------------------

"Async" records are used to notify the GDB/MI client of additional
changes that have occurred.  Those changes can either be a consequence
of GDB/MI commands (e.g., a breakpoint modified) or a result of target
activity (e.g., target stopped).

   The following is the list of possible async records:

'*running,thread-id="THREAD"'
     The target is now running.  The THREAD field can be the global
     thread ID of the the thread that is now running, and it can be
     'all' if all threads are running.  The frontend should assume that
     no interaction with a running thread is possible after this
     notification is produced.  The frontend should not assume that this
     notification is output only once for any command.  GDB may emit
     this notification several times, either for different threads,
     because it cannot resume all threads together, or even for a single
     thread, if the thread must be stepped though some code before
     letting it run freely.

'*stopped,reason="REASON",thread-id="ID",stopped-threads="STOPPED",core="CORE"'
     The target has stopped.  The REASON field can have one of the
     following values:

     'breakpoint-hit'
          A breakpoint was reached.
     'watchpoint-trigger'
          A watchpoint was triggered.
     'read-watchpoint-trigger'
          A read watchpoint was triggered.
     'access-watchpoint-trigger'
          An access watchpoint was triggered.
     'function-finished'
          An -exec-finish or similar CLI command was accomplished.
     'location-reached'
          An -exec-until or similar CLI command was accomplished.
     'watchpoint-scope'
          A watchpoint has gone out of scope.
     'end-stepping-range'
          An -exec-next, -exec-next-instruction, -exec-step,
          -exec-step-instruction or similar CLI command was
          accomplished.
     'exited-signalled'
          The inferior exited because of a signal.
     'exited'
          The inferior exited.
     'exited-normally'
          The inferior exited normally.
     'signal-received'
          A signal was received by the inferior.
     'solib-event'
          The inferior has stopped due to a library being loaded or
          unloaded.  This can happen when 'stop-on-solib-events' (*note
          Files::) is set or when a 'catch load' or 'catch unload'
          catchpoint is in use (*note Set Catchpoints::).
     'fork'
          The inferior has forked.  This is reported when 'catch fork'
          (*note Set Catchpoints::) has been used.
     'vfork'
          The inferior has vforked.  This is reported in when 'catch
          vfork' (*note Set Catchpoints::) has been used.
     'syscall-entry'
          The inferior entered a system call.  This is reported when
          'catch syscall' (*note Set Catchpoints::) has been used.
     'syscall-return'
          The inferior returned from a system call.  This is reported
          when 'catch syscall' (*note Set Catchpoints::) has been used.
     'exec'
          The inferior called 'exec'.  This is reported when 'catch
          exec' (*note Set Catchpoints::) has been used.

     The ID field identifies the global thread ID of the thread that
     directly caused the stop - for example by hitting a breakpoint.
     Depending on whether all-stop mode is in effect (*note All-Stop
     Mode::), GDB may either stop all threads, or only the thread that
     directly triggered the stop.  If all threads are stopped, the
     STOPPED field will have the value of '"all"'.  Otherwise, the value
     of the STOPPED field will be a list of thread identifiers.
     Presently, this list will always include a single thread, but
     frontend should be prepared to see several threads in the list.
     The CORE field reports the processor core on which the stop event
     has happened.  This field may be absent if such information is not
     available.

'=thread-group-added,id="ID"'
'=thread-group-removed,id="ID"'
     A thread group was either added or removed.  The ID field contains
     the GDB identifier of the thread group.  When a thread group is
     added, it generally might not be associated with a running process.
     When a thread group is removed, its id becomes invalid and cannot
     be used in any way.

'=thread-group-started,id="ID",pid="PID"'
     A thread group became associated with a running program, either
     because the program was just started or the thread group was
     attached to a program.  The ID field contains the GDB identifier of
     the thread group.  The PID field contains process identifier,
     specific to the operating system.

'=thread-group-exited,id="ID"[,exit-code="CODE"]'
     A thread group is no longer associated with a running program,
     either because the program has exited, or because it was detached
     from.  The ID field contains the GDB identifier of the thread
     group.  The CODE field is the exit code of the inferior; it exists
     only when the inferior exited with some code.

'=thread-created,id="ID",group-id="GID"'
'=thread-exited,id="ID",group-id="GID"'
     A thread either was created, or has exited.  The ID field contains
     the global GDB identifier of the thread.  The GID field identifies
     the thread group this thread belongs to.

'=thread-selected,id="ID"[,frame="FRAME"]'
     Informs that the selected thread or frame were changed.  This
     notification is not emitted as result of the '-thread-select' or
     '-stack-select-frame' commands, but is emitted whenever an MI
     command that is not documented to change the selected thread and
     frame actually changes them.  In particular, invoking, directly or
     indirectly (via user-defined command), the CLI 'thread' or 'frame'
     commands, will generate this notification.  Changing the thread or
     frame from another user interface (see *note Interpreters::) will
     also generate this notification.

     The FRAME field is only present if the newly selected thread is
     stopped.  See *note GDB/MI Frame Information:: for the format of
     its value.

     We suggest that in response to this notification, front ends
     highlight the selected thread and cause subsequent commands to
     apply to that thread.

'=library-loaded,...'
     Reports that a new library file was loaded by the program.  This
     notification has 5 fields--ID, TARGET-NAME, HOST-NAME,
     SYMBOLS-LOADED and RANGES.  The ID field is an opaque identifier of
     the library.  For remote debugging case, TARGET-NAME and HOST-NAME
     fields give the name of the library file on the target, and on the
     host respectively.  For native debugging, both those fields have
     the same value.  The SYMBOLS-LOADED field is emitted only for
     backward compatibility and should not be relied on to convey any
     useful information.  The THREAD-GROUP field, if present, specifies
     the id of the thread group in whose context the library was loaded.
     If the field is absent, it means the library was loaded in the
     context of all present thread groups.  The RANGES field specifies
     the ranges of addresses belonging to this library.

'=library-unloaded,...'
     Reports that a library was unloaded by the program.  This
     notification has 3 fields--ID, TARGET-NAME and HOST-NAME with the
     same meaning as for the '=library-loaded' notification.  The
     THREAD-GROUP field, if present, specifies the id of the thread
     group in whose context the library was unloaded.  If the field is
     absent, it means the library was unloaded in the context of all
     present thread groups.

'=traceframe-changed,num=TFNUM,tracepoint=TPNUM'
'=traceframe-changed,end'
     Reports that the trace frame was changed and its new number is
     TFNUM.  The number of the tracepoint associated with this trace
     frame is TPNUM.

'=tsv-created,name=NAME,initial=INITIAL'
     Reports that the new trace state variable NAME is created with
     initial value INITIAL.

'=tsv-deleted,name=NAME'
'=tsv-deleted'
     Reports that the trace state variable NAME is deleted or all trace
     state variables are deleted.

'=tsv-modified,name=NAME,initial=INITIAL[,current=CURRENT]'
     Reports that the trace state variable NAME is modified with the
     initial value INITIAL.  The current value CURRENT of trace state
     variable is optional and is reported if the current value of trace
     state variable is known.

'=breakpoint-created,bkpt={...}'
'=breakpoint-modified,bkpt={...}'
'=breakpoint-deleted,id=NUMBER'
     Reports that a breakpoint was created, modified, or deleted,
     respectively.  Only user-visible breakpoints are reported to the MI
     user.

     The BKPT argument is of the same form as returned by the various
     breakpoint commands; *Note GDB/MI Breakpoint Commands::.  The
     NUMBER is the ordinal number of the breakpoint.

     Note that if a breakpoint is emitted in the result record of a
     command, then it will not also be emitted in an async record.

'=record-started,thread-group="ID",method="METHOD"[,format="FORMAT"]'
'=record-stopped,thread-group="ID"'
     Execution log recording was either started or stopped on an
     inferior.  The ID is the GDB identifier of the thread group
     corresponding to the affected inferior.

     The METHOD field indicates the method used to record execution.  If
     the method in use supports multiple recording formats, FORMAT will
     be present and contain the currently used format.  *Note Process
     Record and Replay::, for existing method and format values.

'=cmd-param-changed,param=PARAM,value=VALUE'
     Reports that a parameter of the command 'set PARAM' is changed to
     VALUE.  In the multi-word 'set' command, the PARAM is the whole
     parameter list to 'set' command.  For example, In command 'set
     check type on', PARAM is 'check type' and VALUE is 'on'.

'=memory-changed,thread-group=ID,addr=ADDR,len=LEN[,type="code"]'
     Reports that bytes from ADDR to DATA + LEN were written in an
     inferior.  The ID is the identifier of the thread group
     corresponding to the affected inferior.  The optional 'type="code"'
     part is reported if the memory written to holds executable code.


File: gdb.info,  Node: GDB/MI Breakpoint Information,  Next: GDB/MI Frame Information,  Prev: GDB/MI Async Records,  Up: GDB/MI Output Records

27.5.4 GDB/MI Breakpoint Information
------------------------------------

When GDB reports information about a breakpoint, a tracepoint, a
watchpoint, or a catchpoint, it uses a tuple with the following fields:

'number'
     The breakpoint number.  For a breakpoint that represents one
     location of a multi-location breakpoint, this will be a dotted
     pair, like '1.2'.

'type'
     The type of the breakpoint.  For ordinary breakpoints this will be
     'breakpoint', but many values are possible.

'catch-type'
     If the type of the breakpoint is 'catchpoint', then this indicates
     the exact type of catchpoint.

'disp'
     This is the breakpoint disposition--either 'del', meaning that the
     breakpoint will be deleted at the next stop, or 'keep', meaning
     that the breakpoint will not be deleted.

'enabled'
     This indicates whether the breakpoint is enabled, in which case the
     value is 'y', or disabled, in which case the value is 'n'.  Note
     that this is not the same as the field 'enable'.

'addr'
     The address of the breakpoint.  This may be a hexidecimal number,
     giving the address; or the string '<PENDING>', for a pending
     breakpoint; or the string '<MULTIPLE>', for a breakpoint with
     multiple locations.  This field will not be present if no address
     can be determined.  For example, a watchpoint does not have an
     address.

'func'
     If known, the function in which the breakpoint appears.  If not
     known, this field is not present.

'filename'
     The name of the source file which contains this function, if known.
     If not known, this field is not present.

'fullname'
     The full file name of the source file which contains this function,
     if known.  If not known, this field is not present.

'line'
     The line number at which this breakpoint appears, if known.  If not
     known, this field is not present.

'at'
     If the source file is not known, this field may be provided.  If
     provided, this holds the address of the breakpoint, possibly
     followed by a symbol name.

'pending'
     If this breakpoint is pending, this field is present and holds the
     text used to set the breakpoint, as entered by the user.

'evaluated-by'
     Where this breakpoint's condition is evaluated, either 'host' or
     'target'.

'thread'
     If this is a thread-specific breakpoint, then this identifies the
     thread in which the breakpoint can trigger.

'task'
     If this breakpoint is restricted to a particular Ada task, then
     this field will hold the task identifier.

'cond'
     If the breakpoint is conditional, this is the condition expression.

'ignore'
     The ignore count of the breakpoint.

'enable'
     The enable count of the breakpoint.

'traceframe-usage'
     FIXME.

'static-tracepoint-marker-string-id'
     For a static tracepoint, the name of the static tracepoint marker.

'mask'
     For a masked watchpoint, this is the mask.

'pass'
     A tracepoint's pass count.

'original-location'
     The location of the breakpoint as originally specified by the user.
     This field is optional.

'times'
     The number of times the breakpoint has been hit.

'installed'
     This field is only given for tracepoints.  This is either 'y',
     meaning that the tracepoint is installed, or 'n', meaning that it
     is not.

'what'
     Some extra data, the exact contents of which are type-dependent.

   For example, here is what the output of '-break-insert' (*note GDB/MI
Breakpoint Commands::) might be:

     -> -break-insert main
     <- ^done,bkpt={number="1",type="breakpoint",disp="keep",
         enabled="y",addr="0x08048564",func="main",file="myprog.c",
         fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"],
         times="0"}
     <- (gdb)


File: gdb.info,  Node: GDB/MI Frame Information,  Next: GDB/MI Thread Information,  Prev: GDB/MI Breakpoint Information,  Up: GDB/MI Output Records

27.5.5 GDB/MI Frame Information
-------------------------------

Response from many MI commands includes an information about stack
frame.  This information is a tuple that may have the following fields:

'level'
     The level of the stack frame.  The innermost frame has the level of
     zero.  This field is always present.

'func'
     The name of the function corresponding to the frame.  This field
     may be absent if GDB is unable to determine the function name.

'addr'
     The code address for the frame.  This field is always present.

'file'
     The name of the source files that correspond to the frame's code
     address.  This field may be absent.

'line'
     The source line corresponding to the frames' code address.  This
     field may be absent.

'from'
     The name of the binary file (either executable or shared library)
     the corresponds to the frame's code address.  This field may be
     absent.


File: gdb.info,  Node: GDB/MI Thread Information,  Next: GDB/MI Ada Exception Information,  Prev: GDB/MI Frame Information,  Up: GDB/MI Output Records

27.5.6 GDB/MI Thread Information
--------------------------------

Whenever GDB has to report an information about a thread, it uses a
tuple with the following fields.  The fields are always present unless
stated otherwise.

'id'
     The global numeric id assigned to the thread by GDB.

'target-id'
     The target-specific string identifying the thread.

'details'
     Additional information about the thread provided by the target.  It
     is supposed to be human-readable and not interpreted by the
     frontend.  This field is optional.

'name'
     The name of the thread.  If the user specified a name using the
     'thread name' command, then this name is given.  Otherwise, if GDB
     can extract the thread name from the target, then that name is
     given.  If GDB cannot find the thread name, then this field is
     omitted.

'state'
     The execution state of the thread, either 'stopped' or 'running',
     depending on whether the thread is presently running.

'frame'
     The stack frame currently executing in the thread.  This field is
     only present if the thread is stopped.  Its format is documented in
     *note GDB/MI Frame Information::.

'core'
     The value of this field is an integer number of the processor core
     the thread was last seen on.  This field is optional.


File: gdb.info,  Node: GDB/MI Ada Exception Information,  Prev: GDB/MI Thread Information,  Up: GDB/MI Output Records

27.5.7 GDB/MI Ada Exception Information
---------------------------------------

Whenever a '*stopped' record is emitted because the program stopped
after hitting an exception catchpoint (*note Set Catchpoints::), GDB
provides the name of the exception that was raised via the
'exception-name' field.  Also, for exceptions that were raised with an
exception message, GDB provides that message via the 'exception-message'
field.


File: gdb.info,  Node: GDB/MI Simple Examples,  Next: GDB/MI Command Description Format,  Prev: GDB/MI Output Records,  Up: GDB/MI

27.6 Simple Examples of GDB/MI Interaction
==========================================

This subsection presents several simple examples of interaction using
the GDB/MI interface.  In these examples, '->' means that the following
line is passed to GDB/MI as input, while '<-' means the output received
from GDB/MI.

   Note the line breaks shown in the examples are here only for
readability, they don't appear in the real output.

Setting a Breakpoint
--------------------

Setting a breakpoint generates synchronous output which contains
detailed information of the breakpoint.

     -> -break-insert main
     <- ^done,bkpt={number="1",type="breakpoint",disp="keep",
         enabled="y",addr="0x08048564",func="main",file="myprog.c",
         fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"],
         times="0"}
     <- (gdb)

Program Execution
-----------------

Program execution generates asynchronous records and MI gives the reason
that execution stopped.

     -> -exec-run
     <- ^running
     <- (gdb)
     <- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
        frame={addr="0x08048564",func="main",
        args=[{name="argc",value="1"},{name="argv",value="0xbfc4d4d4"}],
        file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"}
     <- (gdb)
     -> -exec-continue
     <- ^running
     <- (gdb)
     <- *stopped,reason="exited-normally"
     <- (gdb)

Quitting GDB
------------

Quitting GDB just prints the result class '^exit'.

     -> (gdb)
     <- -gdb-exit
     <- ^exit

   Please note that '^exit' is printed immediately, but it might take
some time for GDB to actually exit.  During that time, GDB performs
necessary cleanups, including killing programs being debugged or
disconnecting from debug hardware, so the frontend should wait till GDB
exits and should only forcibly kill GDB if it fails to exit in
reasonable time.

A Bad Command
-------------

Here's what happens if you pass a non-existent command:

     -> -rubbish
     <- ^error,msg="Undefined MI command: rubbish"
     <- (gdb)


File: gdb.info,  Node: GDB/MI Command Description Format,  Next: GDB/MI Breakpoint Commands,  Prev: GDB/MI Simple Examples,  Up: GDB/MI

27.7 GDB/MI Command Description Format
======================================

The remaining sections describe blocks of commands.  Each block of
commands is laid out in a fashion similar to this section.

Motivation
----------

The motivation for this collection of commands.

Introduction
------------

A brief introduction to this collection of commands as a whole.

Commands
--------

For each command in the block, the following is described:

Synopsis
........

      -command ARGS...

Result
......

GDB Command
...........

The corresponding GDB CLI command(s), if any.

Example
.......

Example(s) formatted for readability.  Some of the described commands
have not been implemented yet and these are labeled N.A. (not
available).


File: gdb.info,  Node: GDB/MI Breakpoint Commands,  Next: GDB/MI Catchpoint Commands,  Prev: GDB/MI Command Description Format,  Up: GDB/MI

27.8 GDB/MI Breakpoint Commands
===============================

This section documents GDB/MI commands for manipulating breakpoints.

The '-break-after' Command
--------------------------

Synopsis
........

      -break-after NUMBER COUNT

   The breakpoint number NUMBER is not in effect until it has been hit
COUNT times.  To see how this is reflected in the output of the
'-break-list' command, see the description of the '-break-list' command
below.

GDB Command
...........

The corresponding GDB command is 'ignore'.

Example
.......

     (gdb)
     -break-insert main
     ^done,bkpt={number="1",type="breakpoint",disp="keep",
     enabled="y",addr="0x000100d0",func="main",file="hello.c",
     fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
     times="0"}
     (gdb)
     -break-after 1 3
     ~
     ^done
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="1",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
     line="5",thread-groups=["i1"],times="0",ignore="3"}]}
     (gdb)

The '-break-commands' Command
-----------------------------

Synopsis
........

      -break-commands NUMBER [ COMMAND1 ... COMMANDN ]

   Specifies the CLI commands that should be executed when breakpoint
NUMBER is hit.  The parameters COMMAND1 to COMMANDN are the commands.
If no command is specified, any previously-set commands are cleared.
*Note Break Commands::.  Typical use of this functionality is tracing a
program, that is, printing of values of some variables whenever
breakpoint is hit and then continuing.

GDB Command
...........

The corresponding GDB command is 'commands'.

Example
.......

     (gdb)
     -break-insert main
     ^done,bkpt={number="1",type="breakpoint",disp="keep",
     enabled="y",addr="0x000100d0",func="main",file="hello.c",
     fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
     times="0"}
     (gdb)
     -break-commands 1 "print v" "continue"
     ^done
     (gdb)

The '-break-condition' Command
------------------------------

Synopsis
........

      -break-condition NUMBER EXPR

   Breakpoint NUMBER will stop the program only if the condition in EXPR
is true.  The condition becomes part of the '-break-list' output (see
the description of the '-break-list' command below).

GDB Command
...........

The corresponding GDB command is 'condition'.

Example
.......

     (gdb)
     -break-condition 1 1
     ^done
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="1",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
     line="5",cond="1",thread-groups=["i1"],times="0",ignore="3"}]}
     (gdb)

The '-break-delete' Command
---------------------------

Synopsis
........

      -break-delete ( BREAKPOINT )+

   Delete the breakpoint(s) whose number(s) are specified in the
argument list.  This is obviously reflected in the breakpoint list.

GDB Command
...........

The corresponding GDB command is 'delete'.

Example
.......

     (gdb)
     -break-delete 1
     ^done
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="0",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[]}
     (gdb)

The '-break-disable' Command
----------------------------

Synopsis
........

      -break-disable ( BREAKPOINT )+

   Disable the named BREAKPOINT(s).  The field 'enabled' in the break
list is now set to 'n' for the named BREAKPOINT(s).

GDB Command
...........

The corresponding GDB command is 'disable'.

Example
.......

     (gdb)
     -break-disable 2
     ^done
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="1",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="n",
     addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
     line="5",thread-groups=["i1"],times="0"}]}
     (gdb)

The '-break-enable' Command
---------------------------

Synopsis
........

      -break-enable ( BREAKPOINT )+

   Enable (previously disabled) BREAKPOINT(s).

GDB Command
...........

The corresponding GDB command is 'enable'.

Example
.......

     (gdb)
     -break-enable 2
     ^done
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="1",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
     addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
     line="5",thread-groups=["i1"],times="0"}]}
     (gdb)

The '-break-info' Command
-------------------------

Synopsis
........

      -break-info BREAKPOINT

   Get information about a single breakpoint.

   The result is a table of breakpoints.  *Note GDB/MI Breakpoint
Information::, for details on the format of each breakpoint in the
table.

GDB Command
...........

The corresponding GDB command is 'info break BREAKPOINT'.

Example
.......

N.A.

The '-break-insert' Command
---------------------------

Synopsis
........

      -break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ]
         [ -c CONDITION ] [ -i IGNORE-COUNT ]
         [ -p THREAD-ID ] [ LOCATION ]

If specified, LOCATION, can be one of:

LINESPEC LOCATION
     A linespec location.  *Note Linespec Locations::.

EXPLICIT LOCATION
     An explicit location.  GDB/MI explicit locations are analogous to
     the CLI's explicit locations using the option names listed below.
     *Note Explicit Locations::.

     '--source FILENAME'
          The source file name of the location.  This option requires
          the use of either '--function' or '--line'.

     '--function FUNCTION'
          The name of a function or method.

     '--label LABEL'
          The name of a label.

     '--line LINEOFFSET'
          An absolute or relative line offset from the start of the
          location.

ADDRESS LOCATION
     An address location, *ADDRESS.  *Note Address Locations::.

The possible optional parameters of this command are:

'-t'
     Insert a temporary breakpoint.
'-h'
     Insert a hardware breakpoint.
'-f'
     If LOCATION cannot be parsed (for example if it refers to unknown
     files or functions), create a pending breakpoint.  Without this
     flag, GDB will report an error, and won't create a breakpoint, if
     LOCATION cannot be parsed.
'-d'
     Create a disabled breakpoint.
'-a'
     Create a tracepoint.  *Note Tracepoints::.  When this parameter is
     used together with '-h', a fast tracepoint is created.
'-c CONDITION'
     Make the breakpoint conditional on CONDITION.
'-i IGNORE-COUNT'
     Initialize the IGNORE-COUNT.
'-p THREAD-ID'
     Restrict the breakpoint to the thread with the specified global
     THREAD-ID.

Result
......

*Note GDB/MI Breakpoint Information::, for details on the format of the
resulting breakpoint.

   Note: this format is open to change.

GDB Command
...........

The corresponding GDB commands are 'break', 'tbreak', 'hbreak', and
'thbreak'.

Example
.......

     (gdb)
     -break-insert main
     ^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",
     fullname="/home/foo/recursive2.c,line="4",thread-groups=["i1"],
     times="0"}
     (gdb)
     -break-insert -t foo
     ^done,bkpt={number="2",addr="0x00010774",file="recursive2.c",
     fullname="/home/foo/recursive2.c,line="11",thread-groups=["i1"],
     times="0"}
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="2",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x0001072c", func="main",file="recursive2.c",
     fullname="/home/foo/recursive2.c,"line="4",thread-groups=["i1"],
     times="0"},
     bkpt={number="2",type="breakpoint",disp="del",enabled="y",
     addr="0x00010774",func="foo",file="recursive2.c",
     fullname="/home/foo/recursive2.c",line="11",thread-groups=["i1"],
     times="0"}]}
     (gdb)

The '-dprintf-insert' Command
-----------------------------

Synopsis
........

      -dprintf-insert [ -t ] [ -f ] [ -d ]
         [ -c CONDITION ] [ -i IGNORE-COUNT ]
         [ -p THREAD-ID ] [ LOCATION ] [ FORMAT ]
         [ ARGUMENT ]

If supplied, LOCATION may be specified the same way as for the
'-break-insert' command.  *Note -break-insert::.

   The possible optional parameters of this command are:

'-t'
     Insert a temporary breakpoint.
'-f'
     If LOCATION cannot be parsed (for example, if it refers to unknown
     files or functions), create a pending breakpoint.  Without this
     flag, GDB will report an error, and won't create a breakpoint, if
     LOCATION cannot be parsed.
'-d'
     Create a disabled breakpoint.
'-c CONDITION'
     Make the breakpoint conditional on CONDITION.
'-i IGNORE-COUNT'
     Set the ignore count of the breakpoint (*note ignore count:
     Conditions.) to IGNORE-COUNT.
'-p THREAD-ID'
     Restrict the breakpoint to the thread with the specified global
     THREAD-ID.

Result
......

*Note GDB/MI Breakpoint Information::, for details on the format of the
resulting breakpoint.

GDB Command
...........

The corresponding GDB command is 'dprintf'.

Example
.......

     (gdb)
     4-dprintf-insert foo "At foo entry\n"
     4^done,bkpt={number="1",type="dprintf",disp="keep",enabled="y",
     addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
     fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
     times="0",script={"printf \"At foo entry\\n\"","continue"},
     original-location="foo"}
     (gdb)
     5-dprintf-insert 26 "arg=%d, g=%d\n" arg g
     5^done,bkpt={number="2",type="dprintf",disp="keep",enabled="y",
     addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
     fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
     times="0",script={"printf \"arg=%d, g=%d\\n\", arg, g","continue"},
     original-location="mi-dprintf.c:26"}
     (gdb)

The '-break-list' Command
-------------------------

Synopsis
........

      -break-list

   Displays the list of inserted breakpoints, showing the following
fields:

'Number'
     number of the breakpoint
'Type'
     type of the breakpoint: 'breakpoint' or 'watchpoint'
'Disposition'
     should the breakpoint be deleted or disabled when it is hit: 'keep'
     or 'nokeep'
'Enabled'
     is the breakpoint enabled or no: 'y' or 'n'
'Address'
     memory location at which the breakpoint is set
'What'
     logical location of the breakpoint, expressed by function name,
     file name, line number
'Thread-groups'
     list of thread groups to which this breakpoint applies
'Times'
     number of times the breakpoint has been hit

   If there are no breakpoints or watchpoints, the 'BreakpointTable'
'body' field is an empty list.

GDB Command
...........

The corresponding GDB command is 'info break'.

Example
.......

     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="2",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x000100d0",func="main",file="hello.c",line="5",thread-groups=["i1"],
     times="0"},
     bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
     addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c",
     line="13",thread-groups=["i1"],times="0"}]}
     (gdb)

   Here's an example of the result when there are no breakpoints:

     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="0",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[]}
     (gdb)

The '-break-passcount' Command
------------------------------

Synopsis
........

      -break-passcount TRACEPOINT-NUMBER PASSCOUNT

   Set the passcount for tracepoint TRACEPOINT-NUMBER to PASSCOUNT.  If
the breakpoint referred to by TRACEPOINT-NUMBER is not a tracepoint,
error is emitted.  This corresponds to CLI command 'passcount'.

The '-break-watch' Command
--------------------------

Synopsis
........

      -break-watch [ -a | -r ]

   Create a watchpoint.  With the '-a' option it will create an "access"
watchpoint, i.e., a watchpoint that triggers either on a read from or on
a write to the memory location.  With the '-r' option, the watchpoint
created is a "read" watchpoint, i.e., it will trigger only when the
memory location is accessed for reading.  Without either of the options,
the watchpoint created is a regular watchpoint, i.e., it will trigger
when the memory location is accessed for writing.  *Note Setting
Watchpoints: Set Watchpoints.

   Note that '-break-list' will report a single list of watchpoints and
breakpoints inserted.

GDB Command
...........

The corresponding GDB commands are 'watch', 'awatch', and 'rwatch'.

Example
.......

Setting a watchpoint on a variable in the 'main' function:

     (gdb)
     -break-watch x
     ^done,wpt={number="2",exp="x"}
     (gdb)
     -exec-continue
     ^running
     (gdb)
     *stopped,reason="watchpoint-trigger",wpt={number="2",exp="x"},
     value={old="-268439212",new="55"},
     frame={func="main",args=[],file="recursive2.c",
     fullname="/home/foo/bar/recursive2.c",line="5"}
     (gdb)

   Setting a watchpoint on a variable local to a function.  GDB will
stop the program execution twice: first for the variable changing value,
then for the watchpoint going out of scope.

     (gdb)
     -break-watch C
     ^done,wpt={number="5",exp="C"}
     (gdb)
     -exec-continue
     ^running
     (gdb)
     *stopped,reason="watchpoint-trigger",
     wpt={number="5",exp="C"},value={old="-276895068",new="3"},
     frame={func="callee4",args=[],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
     (gdb)
     -exec-continue
     ^running
     (gdb)
     *stopped,reason="watchpoint-scope",wpnum="5",
     frame={func="callee3",args=[{name="strarg",
     value="0x11940 \"A string argument.\""}],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
     (gdb)

   Listing breakpoints and watchpoints, at different points in the
program execution.  Note that once the watchpoint goes out of scope, it
is deleted.

     (gdb)
     -break-watch C
     ^done,wpt={number="2",exp="C"}
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="2",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x00010734",func="callee4",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",thread-groups=["i1"],
     times="1"},
     bkpt={number="2",type="watchpoint",disp="keep",
     enabled="y",addr="",what="C",thread-groups=["i1"],times="0"}]}
     (gdb)
     -exec-continue
     ^running
     (gdb)
     *stopped,reason="watchpoint-trigger",wpt={number="2",exp="C"},
     value={old="-276895068",new="3"},
     frame={func="callee4",args=[],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="2",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x00010734",func="callee4",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",thread-groups=["i1"],
     times="1"},
     bkpt={number="2",type="watchpoint",disp="keep",
     enabled="y",addr="",what="C",thread-groups=["i1"],times="-5"}]}
     (gdb)
     -exec-continue
     ^running
     ^done,reason="watchpoint-scope",wpnum="2",
     frame={func="callee3",args=[{name="strarg",
     value="0x11940 \"A string argument.\""}],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
     (gdb)
     -break-list
     ^done,BreakpointTable={nr_rows="1",nr_cols="6",
     hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
     {width="14",alignment="-1",col_name="type",colhdr="Type"},
     {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
     {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
     {width="10",alignment="-1",col_name="addr",colhdr="Address"},
     {width="40",alignment="2",col_name="what",colhdr="What"}],
     body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x00010734",func="callee4",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
     thread-groups=["i1"],times="1"}]}
     (gdb)


File: gdb.info,  Node: GDB/MI Catchpoint Commands,  Next: GDB/MI Program Context,  Prev: GDB/MI Breakpoint Commands,  Up: GDB/MI

27.9 GDB/MI Catchpoint Commands
===============================

This section documents GDB/MI commands for manipulating catchpoints.

* Menu:

* Shared Library GDB/MI Catchpoint Commands::
* Ada Exception GDB/MI Catchpoint Commands::


File: gdb.info,  Node: Shared Library GDB/MI Catchpoint Commands,  Next: Ada Exception GDB/MI Catchpoint Commands,  Up: GDB/MI Catchpoint Commands

27.9.1 Shared Library GDB/MI Catchpoints
----------------------------------------

The '-catch-load' Command
-------------------------

Synopsis
........

      -catch-load [ -t ] [ -d ] REGEXP

   Add a catchpoint for library load events.  If the '-t' option is
used, the catchpoint is a temporary one (*note Setting Breakpoints: Set
Breaks.).  If the '-d' option is used, the catchpoint is created in a
disabled state.  The 'regexp' argument is a regular expression used to
match the name of the loaded library.

GDB Command
...........

The corresponding GDB command is 'catch load'.

Example
.......

     -catch-load -t foo.so
     ^done,bkpt={number="1",type="catchpoint",disp="del",enabled="y",
     what="load of library matching foo.so",catch-type="load",times="0"}
     (gdb)

The '-catch-unload' Command
---------------------------

Synopsis
........

      -catch-unload [ -t ] [ -d ] REGEXP

   Add a catchpoint for library unload events.  If the '-t' option is
used, the catchpoint is a temporary one (*note Setting Breakpoints: Set
Breaks.).  If the '-d' option is used, the catchpoint is created in a
disabled state.  The 'regexp' argument is a regular expression used to
match the name of the unloaded library.

GDB Command
...........

The corresponding GDB command is 'catch unload'.

Example
.......

     -catch-unload -d bar.so
     ^done,bkpt={number="2",type="catchpoint",disp="keep",enabled="n",
     what="load of library matching bar.so",catch-type="unload",times="0"}
     (gdb)


File: gdb.info,  Node: Ada Exception GDB/MI Catchpoint Commands,  Prev: Shared Library GDB/MI Catchpoint Commands,  Up: GDB/MI Catchpoint Commands

27.9.2 Ada Exception GDB/MI Catchpoints
---------------------------------------

The following GDB/MI commands can be used to create catchpoints that
stop the execution when Ada exceptions are being raised.

The '-catch-assert' Command
---------------------------

Synopsis
........

      -catch-assert [ -c CONDITION] [ -d ] [ -t ]

   Add a catchpoint for failed Ada assertions.

   The possible optional parameters for this command are:

'-c CONDITION'
     Make the catchpoint conditional on CONDITION.
'-d'
     Create a disabled catchpoint.
'-t'
     Create a temporary catchpoint.

GDB Command
...........

The corresponding GDB command is 'catch assert'.

Example
.......

     -catch-assert
     ^done,bkptno="5",bkpt={number="5",type="breakpoint",disp="keep",
     enabled="y",addr="0x0000000000404888",what="failed Ada assertions",
     thread-groups=["i1"],times="0",
     original-location="__gnat_debug_raise_assert_failure"}
     (gdb)

The '-catch-exception' Command
------------------------------

Synopsis
........

      -catch-exception [ -c CONDITION] [ -d ] [ -e EXCEPTION-NAME ]
         [ -t ] [ -u ]

   Add a catchpoint stopping when Ada exceptions are raised.  By
default, the command stops the program when any Ada exception gets
raised.  But it is also possible, by using some of the optional
parameters described below, to create more selective catchpoints.

   The possible optional parameters for this command are:

'-c CONDITION'
     Make the catchpoint conditional on CONDITION.
'-d'
     Create a disabled catchpoint.
'-e EXCEPTION-NAME'
     Only stop when EXCEPTION-NAME is raised.  This option cannot be
     used combined with '-u'.
'-t'
     Create a temporary catchpoint.
'-u'
     Stop only when an unhandled exception gets raised.  This option
     cannot be used combined with '-e'.

GDB Command
...........

The corresponding GDB commands are 'catch exception' and 'catch
exception unhandled'.

Example
.......

     -catch-exception -e Program_Error
     ^done,bkptno="4",bkpt={number="4",type="breakpoint",disp="keep",
     enabled="y",addr="0x0000000000404874",
     what="`Program_Error' Ada exception", thread-groups=["i1"],
     times="0",original-location="__gnat_debug_raise_exception"}
     (gdb)

The '-catch-handlers' Command
-----------------------------

Synopsis
........

      -catch-handlers [ -c CONDITION] [ -d ] [ -e EXCEPTION-NAME ]
         [ -t ]

   Add a catchpoint stopping when Ada exceptions are handled.  By
default, the command stops the program when any Ada exception gets
handled.  But it is also possible, by using some of the optional
parameters described below, to create more selective catchpoints.

   The possible optional parameters for this command are:

'-c CONDITION'
     Make the catchpoint conditional on CONDITION.
'-d'
     Create a disabled catchpoint.
'-e EXCEPTION-NAME'
     Only stop when EXCEPTION-NAME is handled.
'-t'
     Create a temporary catchpoint.

GDB Command
...........

The corresponding GDB command is 'catch handlers'.

Example
.......

     -catch-handlers -e Constraint_Error
     ^done,bkptno="4",bkpt={number="4",type="breakpoint",disp="keep",
     enabled="y",addr="0x0000000000402f68",
     what="`Constraint_Error' Ada exception handlers",thread-groups=["i1"],
     times="0",original-location="__gnat_begin_handler"}
     (gdb)


File: gdb.info,  Node: GDB/MI Program Context,  Next: GDB/MI Thread Commands,  Prev: GDB/MI Catchpoint Commands,  Up: GDB/MI

27.10 GDB/MI Program Context
============================

The '-exec-arguments' Command
-----------------------------

Synopsis
........

      -exec-arguments ARGS

   Set the inferior program arguments, to be used in the next
'-exec-run'.

GDB Command
...........

The corresponding GDB command is 'set args'.

Example
.......

     (gdb)
     -exec-arguments -v word
     ^done
     (gdb)

The '-environment-cd' Command
-----------------------------

Synopsis
........

      -environment-cd PATHDIR

   Set GDB's working directory.

GDB Command
...........

The corresponding GDB command is 'cd'.

Example
.......

     (gdb)
     -environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
     ^done
     (gdb)

The '-environment-directory' Command
------------------------------------

Synopsis
........

      -environment-directory [ -r ] [ PATHDIR ]+

   Add directories PATHDIR to beginning of search path for source files.
If the '-r' option is used, the search path is reset to the default
search path.  If directories PATHDIR are supplied in addition to the
'-r' option, the search path is first reset and then addition occurs as
normal.  Multiple directories may be specified, separated by blanks.
Specifying multiple directories in a single command results in the
directories added to the beginning of the search path in the same order
they were presented in the command.  If blanks are needed as part of a
directory name, double-quotes should be used around the name.  In the
command output, the path will show up separated by the system
directory-separator character.  The directory-separator character must
not be used in any directory name.  If no directories are specified, the
current search path is displayed.

GDB Command
...........

The corresponding GDB command is 'dir'.

Example
.......

     (gdb)
     -environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
     ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
     (gdb)
     -environment-directory ""
     ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
     (gdb)
     -environment-directory -r /home/jjohnstn/src/gdb /usr/src
     ^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
     (gdb)
     -environment-directory -r
     ^done,source-path="$cdir:$cwd"
     (gdb)

The '-environment-path' Command
-------------------------------

Synopsis
........

      -environment-path [ -r ] [ PATHDIR ]+

   Add directories PATHDIR to beginning of search path for object files.
If the '-r' option is used, the search path is reset to the original
search path that existed at gdb start-up.  If directories PATHDIR are
supplied in addition to the '-r' option, the search path is first reset
and then addition occurs as normal.  Multiple directories may be
specified, separated by blanks.  Specifying multiple directories in a
single command results in the directories added to the beginning of the
search path in the same order they were presented in the command.  If
blanks are needed as part of a directory name, double-quotes should be
used around the name.  In the command output, the path will show up
separated by the system directory-separator character.  The
directory-separator character must not be used in any directory name.
If no directories are specified, the current path is displayed.

GDB Command
...........

The corresponding GDB command is 'path'.

Example
.......

     (gdb)
     -environment-path
     ^done,path="/usr/bin"
     (gdb)
     -environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
     ^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
     (gdb)
     -environment-path -r /usr/local/bin
     ^done,path="/usr/local/bin:/usr/bin"
     (gdb)

The '-environment-pwd' Command
------------------------------

Synopsis
........

      -environment-pwd

   Show the current working directory.

GDB Command
...........

The corresponding GDB command is 'pwd'.

Example
.......

     (gdb)
     -environment-pwd
     ^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
     (gdb)


File: gdb.info,  Node: GDB/MI Thread Commands,  Next: GDB/MI Ada Tasking Commands,  Prev: GDB/MI Program Context,  Up: GDB/MI

27.11 GDB/MI Thread Commands
============================

The '-thread-info' Command
--------------------------

Synopsis
........

      -thread-info [ THREAD-ID ]

   Reports information about either a specific thread, if the THREAD-ID
parameter is present, or about all threads.  THREAD-ID is the thread's
global thread ID. When printing information about all threads, also
reports the global ID of the current thread.

GDB Command
...........

The 'info thread' command prints the same information about all threads.

Result
......

The result contains the following attributes:

'threads'
     A list of threads.  The format of the elements of the list is
     described in *note GDB/MI Thread Information::.

'current-thread-id'
     The global id of the currently selected thread.  This field is
     omitted if there is no selected thread (for example, when the
     selected inferior is not running, and therefore has no threads) or
     if a THREAD-ID argument was passed to the command.

Example
.......

     -thread-info
     ^done,threads=[
     {id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
        frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",
                args=[]},state="running"},
     {id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
        frame={level="0",addr="0x0804891f",func="foo",
                args=[{name="i",value="10"}],
                file="/tmp/a.c",fullname="/tmp/a.c",line="158"},
                state="running"}],
     current-thread-id="1"
     (gdb)

The '-thread-list-ids' Command
------------------------------

Synopsis
........

      -thread-list-ids

   Produces a list of the currently known global GDB thread ids.  At the
end of the list it also prints the total number of such threads.

   This command is retained for historical reasons, the '-thread-info'
command should be used instead.

GDB Command
...........

Part of 'info threads' supplies the same information.

Example
.......

     (gdb)
     -thread-list-ids
     ^done,thread-ids={thread-id="3",thread-id="2",thread-id="1"},
     current-thread-id="1",number-of-threads="3"
     (gdb)

The '-thread-select' Command
----------------------------

Synopsis
........

      -thread-select THREAD-ID

   Make thread with global thread number THREAD-ID the current thread.
It prints the number of the new current thread, and the topmost frame
for that thread.

   This command is deprecated in favor of explicitly using the
'--thread' option to each command.

GDB Command
...........

The corresponding GDB command is 'thread'.

Example
.......

     (gdb)
     -exec-next
     ^running
     (gdb)
     *stopped,reason="end-stepping-range",thread-id="2",line="187",
     file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
     (gdb)
     -thread-list-ids
     ^done,
     thread-ids={thread-id="3",thread-id="2",thread-id="1"},
     number-of-threads="3"
     (gdb)
     -thread-select 3
     ^done,new-thread-id="3",
     frame={level="0",func="vprintf",
     args=[{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""},
     {name="arg",value="0x2"}],file="vprintf.c",line="31"}
     (gdb)


File: gdb.info,  Node: GDB/MI Ada Tasking Commands,  Next: GDB/MI Program Execution,  Prev: GDB/MI Thread Commands,  Up: GDB/MI

27.12 GDB/MI Ada Tasking Commands
=================================

The '-ada-task-info' Command
----------------------------

Synopsis
........

      -ada-task-info [ TASK-ID ]

   Reports information about either a specific Ada task, if the TASK-ID
parameter is present, or about all Ada tasks.

GDB Command
...........

The 'info tasks' command prints the same information about all Ada tasks
(*note Ada Tasks::).

Result
......

The result is a table of Ada tasks.  The following columns are defined
for each Ada task:

'current'
     This field exists only for the current thread.  It has the value
     '*'.

'id'
     The identifier that GDB uses to refer to the Ada task.

'task-id'
     The identifier that the target uses to refer to the Ada task.

'thread-id'
     The global thread identifier of the thread corresponding to the Ada
     task.

     This field should always exist, as Ada tasks are always implemented
     on top of a thread.  But if GDB cannot find this corresponding
     thread for any reason, the field is omitted.

'parent-id'
     This field exists only when the task was created by another task.
     In this case, it provides the ID of the parent task.

'priority'
     The base priority of the task.

'state'
     The current state of the task.  For a detailed description of the
     possible states, see *note Ada Tasks::.

'name'
     The name of the task.

Example
.......

     -ada-task-info
     ^done,tasks={nr_rows="3",nr_cols="8",
     hdr=[{width="1",alignment="-1",col_name="current",colhdr=""},
     {width="3",alignment="1",col_name="id",colhdr="ID"},
     {width="9",alignment="1",col_name="task-id",colhdr="TID"},
     {width="4",alignment="1",col_name="thread-id",colhdr=""},
     {width="4",alignment="1",col_name="parent-id",colhdr="P-ID"},
     {width="3",alignment="1",col_name="priority",colhdr="Pri"},
     {width="22",alignment="-1",col_name="state",colhdr="State"},
     {width="1",alignment="2",col_name="name",colhdr="Name"}],
     body=[{current="*",id="1",task-id="   644010",thread-id="1",priority="48",
     state="Child Termination Wait",name="main_task"}]}
     (gdb)


File: gdb.info,  Node: GDB/MI Program Execution,  Next: GDB/MI Stack Manipulation,  Prev: GDB/MI Ada Tasking Commands,  Up: GDB/MI

27.13 GDB/MI Program Execution
==============================

These are the asynchronous commands which generate the out-of-band
record '*stopped'.  Currently GDB only really executes asynchronously
with remote targets and this interaction is mimicked in other cases.

The '-exec-continue' Command
----------------------------

Synopsis
........

      -exec-continue [--reverse] [--all|--thread-group N]

   Resumes the execution of the inferior program, which will continue to
execute until it reaches a debugger stop event.  If the '--reverse'
option is specified, execution resumes in reverse until it reaches a
stop event.  Stop events may include
   * breakpoints or watchpoints
   * signals or exceptions
   * the end of the process (or its beginning under '--reverse')
   * the end or beginning of a replay log if one is being used.
   In all-stop mode (*note All-Stop Mode::), may resume only one thread,
or all threads, depending on the value of the 'scheduler-locking'
variable.  If '--all' is specified, all threads (in all inferiors) will
be resumed.  The '--all' option is ignored in all-stop mode.  If the
'--thread-group' options is specified, then all threads in that thread
group are resumed.

GDB Command
...........

The corresponding GDB corresponding is 'continue'.

Example
.......

     -exec-continue
     ^running
     (gdb)
     @Hello world
     *stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame={
     func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c",
     line="13"}
     (gdb)

The '-exec-finish' Command
--------------------------

Synopsis
........

      -exec-finish [--reverse]

   Resumes the execution of the inferior program until the current
function is exited.  Displays the results returned by the function.  If
the '--reverse' option is specified, resumes the reverse execution of
the inferior program until the point where current function was called.

GDB Command
...........

The corresponding GDB command is 'finish'.

Example
.......

Function returning 'void'.

     -exec-finish
     ^running
     (gdb)
     @hello from foo
     *stopped,reason="function-finished",frame={func="main",args=[],
     file="hello.c",fullname="/home/foo/bar/hello.c",line="7"}
     (gdb)

   Function returning other than 'void'.  The name of the internal GDB
variable storing the result is printed, together with the value itself.

     -exec-finish
     ^running
     (gdb)
     *stopped,reason="function-finished",frame={addr="0x000107b0",func="foo",
     args=[{name="a",value="1"],{name="b",value="9"}},
     file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     gdb-result-var="$1",return-value="0"
     (gdb)

The '-exec-interrupt' Command
-----------------------------

Synopsis
........

      -exec-interrupt [--all|--thread-group N]

   Interrupts the background execution of the target.  Note how the
token associated with the stop message is the one for the execution
command that has been interrupted.  The token for the interrupt itself
only appears in the '^done' output.  If the user is trying to interrupt
a non-running program, an error message will be printed.

   Note that when asynchronous execution is enabled, this command is
asynchronous just like other execution commands.  That is, first the
'^done' response will be printed, and the target stop will be reported
after that using the '*stopped' notification.

   In non-stop mode, only the context thread is interrupted by default.
All threads (in all inferiors) will be interrupted if the '--all' option
is specified.  If the '--thread-group' option is specified, all threads
in that group will be interrupted.

GDB Command
...........

The corresponding GDB command is 'interrupt'.

Example
.......

     (gdb)
     111-exec-continue
     111^running

     (gdb)
     222-exec-interrupt
     222^done
     (gdb)
     111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
     frame={addr="0x00010140",func="foo",args=[],file="try.c",
     fullname="/home/foo/bar/try.c",line="13"}
     (gdb)

     (gdb)
     -exec-interrupt
     ^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
     (gdb)

The '-exec-jump' Command
------------------------

Synopsis
........

      -exec-jump LOCATION

   Resumes execution of the inferior program at the location specified
by parameter.  *Note Specify Location::, for a description of the
different forms of LOCATION.

GDB Command
...........

The corresponding GDB command is 'jump'.

Example
.......

     -exec-jump foo.c:10
     *running,thread-id="all"
     ^running

The '-exec-next' Command
------------------------

Synopsis
........

      -exec-next [--reverse]

   Resumes execution of the inferior program, stopping when the
beginning of the next source line is reached.

   If the '--reverse' option is specified, resumes reverse execution of
the inferior program, stopping at the beginning of the previous source
line.  If you issue this command on the first line of a function, it
will take you back to the caller of that function, to the source line
where the function was called.

GDB Command
...........

The corresponding GDB command is 'next'.

Example
.......

     -exec-next
     ^running
     (gdb)
     *stopped,reason="end-stepping-range",line="8",file="hello.c"
     (gdb)

The '-exec-next-instruction' Command
------------------------------------

Synopsis
........

      -exec-next-instruction [--reverse]

   Executes one machine instruction.  If the instruction is a function
call, continues until the function returns.  If the program stops at an
instruction in the middle of a source line, the address will be printed
as well.

   If the '--reverse' option is specified, resumes reverse execution of
the inferior program, stopping at the previous instruction.  If the
previously executed instruction was a return from another function, it
will continue to execute in reverse until the call to that function
(from the current stack frame) is reached.

GDB Command
...........

The corresponding GDB command is 'nexti'.

Example
.......

     (gdb)
     -exec-next-instruction
     ^running

     (gdb)
     *stopped,reason="end-stepping-range",
     addr="0x000100d4",line="5",file="hello.c"
     (gdb)

The '-exec-return' Command
--------------------------

Synopsis
........

      -exec-return

   Makes current function return immediately.  Doesn't execute the
inferior.  Displays the new current frame.

GDB Command
...........

The corresponding GDB command is 'return'.

Example
.......

     (gdb)
     200-break-insert callee4
     200^done,bkpt={number="1",addr="0x00010734",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
     (gdb)
     000-exec-run
     000^running
     (gdb)
     000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
     frame={func="callee4",args=[],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
     (gdb)
     205-break-delete
     205^done
     (gdb)
     111-exec-return
     111^done,frame={level="0",func="callee3",
     args=[{name="strarg",
     value="0x11940 \"A string argument.\""}],
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
     (gdb)

The '-exec-run' Command
-----------------------

Synopsis
........

      -exec-run [ --all | --thread-group N ] [ --start ]

   Starts execution of the inferior from the beginning.  The inferior
executes until either a breakpoint is encountered or the program exits.
In the latter case the output will include an exit code, if the program
has exited exceptionally.

   When neither the '--all' nor the '--thread-group' option is
specified, the current inferior is started.  If the '--thread-group'
option is specified, it should refer to a thread group of type
'process', and that thread group will be started.  If the '--all' option
is specified, then all inferiors will be started.

   Using the '--start' option instructs the debugger to stop the
execution at the start of the inferior's main subprogram, following the
same behavior as the 'start' command (*note Starting::).

GDB Command
...........

The corresponding GDB command is 'run'.

Examples
........

     (gdb)
     -break-insert main
     ^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",line="4"}
     (gdb)
     -exec-run
     ^running
     (gdb)
     *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
     frame={func="main",args=[],file="recursive2.c",
     fullname="/home/foo/bar/recursive2.c",line="4"}
     (gdb)

Program exited normally:

     (gdb)
     -exec-run
     ^running
     (gdb)
     x = 55
     *stopped,reason="exited-normally"
     (gdb)

Program exited exceptionally:

     (gdb)
     -exec-run
     ^running
     (gdb)
     x = 55
     *stopped,reason="exited",exit-code="01"
     (gdb)

   Another way the program can terminate is if it receives a signal such
as 'SIGINT'.  In this case, GDB/MI displays this:

     (gdb)
     *stopped,reason="exited-signalled",signal-name="SIGINT",
     signal-meaning="Interrupt"

The '-exec-step' Command
------------------------

Synopsis
........

      -exec-step [--reverse]

   Resumes execution of the inferior program, stopping when the
beginning of the next source line is reached, if the next source line is
not a function call.  If it is, stop at the first instruction of the
called function.  If the '--reverse' option is specified, resumes
reverse execution of the inferior program, stopping at the beginning of
the previously executed source line.

GDB Command
...........

The corresponding GDB command is 'step'.

Example
.......

Stepping into a function:

     -exec-step
     ^running
     (gdb)
     *stopped,reason="end-stepping-range",
     frame={func="foo",args=[{name="a",value="10"},
     {name="b",value="0"}],file="recursive2.c",
     fullname="/home/foo/bar/recursive2.c",line="11"}
     (gdb)

   Regular stepping:

     -exec-step
     ^running
     (gdb)
     *stopped,reason="end-stepping-range",line="14",file="recursive2.c"
     (gdb)

The '-exec-step-instruction' Command
------------------------------------

Synopsis
........

      -exec-step-instruction [--reverse]

   Resumes the inferior which executes one machine instruction.  If the
'--reverse' option is specified, resumes reverse execution of the
inferior program, stopping at the previously executed instruction.  The
output, once GDB has stopped, will vary depending on whether we have
stopped in the middle of a source line or not.  In the former case, the
address at which the program stopped will be printed as well.

GDB Command
...........

The corresponding GDB command is 'stepi'.

Example
.......

     (gdb)
     -exec-step-instruction
     ^running

     (gdb)
     *stopped,reason="end-stepping-range",
     frame={func="foo",args=[],file="try.c",
     fullname="/home/foo/bar/try.c",line="10"}
     (gdb)
     -exec-step-instruction
     ^running

     (gdb)
     *stopped,reason="end-stepping-range",
     frame={addr="0x000100f4",func="foo",args=[],file="try.c",
     fullname="/home/foo/bar/try.c",line="10"}
     (gdb)

The '-exec-until' Command
-------------------------

Synopsis
........

      -exec-until [ LOCATION ]

   Executes the inferior until the LOCATION specified in the argument is
reached.  If there is no argument, the inferior executes until a source
line greater than the current one is reached.  The reason for stopping
in this case will be 'location-reached'.

GDB Command
...........

The corresponding GDB command is 'until'.

Example
.......

     (gdb)
     -exec-until recursive2.c:6
     ^running
     (gdb)
     x = 55
     *stopped,reason="location-reached",frame={func="main",args=[],
     file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6"}
     (gdb)


File: gdb.info,  Node: GDB/MI Stack Manipulation,  Next: GDB/MI Variable Objects,  Prev: GDB/MI Program Execution,  Up: GDB/MI

27.14 GDB/MI Stack Manipulation Commands
========================================

The '-enable-frame-filters' Command
-----------------------------------

     -enable-frame-filters

   GDB allows Python-based frame filters to affect the output of the MI
commands relating to stack traces.  As there is no way to implement this
in a fully backward-compatible way, a front end must request that this
functionality be enabled.

   Once enabled, this feature cannot be disabled.

   Note that if Python support has not been compiled into GDB, this
command will still succeed (and do nothing).

The '-stack-info-frame' Command
-------------------------------

Synopsis
........

      -stack-info-frame

   Get info on the selected frame.

GDB Command
...........

The corresponding GDB command is 'info frame' or 'frame' (without
arguments).

Example
.......

     (gdb)
     -stack-info-frame
     ^done,frame={level="1",addr="0x0001076c",func="callee3",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"}
     (gdb)

The '-stack-info-depth' Command
-------------------------------

Synopsis
........

      -stack-info-depth [ MAX-DEPTH ]

   Return the depth of the stack.  If the integer argument MAX-DEPTH is
specified, do not count beyond MAX-DEPTH frames.

GDB Command
...........

There's no equivalent GDB command.

Example
.......

For a stack with frame levels 0 through 11:

     (gdb)
     -stack-info-depth
     ^done,depth="12"
     (gdb)
     -stack-info-depth 4
     ^done,depth="4"
     (gdb)
     -stack-info-depth 12
     ^done,depth="12"
     (gdb)
     -stack-info-depth 11
     ^done,depth="11"
     (gdb)
     -stack-info-depth 13
     ^done,depth="12"
     (gdb)

The '-stack-list-arguments' Command
-----------------------------------

Synopsis
........

      -stack-list-arguments [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES
         [ LOW-FRAME HIGH-FRAME ]

   Display a list of the arguments for the frames between LOW-FRAME and
HIGH-FRAME (inclusive).  If LOW-FRAME and HIGH-FRAME are not provided,
list the arguments for the whole call stack.  If the two arguments are
equal, show the single frame at the corresponding level.  It is an error
if LOW-FRAME is larger than the actual number of frames.  On the other
hand, HIGH-FRAME may be larger than the actual number of frames, in
which case only existing frames will be returned.

   If PRINT-VALUES is 0 or '--no-values', print only the names of the
variables; if it is 1 or '--all-values', print also their values; and if
it is 2 or '--simple-values', print the name, type and value for simple
data types, and the name and type for arrays, structures and unions.  If
the option '--no-frame-filters' is supplied, then Python frame filters
will not be executed.

   If the '--skip-unavailable' option is specified, arguments that are
not available are not listed.  Partially available arguments are still
displayed, however.

   Use of this command to obtain arguments in a single frame is
deprecated in favor of the '-stack-list-variables' command.

GDB Command
...........

GDB does not have an equivalent command.  'gdbtk' has a 'gdb_get_args'
command which partially overlaps with the functionality of
'-stack-list-arguments'.

Example
.......

     (gdb)
     -stack-list-frames
     ^done,
     stack=[
     frame={level="0",addr="0x00010734",func="callee4",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"},
     frame={level="1",addr="0x0001076c",func="callee3",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"},
     frame={level="2",addr="0x0001078c",func="callee2",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"},
     frame={level="3",addr="0x000107b4",func="callee1",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"},
     frame={level="4",addr="0x000107e0",func="main",
     file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
     fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"}]
     (gdb)
     -stack-list-arguments 0
     ^done,
     stack-args=[
     frame={level="0",args=[]},
     frame={level="1",args=[name="strarg"]},
     frame={level="2",args=[name="intarg",name="strarg"]},
     frame={level="3",args=[name="intarg",name="strarg",name="fltarg"]},
     frame={level="4",args=[]}]
     (gdb)
     -stack-list-arguments 1
     ^done,
     stack-args=[
     frame={level="0",args=[]},
     frame={level="1",
      args=[{name="strarg",value="0x11940 \"A string argument.\""}]},
     frame={level="2",args=[
     {name="intarg",value="2"},
     {name="strarg",value="0x11940 \"A string argument.\""}]},
     {frame={level="3",args=[
     {name="intarg",value="2"},
     {name="strarg",value="0x11940 \"A string argument.\""},
     {name="fltarg",value="3.5"}]},
     frame={level="4",args=[]}]
     (gdb)
     -stack-list-arguments 0 2 2
     ^done,stack-args=[frame={level="2",args=[name="intarg",name="strarg"]}]
     (gdb)
     -stack-list-arguments 1 2 2
     ^done,stack-args=[frame={level="2",
     args=[{name="intarg",value="2"},
     {name="strarg",value="0x11940 \"A string argument.\""}]}]
     (gdb)

The '-stack-list-frames' Command
--------------------------------

Synopsis
........

      -stack-list-frames [ --no-frame-filters LOW-FRAME HIGH-FRAME ]

   List the frames currently on the stack.  For each frame it displays
the following info:

'LEVEL'
     The frame number, 0 being the topmost frame, i.e., the innermost
     function.
'ADDR'
     The '$pc' value for that frame.
'FUNC'
     Function name.
'FILE'
     File name of the source file where the function lives.
'FULLNAME'
     The full file name of the source file where the function lives.
'LINE'
     Line number corresponding to the '$pc'.
'FROM'
     The shared library where this function is defined.  This is only
     given if the frame's function is not known.

   If invoked without arguments, this command prints a backtrace for the
whole stack.  If given two integer arguments, it shows the frames whose
levels are between the two arguments (inclusive).  If the two arguments
are equal, it shows the single frame at the corresponding level.  It is
an error if LOW-FRAME is larger than the actual number of frames.  On
the other hand, HIGH-FRAME may be larger than the actual number of
frames, in which case only existing frames will be returned.  If the
option '--no-frame-filters' is supplied, then Python frame filters will
not be executed.

GDB Command
...........

The corresponding GDB commands are 'backtrace' and 'where'.

Example
.......

Full stack backtrace:

     (gdb)
     -stack-list-frames
     ^done,stack=
     [frame={level="0",addr="0x0001076c",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11"},
     frame={level="1",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="2",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="3",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="4",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="5",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="6",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="7",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="8",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="9",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="10",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="11",addr="0x00010738",func="main",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4"}]
     (gdb)

   Show frames between LOW_FRAME and HIGH_FRAME:

     (gdb)
     -stack-list-frames 3 5
     ^done,stack=
     [frame={level="3",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="4",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
     frame={level="5",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}]
     (gdb)

   Show a single frame:

     (gdb)
     -stack-list-frames 3 3
     ^done,stack=
     [frame={level="3",addr="0x000107a4",func="foo",
       file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}]
     (gdb)

The '-stack-list-locals' Command
--------------------------------

Synopsis
........

      -stack-list-locals [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES

   Display the local variable names for the selected frame.  If
PRINT-VALUES is 0 or '--no-values', print only the names of the
variables; if it is 1 or '--all-values', print also their values; and if
it is 2 or '--simple-values', print the name, type and value for simple
data types, and the name and type for arrays, structures and unions.  In
this last case, a frontend can immediately display the value of simple
data types and create variable objects for other data types when the
user wishes to explore their values in more detail.  If the option
'--no-frame-filters' is supplied, then Python frame filters will not be
executed.

   If the '--skip-unavailable' option is specified, local variables that
are not available are not listed.  Partially available local variables
are still displayed, however.

   This command is deprecated in favor of the '-stack-list-variables'
command.

GDB Command
...........

'info locals' in GDB, 'gdb_get_locals' in 'gdbtk'.

Example
.......

     (gdb)
     -stack-list-locals 0
     ^done,locals=[name="A",name="B",name="C"]
     (gdb)
     -stack-list-locals --all-values
     ^done,locals=[{name="A",value="1"},{name="B",value="2"},
       {name="C",value="{1, 2, 3}"}]
     -stack-list-locals --simple-values
     ^done,locals=[{name="A",type="int",value="1"},
       {name="B",type="int",value="2"},{name="C",type="int [3]"}]
     (gdb)

The '-stack-list-variables' Command
-----------------------------------

Synopsis
........

      -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES

   Display the names of local variables and function arguments for the
selected frame.  If PRINT-VALUES is 0 or '--no-values', print only the
names of the variables; if it is 1 or '--all-values', print also their
values; and if it is 2 or '--simple-values', print the name, type and
value for simple data types, and the name and type for arrays,
structures and unions.  If the option '--no-frame-filters' is supplied,
then Python frame filters will not be executed.

   If the '--skip-unavailable' option is specified, local variables and
arguments that are not available are not listed.  Partially available
arguments and local variables are still displayed, however.

Example
.......

     (gdb)
     -stack-list-variables --thread 1 --frame 0 --all-values
     ^done,variables=[{name="x",value="11"},{name="s",value="{a = 1, b = 2}"}]
     (gdb)

The '-stack-select-frame' Command
---------------------------------

Synopsis
........

      -stack-select-frame FRAMENUM

   Change the selected frame.  Select a different frame FRAMENUM on the
stack.

   This command in deprecated in favor of passing the '--frame' option
to every command.

GDB Command
...........

The corresponding GDB commands are 'frame', 'up', 'down',
'select-frame', 'up-silent', and 'down-silent'.

Example
.......

     (gdb)
     -stack-select-frame 2
     ^done
     (gdb)


File: gdb.info,  Node: GDB/MI Variable Objects,  Next: GDB/MI Data Manipulation,  Prev: GDB/MI Stack Manipulation,  Up: GDB/MI

27.15 GDB/MI Variable Objects
=============================

Introduction to Variable Objects
--------------------------------

Variable objects are "object-oriented" MI interface for examining and
changing values of expressions.  Unlike some other MI interfaces that
work with expressions, variable objects are specifically designed for
simple and efficient presentation in the frontend.  A variable object is
identified by string name.  When a variable object is created, the
frontend specifies the expression for that variable object.  The
expression can be a simple variable, or it can be an arbitrary complex
expression, and can even involve CPU registers.  After creating a
variable object, the frontend can invoke other variable object
operations--for example to obtain or change the value of a variable
object, or to change display format.

   Variable objects have hierarchical tree structure.  Any variable
object that corresponds to a composite type, such as structure in C, has
a number of child variable objects, for example corresponding to each
element of a structure.  A child variable object can itself have
children, recursively.  Recursion ends when we reach leaf variable
objects, which always have built-in types.  Child variable objects are
created only by explicit request, so if a frontend is not interested in
the children of a particular variable object, no child will be created.

   For a leaf variable object it is possible to obtain its value as a
string, or set the value from a string.  String value can be also
obtained for a non-leaf variable object, but it's generally a string
that only indicates the type of the object, and does not list its
contents.  Assignment to a non-leaf variable object is not allowed.

   A frontend does not need to read the values of all variable objects
each time the program stops.  Instead, MI provides an update command
that lists all variable objects whose values has changed since the last
update operation.  This considerably reduces the amount of data that
must be transferred to the frontend.  As noted above, children variable
objects are created on demand, and only leaf variable objects have a
real value.  As result, gdb will read target memory only for leaf
variables that frontend has created.

   The automatic update is not always desirable.  For example, a
frontend might want to keep a value of some expression for future
reference, and never update it.  For another example, fetching memory is
relatively slow for embedded targets, so a frontend might want to
disable automatic update for the variables that are either not visible
on the screen, or "closed".  This is possible using so called "frozen
variable objects".  Such variable objects are never implicitly updated.

   Variable objects can be either "fixed" or "floating".  For the fixed
variable object, the expression is parsed when the variable object is
created, including associating identifiers to specific variables.  The
meaning of expression never changes.  For a floating variable object the
values of variables whose names appear in the expressions are
re-evaluated every time in the context of the current frame.  Consider
this example:

     void do_work(...)
     {
             struct work_state state;

             if (...)
                do_work(...);
     }

   If a fixed variable object for the 'state' variable is created in
this function, and we enter the recursive call, the variable object will
report the value of 'state' in the top-level 'do_work' invocation.  On
the other hand, a floating variable object will report the value of
'state' in the current frame.

   If an expression specified when creating a fixed variable object
refers to a local variable, the variable object becomes bound to the
thread and frame in which the variable object is created.  When such
variable object is updated, GDB makes sure that the thread/frame
combination the variable object is bound to still exists, and
re-evaluates the variable object in context of that thread/frame.

   The following is the complete set of GDB/MI operations defined to
access this functionality:

*Operation*                   *Description*
                              
'-enable-pretty-printing'     enable Python-based pretty-printing
'-var-create'                 create a variable object
'-var-delete'                 delete the variable object and/or its
                              children
'-var-set-format'             set the display format of this variable
'-var-show-format'            show the display format of this variable
'-var-info-num-children'      tells how many children this object has
'-var-list-children'          return a list of the object's children
'-var-info-type'              show the type of this variable object
'-var-info-expression'        print parent-relative expression that
                              this variable object represents
'-var-info-path-expression'   print full expression that this variable
                              object represents
'-var-show-attributes'        is this variable editable?  does it exist
                              here?
'-var-evaluate-expression'    get the value of this variable
'-var-assign'                 set the value of this variable
'-var-update'                 update the variable and its children
'-var-set-frozen'             set frozeness attribute
'-var-set-update-range'       set range of children to display on
                              update

   In the next subsection we describe each operation in detail and
suggest how it can be used.

Description And Use of Operations on Variable Objects
-----------------------------------------------------

The '-enable-pretty-printing' Command
-------------------------------------

     -enable-pretty-printing

   GDB allows Python-based visualizers to affect the output of the MI
variable object commands.  However, because there was no way to
implement this in a fully backward-compatible way, a front end must
request that this functionality be enabled.

   Once enabled, this feature cannot be disabled.

   Note that if Python support has not been compiled into GDB, this
command will still succeed (and do nothing).

   This feature is currently (as of GDB 7.0) experimental, and may work
differently in future versions of GDB.

The '-var-create' Command
-------------------------

Synopsis
........

      -var-create {NAME | "-"}
         {FRAME-ADDR | "*" | "@"} EXPRESSION

   This operation creates a variable object, which allows the monitoring
of a variable, the result of an expression, a memory cell or a CPU
register.

   The NAME parameter is the string by which the object can be
referenced.  It must be unique.  If '-' is specified, the varobj system
will generate a string "varNNNNNN" automatically.  It will be unique
provided that one does not specify NAME of that format.  The command
fails if a duplicate name is found.

   The frame under which the expression should be evaluated can be
specified by FRAME-ADDR.  A '*' indicates that the current frame should
be used.  A '@' indicates that a floating variable object must be
created.

   EXPRESSION is any expression valid on the current language set (must
not begin with a '*'), or one of the following:

   * '*ADDR', where ADDR is the address of a memory cell

   * '*ADDR-ADDR' -- a memory address range (TBD)

   * '$REGNAME' -- a CPU register name

   A varobj's contents may be provided by a Python-based pretty-printer.
In this case the varobj is known as a "dynamic varobj".  Dynamic varobjs
have slightly different semantics in some cases.  If the
'-enable-pretty-printing' command is not sent, then GDB will never
create a dynamic varobj.  This ensures backward compatibility for
existing clients.

Result
......

This operation returns attributes of the newly-created varobj.  These
are:

'name'
     The name of the varobj.

'numchild'
     The number of children of the varobj.  This number is not
     necessarily reliable for a dynamic varobj.  Instead, you must
     examine the 'has_more' attribute.

'value'
     The varobj's scalar value.  For a varobj whose type is some sort of
     aggregate (e.g., a 'struct'), or for a dynamic varobj, this value
     will not be interesting.

'type'
     The varobj's type.  This is a string representation of the type, as
     would be printed by the GDB CLI. If 'print object' (*note set print
     object: Print Settings.) is set to 'on', the _actual_ (derived)
     type of the object is shown rather than the _declared_ one.

'thread-id'
     If a variable object is bound to a specific thread, then this is
     the thread's global identifier.

'has_more'
     For a dynamic varobj, this indicates whether there appear to be any
     children available.  For a non-dynamic varobj, this will be 0.

'dynamic'
     This attribute will be present and have the value '1' if the varobj
     is a dynamic varobj.  If the varobj is not a dynamic varobj, then
     this attribute will not be present.

'displayhint'
     A dynamic varobj can supply a display hint to the front end.  The
     value comes directly from the Python pretty-printer object's
     'display_hint' method.  *Note Pretty Printing API::.

   Typical output will look like this:

      name="NAME",numchild="N",type="TYPE",thread-id="M",
       has_more="HAS_MORE"

The '-var-delete' Command
-------------------------

Synopsis
........

      -var-delete [ -c ] NAME

   Deletes a previously created variable object and all of its children.
With the '-c' option, just deletes the children.

   Returns an error if the object NAME is not found.

The '-var-set-format' Command
-----------------------------

Synopsis
........

      -var-set-format NAME FORMAT-SPEC

   Sets the output format for the value of the object NAME to be
FORMAT-SPEC.

   The syntax for the FORMAT-SPEC is as follows:

      FORMAT-SPEC ==>
      {binary | decimal | hexadecimal | octal | natural | zero-hexadecimal}

   The natural format is the default format choosen automatically based
on the variable type (like decimal for an 'int', hex for pointers,
etc.).

   The zero-hexadecimal format has a representation similar to
hexadecimal but with padding zeroes to the left of the value.  For
example, a 32-bit hexadecimal value of 0x1234 would be represented as
0x00001234 in the zero-hexadecimal format.

   For a variable with children, the format is set only on the variable
itself, and the children are not affected.

The '-var-show-format' Command
------------------------------

Synopsis
........

      -var-show-format NAME

   Returns the format used to display the value of the object NAME.

      FORMAT ==>
      FORMAT-SPEC

The '-var-info-num-children' Command
------------------------------------

Synopsis
........

      -var-info-num-children NAME

   Returns the number of children of a variable object NAME:

      numchild=N

   Note that this number is not completely reliable for a dynamic
varobj.  It will return the current number of children, but more
children may be available.

The '-var-list-children' Command
--------------------------------

Synopsis
........

      -var-list-children [PRINT-VALUES] NAME [FROM TO]

   Return a list of the children of the specified variable object and
create variable objects for them, if they do not already exist.  With a
single argument or if PRINT-VALUES has a value of 0 or '--no-values',
print only the names of the variables; if PRINT-VALUES is 1 or
'--all-values', also print their values; and if it is 2 or
'--simple-values' print the name and value for simple data types and
just the name for arrays, structures and unions.

   FROM and TO, if specified, indicate the range of children to report.
If FROM or TO is less than zero, the range is reset and all children
will be reported.  Otherwise, children starting at FROM (zero-based) and
up to and excluding TO will be reported.

   If a child range is requested, it will only affect the current call
to '-var-list-children', but not future calls to '-var-update'.  For
this, you must instead use '-var-set-update-range'.  The intent of this
approach is to enable a front end to implement any update approach it
likes; for example, scrolling a view may cause the front end to request
more children with '-var-list-children', and then the front end could
call '-var-set-update-range' with a different range to ensure that
future updates are restricted to just the visible items.

   For each child the following results are returned:

NAME
     Name of the variable object created for this child.

EXP
     The expression to be shown to the user by the front end to
     designate this child.  For example this may be the name of a
     structure member.

     For a dynamic varobj, this value cannot be used to form an
     expression.  There is no way to do this at all with a dynamic
     varobj.

     For C/C++ structures there are several pseudo children returned to
     designate access qualifiers.  For these pseudo children EXP is
     'public', 'private', or 'protected'.  In this case the type and
     value are not present.

     A dynamic varobj will not report the access qualifying
     pseudo-children, regardless of the language.  This information is
     not available at all with a dynamic varobj.

NUMCHILD
     Number of children this child has.  For a dynamic varobj, this will
     be 0.

TYPE
     The type of the child.  If 'print object' (*note set print object:
     Print Settings.) is set to 'on', the _actual_ (derived) type of the
     object is shown rather than the _declared_ one.

VALUE
     If values were requested, this is the value.

THREAD-ID
     If this variable object is associated with a thread, this is the
     thread's global thread id.  Otherwise this result is not present.

FROZEN
     If the variable object is frozen, this variable will be present
     with a value of 1.

DISPLAYHINT
     A dynamic varobj can supply a display hint to the front end.  The
     value comes directly from the Python pretty-printer object's
     'display_hint' method.  *Note Pretty Printing API::.

DYNAMIC
     This attribute will be present and have the value '1' if the varobj
     is a dynamic varobj.  If the varobj is not a dynamic varobj, then
     this attribute will not be present.

   The result may have its own attributes:

'displayhint'
     A dynamic varobj can supply a display hint to the front end.  The
     value comes directly from the Python pretty-printer object's
     'display_hint' method.  *Note Pretty Printing API::.

'has_more'
     This is an integer attribute which is nonzero if there are children
     remaining after the end of the selected range.

Example
.......

     (gdb)
      -var-list-children n
      ^done,numchild=N,children=[child={name=NAME,exp=EXP,
      numchild=N,type=TYPE},(repeats N times)]
     (gdb)
      -var-list-children --all-values n
      ^done,numchild=N,children=[child={name=NAME,exp=EXP,
      numchild=N,value=VALUE,type=TYPE},(repeats N times)]

The '-var-info-type' Command
----------------------------

Synopsis
........

      -var-info-type NAME

   Returns the type of the specified variable NAME.  The type is
returned as a string in the same format as it is output by the GDB CLI:

      type=TYPENAME

The '-var-info-expression' Command
----------------------------------

Synopsis
........

      -var-info-expression NAME

   Returns a string that is suitable for presenting this variable object
in user interface.  The string is generally not valid expression in the
current language, and cannot be evaluated.

   For example, if 'a' is an array, and variable object 'A' was created
for 'a', then we'll get this output:

     (gdb) -var-info-expression A.1
     ^done,lang="C",exp="1"

Here, the value of 'lang' is the language name, which can be found in
*note Supported Languages::.

   Note that the output of the '-var-list-children' command also
includes those expressions, so the '-var-info-expression' command is of
limited use.

The '-var-info-path-expression' Command
---------------------------------------

Synopsis
........

      -var-info-path-expression NAME

   Returns an expression that can be evaluated in the current context
and will yield the same value that a variable object has.  Compare this
with the '-var-info-expression' command, which result can be used only
for UI presentation.  Typical use of the '-var-info-path-expression'
command is creating a watchpoint from a variable object.

   This command is currently not valid for children of a dynamic varobj,
and will give an error when invoked on one.

   For example, suppose 'C' is a C++ class, derived from class 'Base',
and that the 'Base' class has a member called 'm_size'.  Assume a
variable 'c' is has the type of 'C' and a variable object 'C' was
created for variable 'c'.  Then, we'll get this output:
     (gdb) -var-info-path-expression C.Base.public.m_size
     ^done,path_expr=((Base)c).m_size)

The '-var-show-attributes' Command
----------------------------------

Synopsis
........

      -var-show-attributes NAME

   List attributes of the specified variable object NAME:

      status=ATTR [ ( ,ATTR )* ]

where ATTR is '{ { editable | noneditable } | TBD }'.

The '-var-evaluate-expression' Command
--------------------------------------

Synopsis
........

      -var-evaluate-expression [-f FORMAT-SPEC] NAME

   Evaluates the expression that is represented by the specified
variable object and returns its value as a string.  The format of the
string can be specified with the '-f' option.  The possible values of
this option are the same as for '-var-set-format' (*note
-var-set-format::).  If the '-f' option is not specified, the current
display format will be used.  The current display format can be changed
using the '-var-set-format' command.

      value=VALUE

   Note that one must invoke '-var-list-children' for a variable before
the value of a child variable can be evaluated.

The '-var-assign' Command
-------------------------

Synopsis
........

      -var-assign NAME EXPRESSION

   Assigns the value of EXPRESSION to the variable object specified by
NAME.  The object must be 'editable'.  If the variable's value is
altered by the assign, the variable will show up in any subsequent
'-var-update' list.

Example
.......

     (gdb)
     -var-assign var1 3
     ^done,value="3"
     (gdb)
     -var-update *
     ^done,changelist=[{name="var1",in_scope="true",type_changed="false"}]
     (gdb)

The '-var-update' Command
-------------------------

Synopsis
........

      -var-update [PRINT-VALUES] {NAME | "*"}

   Reevaluate the expressions corresponding to the variable object NAME
and all its direct and indirect children, and return the list of
variable objects whose values have changed; NAME must be a root variable
object.  Here, "changed" means that the result of
'-var-evaluate-expression' before and after the '-var-update' is
different.  If '*' is used as the variable object names, all existing
variable objects are updated, except for frozen ones (*note
-var-set-frozen::).  The option PRINT-VALUES determines whether both
names and values, or just names are printed.  The possible values of
this option are the same as for '-var-list-children' (*note
-var-list-children::).  It is recommended to use the '--all-values'
option, to reduce the number of MI commands needed on each program stop.

   With the '*' parameter, if a variable object is bound to a currently
running thread, it will not be updated, without any diagnostic.

   If '-var-set-update-range' was previously used on a varobj, then only
the selected range of children will be reported.

   '-var-update' reports all the changed varobjs in a tuple named
'changelist'.

   Each item in the change list is itself a tuple holding:

'name'
     The name of the varobj.

'value'
     If values were requested for this update, then this field will be
     present and will hold the value of the varobj.

'in_scope'
     This field is a string which may take one of three values:

     '"true"'
          The variable object's current value is valid.

     '"false"'
          The variable object does not currently hold a valid value but
          it may hold one in the future if its associated expression
          comes back into scope.

     '"invalid"'
          The variable object no longer holds a valid value.  This can
          occur when the executable file being debugged has changed,
          either through recompilation or by using the GDB 'file'
          command.  The front end should normally choose to delete these
          variable objects.

     In the future new values may be added to this list so the front
     should be prepared for this possibility.  *Note GDB/MI Development
     and Front Ends: GDB/MI Development and Front Ends.

'type_changed'
     This is only present if the varobj is still valid.  If the type
     changed, then this will be the string 'true'; otherwise it will be
     'false'.

     When a varobj's type changes, its children are also likely to have
     become incorrect.  Therefore, the varobj's children are
     automatically deleted when this attribute is 'true'.  Also, the
     varobj's update range, when set using the '-var-set-update-range'
     command, is unset.

'new_type'
     If the varobj's type changed, then this field will be present and
     will hold the new type.

'new_num_children'
     For a dynamic varobj, if the number of children changed, or if the
     type changed, this will be the new number of children.

     The 'numchild' field in other varobj responses is generally not
     valid for a dynamic varobj - it will show the number of children
     that GDB knows about, but because dynamic varobjs lazily
     instantiate their children, this will not reflect the number of
     children which may be available.

     The 'new_num_children' attribute only reports changes to the number
     of children known by GDB.  This is the only way to detect whether
     an update has removed children (which necessarily can only happen
     at the end of the update range).

'displayhint'
     The display hint, if any.

'has_more'
     This is an integer value, which will be 1 if there are more
     children available outside the varobj's update range.

'dynamic'
     This attribute will be present and have the value '1' if the varobj
     is a dynamic varobj.  If the varobj is not a dynamic varobj, then
     this attribute will not be present.

'new_children'
     If new children were added to a dynamic varobj within the selected
     update range (as set by '-var-set-update-range'), then they will be
     listed in this attribute.

Example
.......

     (gdb)
     -var-assign var1 3
     ^done,value="3"
     (gdb)
     -var-update --all-values var1
     ^done,changelist=[{name="var1",value="3",in_scope="true",
     type_changed="false"}]
     (gdb)

The '-var-set-frozen' Command
-----------------------------

Synopsis
........

      -var-set-frozen NAME FLAG

   Set the frozenness flag on the variable object NAME.  The FLAG
parameter should be either '1' to make the variable frozen or '0' to
make it unfrozen.  If a variable object is frozen, then neither itself,
nor any of its children, are implicitly updated by '-var-update' of a
parent variable or by '-var-update *'.  Only '-var-update' of the
variable itself will update its value and values of its children.  After
a variable object is unfrozen, it is implicitly updated by all
subsequent '-var-update' operations.  Unfreezing a variable does not
update it, only subsequent '-var-update' does.

Example
.......

     (gdb)
     -var-set-frozen V 1
     ^done
     (gdb)

The '-var-set-update-range' command
-----------------------------------

Synopsis
........

      -var-set-update-range NAME FROM TO

   Set the range of children to be returned by future invocations of
'-var-update'.

   FROM and TO indicate the range of children to report.  If FROM or TO
is less than zero, the range is reset and all children will be reported.
Otherwise, children starting at FROM (zero-based) and up to and
excluding TO will be reported.

Example
.......

     (gdb)
     -var-set-update-range V 1 2
     ^done

The '-var-set-visualizer' command
---------------------------------

Synopsis
........

      -var-set-visualizer NAME VISUALIZER

   Set a visualizer for the variable object NAME.

   VISUALIZER is the visualizer to use.  The special value 'None' means
to disable any visualizer in use.

   If not 'None', VISUALIZER must be a Python expression.  This
expression must evaluate to a callable object which accepts a single
argument.  GDB will call this object with the value of the varobj NAME
as an argument (this is done so that the same Python pretty-printing
code can be used for both the CLI and MI). When called, this object must
return an object which conforms to the pretty-printing interface (*note
Pretty Printing API::).

   The pre-defined function 'gdb.default_visualizer' may be used to
select a visualizer by following the built-in process (*note Selecting
Pretty-Printers::).  This is done automatically when a varobj is
created, and so ordinarily is not needed.

   This feature is only available if Python support is enabled.  The MI
command '-list-features' (*note GDB/MI Support Commands::) can be used
to check this.

Example
.......

Resetting the visualizer:

     (gdb)
     -var-set-visualizer V None
     ^done

   Reselecting the default (type-based) visualizer:

     (gdb)
     -var-set-visualizer V gdb.default_visualizer
     ^done

   Suppose 'SomeClass' is a visualizer class.  A lambda expression can
be used to instantiate this class for a varobj:

     (gdb)
     -var-set-visualizer V "lambda val: SomeClass()"
     ^done


File: gdb.info,  Node: GDB/MI Data Manipulation,  Next: GDB/MI Tracepoint Commands,  Prev: GDB/MI Variable Objects,  Up: GDB/MI

27.16 GDB/MI Data Manipulation
==============================

This section describes the GDB/MI commands that manipulate data: examine
memory and registers, evaluate expressions, etc.

   For details about what an addressable memory unit is, *note
addressable memory unit::.

The '-data-disassemble' Command
-------------------------------

Synopsis
........

      -data-disassemble
         [ -s START-ADDR -e END-ADDR ]
       | [ -f FILENAME -l LINENUM [ -n LINES ] ]
       -- MODE

Where:

'START-ADDR'
     is the beginning address (or '$pc')
'END-ADDR'
     is the end address
'FILENAME'
     is the name of the file to disassemble
'LINENUM'
     is the line number to disassemble around
'LINES'
     is the number of disassembly lines to be produced.  If it is -1,
     the whole function will be disassembled, in case no END-ADDR is
     specified.  If END-ADDR is specified as a non-zero value, and LINES
     is lower than the number of disassembly lines between START-ADDR
     and END-ADDR, only LINES lines are displayed; if LINES is higher
     than the number of lines between START-ADDR and END-ADDR, only the
     lines up to END-ADDR are displayed.
'MODE'
     is one of:
        * 0 disassembly only
        * 1 mixed source and disassembly (deprecated)
        * 2 disassembly with raw opcodes
        * 3 mixed source and disassembly with raw opcodes (deprecated)
        * 4 mixed source and disassembly
        * 5 mixed source and disassembly with raw opcodes

     Modes 1 and 3 are deprecated.  The output is "source centric" which
     hasn't proved useful in practice.  *Note Machine Code::, for a
     discussion of the difference between '/m' and '/s' output of the
     'disassemble' command.

Result
......

The result of the '-data-disassemble' command will be a list named
'asm_insns', the contents of this list depend on the MODE used with the
'-data-disassemble' command.

   For modes 0 and 2 the 'asm_insns' list contains tuples with the
following fields:

'address'
     The address at which this instruction was disassembled.

'func-name'
     The name of the function this instruction is within.

'offset'
     The decimal offset in bytes from the start of 'func-name'.

'inst'
     The text disassembly for this 'address'.

'opcodes'
     This field is only present for modes 2, 3 and 5.  This contains the
     raw opcode bytes for the 'inst' field.

   For modes 1, 3, 4 and 5 the 'asm_insns' list contains tuples named
'src_and_asm_line', each of which has the following fields:

'line'
     The line number within 'file'.

'file'
     The file name from the compilation unit.  This might be an absolute
     file name or a relative file name depending on the compile command
     used.

'fullname'
     Absolute file name of 'file'.  It is converted to a canonical form
     using the source file search path (*note Specifying Source
     Directories: Source Path.) and after resolving all the symbolic
     links.

     If the source file is not found this field will contain the path as
     present in the debug information.

'line_asm_insn'
     This is a list of tuples containing the disassembly for 'line' in
     'file'.  The fields of each tuple are the same as for
     '-data-disassemble' in MODE 0 and 2, so 'address', 'func-name',
     'offset', 'inst', and optionally 'opcodes'.

   Note that whatever included in the 'inst' field, is not manipulated
directly by GDB/MI, i.e., it is not possible to adjust its format.

GDB Command
...........

The corresponding GDB command is 'disassemble'.

Example
.......

Disassemble from the current value of '$pc' to '$pc + 20':

     (gdb)
     -data-disassemble -s $pc -e "$pc + 20" -- 0
     ^done,
     asm_insns=[
     {address="0x000107c0",func-name="main",offset="4",
     inst="mov  2, %o0"},
     {address="0x000107c4",func-name="main",offset="8",
     inst="sethi  %hi(0x11800), %o2"},
     {address="0x000107c8",func-name="main",offset="12",
     inst="or  %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"},
     {address="0x000107cc",func-name="main",offset="16",
     inst="sethi  %hi(0x11800), %o2"},
     {address="0x000107d0",func-name="main",offset="20",
     inst="or  %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"}]
     (gdb)

   Disassemble the whole 'main' function.  Line 32 is part of 'main'.

     -data-disassemble -f basics.c -l 32 -- 0
     ^done,asm_insns=[
     {address="0x000107bc",func-name="main",offset="0",
     inst="save  %sp, -112, %sp"},
     {address="0x000107c0",func-name="main",offset="4",
     inst="mov   2, %o0"},
     {address="0x000107c4",func-name="main",offset="8",
     inst="sethi %hi(0x11800), %o2"},
     [...]
     {address="0x0001081c",func-name="main",offset="96",inst="ret "},
     {address="0x00010820",func-name="main",offset="100",inst="restore "}]
     (gdb)

   Disassemble 3 instructions from the start of 'main':

     (gdb)
     -data-disassemble -f basics.c -l 32 -n 3 -- 0
     ^done,asm_insns=[
     {address="0x000107bc",func-name="main",offset="0",
     inst="save  %sp, -112, %sp"},
     {address="0x000107c0",func-name="main",offset="4",
     inst="mov  2, %o0"},
     {address="0x000107c4",func-name="main",offset="8",
     inst="sethi  %hi(0x11800), %o2"}]
     (gdb)

   Disassemble 3 instructions from the start of 'main' in mixed mode:

     (gdb)
     -data-disassemble -f basics.c -l 32 -n 3 -- 1
     ^done,asm_insns=[
     src_and_asm_line={line="31",
     file="../../../src/gdb/testsuite/gdb.mi/basics.c",
     fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c",
     line_asm_insn=[{address="0x000107bc",
     func-name="main",offset="0",inst="save  %sp, -112, %sp"}]},
     src_and_asm_line={line="32",
     file="../../../src/gdb/testsuite/gdb.mi/basics.c",
     fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c",
     line_asm_insn=[{address="0x000107c0",
     func-name="main",offset="4",inst="mov  2, %o0"},
     {address="0x000107c4",func-name="main",offset="8",
     inst="sethi  %hi(0x11800), %o2"}]}]
     (gdb)

The '-data-evaluate-expression' Command
---------------------------------------

Synopsis
........

      -data-evaluate-expression EXPR

   Evaluate EXPR as an expression.  The expression could contain an
inferior function call.  The function call will execute synchronously.
If the expression contains spaces, it must be enclosed in double quotes.

GDB Command
...........

The corresponding GDB commands are 'print', 'output', and 'call'.  In
'gdbtk' only, there's a corresponding 'gdb_eval' command.

Example
.......

In the following example, the numbers that precede the commands are the
"tokens" described in *note GDB/MI Command Syntax: GDB/MI Command
Syntax.  Notice how GDB/MI returns the same tokens in its output.

     211-data-evaluate-expression A
     211^done,value="1"
     (gdb)
     311-data-evaluate-expression &A
     311^done,value="0xefffeb7c"
     (gdb)
     411-data-evaluate-expression A+3
     411^done,value="4"
     (gdb)
     511-data-evaluate-expression "A + 3"
     511^done,value="4"
     (gdb)

The '-data-list-changed-registers' Command
------------------------------------------

Synopsis
........

      -data-list-changed-registers

   Display a list of the registers that have changed.

GDB Command
...........

GDB doesn't have a direct analog for this command; 'gdbtk' has the
corresponding command 'gdb_changed_register_list'.

Example
.......

On a PPC MBX board:

     (gdb)
     -exec-continue
     ^running

     (gdb)
     *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={
     func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c",
     line="5"}
     (gdb)
     -data-list-changed-registers
     ^done,changed-registers=["0","1","2","4","5","6","7","8","9",
     "10","11","13","14","15","16","17","18","19","20","21","22","23",
     "24","25","26","27","28","30","31","64","65","66","67","69"]
     (gdb)

The '-data-list-register-names' Command
---------------------------------------

Synopsis
........

      -data-list-register-names [ ( REGNO )+ ]

   Show a list of register names for the current target.  If no
arguments are given, it shows a list of the names of all the registers.
If integer numbers are given as arguments, it will print a list of the
names of the registers corresponding to the arguments.  To ensure
consistency between a register name and its number, the output list may
include empty register names.

GDB Command
...........

GDB does not have a command which corresponds to
'-data-list-register-names'.  In 'gdbtk' there is a corresponding
command 'gdb_regnames'.

Example
.......

For the PPC MBX board:
     (gdb)
     -data-list-register-names
     ^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
     "r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
     "r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
     "r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
     "f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
     "f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
     "", "pc","ps","cr","lr","ctr","xer"]
     (gdb)
     -data-list-register-names 1 2 3
     ^done,register-names=["r1","r2","r3"]
     (gdb)

The '-data-list-register-values' Command
----------------------------------------

Synopsis
........

      -data-list-register-values
         [ --skip-unavailable ] FMT [ ( REGNO )*]

   Display the registers' contents.  The format according to which the
registers' contents are to be returned is given by FMT, followed by an
optional list of numbers specifying the registers to display.  A missing
list of numbers indicates that the contents of all the registers must be
returned.  The '--skip-unavailable' option indicates that only the
available registers are to be returned.

   Allowed formats for FMT are:

'x'
     Hexadecimal
'o'
     Octal
't'
     Binary
'd'
     Decimal
'r'
     Raw
'N'
     Natural

GDB Command
...........

The corresponding GDB commands are 'info reg', 'info all-reg', and (in
'gdbtk') 'gdb_fetch_registers'.

Example
.......

For a PPC MBX board (note: line breaks are for readability only, they
don't appear in the actual output):

     (gdb)
     -data-list-register-values r 64 65
     ^done,register-values=[{number="64",value="0xfe00a300"},
     {number="65",value="0x00029002"}]
     (gdb)
     -data-list-register-values x
     ^done,register-values=[{number="0",value="0xfe0043c8"},
     {number="1",value="0x3fff88"},{number="2",value="0xfffffffe"},
     {number="3",value="0x0"},{number="4",value="0xa"},
     {number="5",value="0x3fff68"},{number="6",value="0x3fff58"},
     {number="7",value="0xfe011e98"},{number="8",value="0x2"},
     {number="9",value="0xfa202820"},{number="10",value="0xfa202808"},
     {number="11",value="0x1"},{number="12",value="0x0"},
     {number="13",value="0x4544"},{number="14",value="0xffdfffff"},
     {number="15",value="0xffffffff"},{number="16",value="0xfffffeff"},
     {number="17",value="0xefffffed"},{number="18",value="0xfffffffe"},
     {number="19",value="0xffffffff"},{number="20",value="0xffffffff"},
     {number="21",value="0xffffffff"},{number="22",value="0xfffffff7"},
     {number="23",value="0xffffffff"},{number="24",value="0xffffffff"},
     {number="25",value="0xffffffff"},{number="26",value="0xfffffffb"},
     {number="27",value="0xffffffff"},{number="28",value="0xf7bfffff"},
     {number="29",value="0x0"},{number="30",value="0xfe010000"},
     {number="31",value="0x0"},{number="32",value="0x0"},
     {number="33",value="0x0"},{number="34",value="0x0"},
     {number="35",value="0x0"},{number="36",value="0x0"},
     {number="37",value="0x0"},{number="38",value="0x0"},
     {number="39",value="0x0"},{number="40",value="0x0"},
     {number="41",value="0x0"},{number="42",value="0x0"},
     {number="43",value="0x0"},{number="44",value="0x0"},
     {number="45",value="0x0"},{number="46",value="0x0"},
     {number="47",value="0x0"},{number="48",value="0x0"},
     {number="49",value="0x0"},{number="50",value="0x0"},
     {number="51",value="0x0"},{number="52",value="0x0"},
     {number="53",value="0x0"},{number="54",value="0x0"},
     {number="55",value="0x0"},{number="56",value="0x0"},
     {number="57",value="0x0"},{number="58",value="0x0"},
     {number="59",value="0x0"},{number="60",value="0x0"},
     {number="61",value="0x0"},{number="62",value="0x0"},
     {number="63",value="0x0"},{number="64",value="0xfe00a300"},
     {number="65",value="0x29002"},{number="66",value="0x202f04b5"},
     {number="67",value="0xfe0043b0"},{number="68",value="0xfe00b3e4"},
     {number="69",value="0x20002b03"}]
     (gdb)

The '-data-read-memory' Command
-------------------------------

This command is deprecated, use '-data-read-memory-bytes' instead.

Synopsis
........

      -data-read-memory [ -o BYTE-OFFSET ]
        ADDRESS WORD-FORMAT WORD-SIZE
        NR-ROWS NR-COLS [ ASCHAR ]

where:

'ADDRESS'
     An expression specifying the address of the first memory word to be
     read.  Complex expressions containing embedded white space should
     be quoted using the C convention.

'WORD-FORMAT'
     The format to be used to print the memory words.  The notation is
     the same as for GDB's 'print' command (*note Output Formats: Output
     Formats.).

'WORD-SIZE'
     The size of each memory word in bytes.

'NR-ROWS'
     The number of rows in the output table.

'NR-COLS'
     The number of columns in the output table.

'ASCHAR'
     If present, indicates that each row should include an ASCII dump.
     The value of ASCHAR is used as a padding character when a byte is
     not a member of the printable ASCII character set (printable ASCII
     characters are those whose code is between 32 and 126,
     inclusively).

'BYTE-OFFSET'
     An offset to add to the ADDRESS before fetching memory.

   This command displays memory contents as a table of NR-ROWS by
NR-COLS words, each word being WORD-SIZE bytes.  In total, 'NR-ROWS *
NR-COLS * WORD-SIZE' bytes are read (returned as 'total-bytes').  Should
less than the requested number of bytes be returned by the target, the
missing words are identified using 'N/A'.  The number of bytes read from
the target is returned in 'nr-bytes' and the starting address used to
read memory in 'addr'.

   The address of the next/previous row or page is available in
'next-row' and 'prev-row', 'next-page' and 'prev-page'.

GDB Command
...........

The corresponding GDB command is 'x'.  'gdbtk' has 'gdb_get_mem' memory
read command.

Example
.......

Read six bytes of memory starting at 'bytes+6' but then offset by '-6'
bytes.  Format as three rows of two columns.  One byte per word.
Display each word in hex.

     (gdb)
     9-data-read-memory -o -6 -- bytes+6 x 1 3 2
     9^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
     next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
     prev-page="0x0000138a",memory=[
     {addr="0x00001390",data=["0x00","0x01"]},
     {addr="0x00001392",data=["0x02","0x03"]},
     {addr="0x00001394",data=["0x04","0x05"]}]
     (gdb)

   Read two bytes of memory starting at address 'shorts + 64' and
display as a single word formatted in decimal.

     (gdb)
     5-data-read-memory shorts+64 d 2 1 1
     5^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
     next-row="0x00001512",prev-row="0x0000150e",
     next-page="0x00001512",prev-page="0x0000150e",memory=[
     {addr="0x00001510",data=["128"]}]
     (gdb)

   Read thirty two bytes of memory starting at 'bytes+16' and format as
eight rows of four columns.  Include a string encoding with 'x' used as
the non-printable character.

     (gdb)
     4-data-read-memory bytes+16 x 1 8 4 x
     4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
     next-row="0x000013c0",prev-row="0x0000139c",
     next-page="0x000013c0",prev-page="0x00001380",memory=[
     {addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"},
     {addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"},
     {addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"},
     {addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"},
     {addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"},
     {addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"},
     {addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"},
     {addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"}]
     (gdb)

The '-data-read-memory-bytes' Command
-------------------------------------

Synopsis
........

      -data-read-memory-bytes [ -o OFFSET ]
        ADDRESS COUNT

where:

'ADDRESS'
     An expression specifying the address of the first addressable
     memory unit to be read.  Complex expressions containing embedded
     white space should be quoted using the C convention.

'COUNT'
     The number of addressable memory units to read.  This should be an
     integer literal.

'OFFSET'
     The offset relative to ADDRESS at which to start reading.  This
     should be an integer literal.  This option is provided so that a
     frontend is not required to first evaluate address and then perform
     address arithmetics itself.

   This command attempts to read all accessible memory regions in the
specified range.  First, all regions marked as unreadable in the memory
map (if one is defined) will be skipped.  *Note Memory Region
Attributes::.  Second, GDB will attempt to read the remaining regions.
For each one, if reading full region results in an errors, GDB will try
to read a subset of the region.

   In general, every single memory unit in the region may be readable or
not, and the only way to read every readable unit is to try a read at
every address, which is not practical.  Therefore, GDB will attempt to
read all accessible memory units at either beginning or the end of the
region, using a binary division scheme.  This heuristic works well for
reading accross a memory map boundary.  Note that if a region has a
readable range that is neither at the beginning or the end, GDB will not
read it.

   The result record (*note GDB/MI Result Records::) that is output of
the command includes a field named 'memory' whose content is a list of
tuples.  Each tuple represent a successfully read memory block and has
the following fields:

'begin'
     The start address of the memory block, as hexadecimal literal.

'end'
     The end address of the memory block, as hexadecimal literal.

'offset'
     The offset of the memory block, as hexadecimal literal, relative to
     the start address passed to '-data-read-memory-bytes'.

'contents'
     The contents of the memory block, in hex.

GDB Command
...........

The corresponding GDB command is 'x'.

Example
.......

     (gdb)
     -data-read-memory-bytes &a 10
     ^done,memory=[{begin="0xbffff154",offset="0x00000000",
                   end="0xbffff15e",
                   contents="01000000020000000300"}]
     (gdb)

The '-data-write-memory-bytes' Command
--------------------------------------

Synopsis
........

      -data-write-memory-bytes ADDRESS CONTENTS
      -data-write-memory-bytes ADDRESS CONTENTS [COUNT]

where:

'ADDRESS'
     An expression specifying the address of the first addressable
     memory unit to be written.  Complex expressions containing embedded
     white space should be quoted using the C convention.

'CONTENTS'
     The hex-encoded data to write.  It is an error if CONTENTS does not
     represent an integral number of addressable memory units.

'COUNT'
     Optional argument indicating the number of addressable memory units
     to be written.  If COUNT is greater than CONTENTS' length, GDB will
     repeatedly write CONTENTS until it fills COUNT memory units.

GDB Command
...........

There's no corresponding GDB command.

Example
.......

     (gdb)
     -data-write-memory-bytes &a "aabbccdd"
     ^done
     (gdb)

     (gdb)
     -data-write-memory-bytes &a "aabbccdd" 16e
     ^done
     (gdb)


File: gdb.info,  Node: GDB/MI Tracepoint Commands,  Next: GDB/MI Symbol Query,  Prev: GDB/MI Data Manipulation,  Up: GDB/MI

27.17 GDB/MI Tracepoint Commands
================================

The commands defined in this section implement MI support for
tracepoints.  For detailed introduction, see *note Tracepoints::.

The '-trace-find' Command
-------------------------

Synopsis
........

      -trace-find MODE [PARAMETERS...]

   Find a trace frame using criteria defined by MODE and PARAMETERS.
The following table lists permissible modes and their parameters.  For
details of operation, see *note tfind::.

'none'
     No parameters are required.  Stops examining trace frames.

'frame-number'
     An integer is required as parameter.  Selects tracepoint frame with
     that index.

'tracepoint-number'
     An integer is required as parameter.  Finds next trace frame that
     corresponds to tracepoint with the specified number.

'pc'
     An address is required as parameter.  Finds next trace frame that
     corresponds to any tracepoint at the specified address.

'pc-inside-range'
     Two addresses are required as parameters.  Finds next trace frame
     that corresponds to a tracepoint at an address inside the specified
     range.  Both bounds are considered to be inside the range.

'pc-outside-range'
     Two addresses are required as parameters.  Finds next trace frame
     that corresponds to a tracepoint at an address outside the
     specified range.  Both bounds are considered to be inside the
     range.

'line'
     Line specification is required as parameter.  *Note Specify
     Location::.  Finds next trace frame that corresponds to a
     tracepoint at the specified location.

   If 'none' was passed as MODE, the response does not have fields.
Otherwise, the response may have the following fields:

'found'
     This field has either '0' or '1' as the value, depending on whether
     a matching tracepoint was found.

'traceframe'
     The index of the found traceframe.  This field is present iff the
     'found' field has value of '1'.

'tracepoint'
     The index of the found tracepoint.  This field is present iff the
     'found' field has value of '1'.

'frame'
     The information about the frame corresponding to the found trace
     frame.  This field is present only if a trace frame was found.
     *Note GDB/MI Frame Information::, for description of this field.

GDB Command
...........

The corresponding GDB command is 'tfind'.

-trace-define-variable
----------------------

Synopsis
........

      -trace-define-variable NAME [ VALUE ]

   Create trace variable NAME if it does not exist.  If VALUE is
specified, sets the initial value of the specified trace variable to
that value.  Note that the NAME should start with the '$' character.

GDB Command
...........

The corresponding GDB command is 'tvariable'.

The '-trace-frame-collected' Command
------------------------------------

Synopsis
........

      -trace-frame-collected
         [--var-print-values VAR_PVAL]
         [--comp-print-values COMP_PVAL]
         [--registers-format REGFORMAT]
         [--memory-contents]

   This command returns the set of collected objects, register names,
trace state variable names, memory ranges and computed expressions that
have been collected at a particular trace frame.  The optional
parameters to the command affect the output format in different ways.
See the output description table below for more details.

   The reported names can be used in the normal manner to create varobjs
and inspect the objects themselves.  The items returned by this command
are categorized so that it is clear which is a variable, which is a
register, which is a trace state variable, which is a memory range and
which is a computed expression.

   For instance, if the actions were
     collect myVar, myArray[myIndex], myObj.field, myPtr->field, myCount + 2
     collect *(int*)0xaf02bef0@40

the object collected in its entirety would be 'myVar'.  The object
'myArray' would be partially collected, because only the element at
index 'myIndex' would be collected.  The remaining objects would be
computed expressions.

   An example output would be:

     (gdb)
     -trace-frame-collected
     ^done,
       explicit-variables=[{name="myVar",value="1"}],
       computed-expressions=[{name="myArray[myIndex]",value="0"},
                             {name="myObj.field",value="0"},
                             {name="myPtr->field",value="1"},
                             {name="myCount + 2",value="3"},
                             {name="$tvar1 + 1",value="43970027"}],
       registers=[{number="0",value="0x7fe2c6e79ec8"},
                  {number="1",value="0x0"},
                  {number="2",value="0x4"},
                  ...
                  {number="125",value="0x0"}],
       tvars=[{name="$tvar1",current="43970026"}],
       memory=[{address="0x0000000000602264",length="4"},
               {address="0x0000000000615bc0",length="4"}]
     (gdb)

   Where:

'explicit-variables'
     The set of objects that have been collected in their entirety (as
     opposed to collecting just a few elements of an array or a few
     struct members).  For each object, its name and value are printed.
     The '--var-print-values' option affects how or whether the value
     field is output.  If VAR_PVAL is 0, then print only the names; if
     it is 1, print also their values; and if it is 2, print the name,
     type and value for simple data types, and the name and type for
     arrays, structures and unions.

'computed-expressions'
     The set of computed expressions that have been collected at the
     current trace frame.  The '--comp-print-values' option affects this
     set like the '--var-print-values' option affects the
     'explicit-variables' set.  See above.

'registers'
     The registers that have been collected at the current trace frame.
     For each register collected, the name and current value are
     returned.  The value is formatted according to the
     '--registers-format' option.  See the '-data-list-register-values'
     command for a list of the allowed formats.  The default is 'x'.

'tvars'
     The trace state variables that have been collected at the current
     trace frame.  For each trace state variable collected, the name and
     current value are returned.

'memory'
     The set of memory ranges that have been collected at the current
     trace frame.  Its content is a list of tuples.  Each tuple
     represents a collected memory range and has the following fields:

     'address'
          The start address of the memory range, as hexadecimal literal.

     'length'
          The length of the memory range, as decimal literal.

     'contents'
          The contents of the memory block, in hex.  This field is only
          present if the '--memory-contents' option is specified.

GDB Command
...........

There is no corresponding GDB command.

Example
.......

-trace-list-variables
---------------------

Synopsis
........

      -trace-list-variables

   Return a table of all defined trace variables.  Each element of the
table has the following fields:

'name'
     The name of the trace variable.  This field is always present.

'initial'
     The initial value.  This is a 64-bit signed integer.  This field is
     always present.

'current'
     The value the trace variable has at the moment.  This is a 64-bit
     signed integer.  This field is absent iff current value is not
     defined, for example if the trace was never run, or is presently
     running.

GDB Command
...........

The corresponding GDB command is 'tvariables'.

Example
.......

     (gdb)
     -trace-list-variables
     ^done,trace-variables={nr_rows="1",nr_cols="3",
     hdr=[{width="15",alignment="-1",col_name="name",colhdr="Name"},
          {width="11",alignment="-1",col_name="initial",colhdr="Initial"},
          {width="11",alignment="-1",col_name="current",colhdr="Current"}],
     body=[variable={name="$trace_timestamp",initial="0"}
           variable={name="$foo",initial="10",current="15"}]}
     (gdb)

-trace-save
-----------

Synopsis
........

      -trace-save [ -r ] [ -ctf ] FILENAME

   Saves the collected trace data to FILENAME.  Without the '-r' option,
the data is downloaded from the target and saved in a local file.  With
the '-r' option the target is asked to perform the save.

   By default, this command will save the trace in the tfile format.
You can supply the optional '-ctf' argument to save it the CTF format.
See *note Trace Files:: for more information about CTF.

GDB Command
...........

The corresponding GDB command is 'tsave'.

-trace-start
------------

Synopsis
........

      -trace-start

   Starts a tracing experiment.  The result of this command does not
have any fields.

GDB Command
...........

The corresponding GDB command is 'tstart'.

-trace-status
-------------

Synopsis
........

      -trace-status

   Obtains the status of a tracing experiment.  The result may include
the following fields:

'supported'
     May have a value of either '0', when no tracing operations are
     supported, '1', when all tracing operations are supported, or
     'file' when examining trace file.  In the latter case, examining of
     trace frame is possible but new tracing experiement cannot be
     started.  This field is always present.

'running'
     May have a value of either '0' or '1' depending on whether tracing
     experiement is in progress on target.  This field is present if
     'supported' field is not '0'.

'stop-reason'
     Report the reason why the tracing was stopped last time.  This
     field may be absent iff tracing was never stopped on target yet.
     The value of 'request' means the tracing was stopped as result of
     the '-trace-stop' command.  The value of 'overflow' means the
     tracing buffer is full.  The value of 'disconnection' means tracing
     was automatically stopped when GDB has disconnected.  The value of
     'passcount' means tracing was stopped when a tracepoint was passed
     a maximal number of times for that tracepoint.  This field is
     present if 'supported' field is not '0'.

'stopping-tracepoint'
     The number of tracepoint whose passcount as exceeded.  This field
     is present iff the 'stop-reason' field has the value of
     'passcount'.

'frames'
'frames-created'
     The 'frames' field is a count of the total number of trace frames
     in the trace buffer, while 'frames-created' is the total created
     during the run, including ones that were discarded, such as when a
     circular trace buffer filled up.  Both fields are optional.

'buffer-size'
'buffer-free'
     These fields tell the current size of the tracing buffer and the
     remaining space.  These fields are optional.

'circular'
     The value of the circular trace buffer flag.  '1' means that the
     trace buffer is circular and old trace frames will be discarded if
     necessary to make room, '0' means that the trace buffer is linear
     and may fill up.

'disconnected'
     The value of the disconnected tracing flag.  '1' means that tracing
     will continue after GDB disconnects, '0' means that the trace run
     will stop.

'trace-file'
     The filename of the trace file being examined.  This field is
     optional, and only present when examining a trace file.

GDB Command
...........

The corresponding GDB command is 'tstatus'.

-trace-stop
-----------

Synopsis
........

      -trace-stop

   Stops a tracing experiment.  The result of this command has the same
fields as '-trace-status', except that the 'supported' and 'running'
fields are not output.

GDB Command
...........

The corresponding GDB command is 'tstop'.


File: gdb.info,  Node: GDB/MI Symbol Query,  Next: GDB/MI File Commands,  Prev: GDB/MI Tracepoint Commands,  Up: GDB/MI

27.18 GDB/MI Symbol Query Commands
==================================

The '-symbol-list-lines' Command
--------------------------------

Synopsis
........

      -symbol-list-lines FILENAME

   Print the list of lines that contain code and their associated
program addresses for the given source filename.  The entries are sorted
in ascending PC order.

GDB Command
...........

There is no corresponding GDB command.

Example
.......

     (gdb)
     -symbol-list-lines basics.c
     ^done,lines=[{pc="0x08048554",line="7"},{pc="0x0804855a",line="8"}]
     (gdb)


File: gdb.info,  Node: GDB/MI File Commands,  Next: GDB/MI Target Manipulation,  Prev: GDB/MI Symbol Query,  Up: GDB/MI

27.19 GDB/MI File Commands
==========================

This section describes the GDB/MI commands to specify executable file
names and to read in and obtain symbol table information.

The '-file-exec-and-symbols' Command
------------------------------------

Synopsis
........

      -file-exec-and-symbols FILE

   Specify the executable file to be debugged.  This file is the one
from which the symbol table is also read.  If no file is specified, the
command clears the executable and symbol information.  If breakpoints
are set when using this command with no arguments, GDB will produce
error messages.  Otherwise, no output is produced, except a completion
notification.

GDB Command
...........

The corresponding GDB command is 'file'.

Example
.......

     (gdb)
     -file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
     ^done
     (gdb)

The '-file-exec-file' Command
-----------------------------

Synopsis
........

      -file-exec-file FILE

   Specify the executable file to be debugged.  Unlike
'-file-exec-and-symbols', the symbol table is _not_ read from this file.
If used without argument, GDB clears the information about the
executable file.  No output is produced, except a completion
notification.

GDB Command
...........

The corresponding GDB command is 'exec-file'.

Example
.......

     (gdb)
     -file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
     ^done
     (gdb)

The '-file-list-exec-source-file' Command
-----------------------------------------

Synopsis
........

      -file-list-exec-source-file

   List the line number, the current source file, and the absolute path
to the current source file for the current executable.  The macro
information field has a value of '1' or '0' depending on whether or not
the file includes preprocessor macro information.

GDB Command
...........

The GDB equivalent is 'info source'

Example
.......

     (gdb)
     123-file-list-exec-source-file
     123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1"
     (gdb)

The '-file-list-exec-source-files' Command
------------------------------------------

Synopsis
........

      -file-list-exec-source-files

   List the source files for the current executable.

   It will always output both the filename and fullname (absolute file
name) of a source file.

GDB Command
...........

The GDB equivalent is 'info sources'.  'gdbtk' has an analogous command
'gdb_listfiles'.

Example
.......

     (gdb)
     -file-list-exec-source-files
     ^done,files=[
     {file=foo.c,fullname=/home/foo.c},
     {file=/home/bar.c,fullname=/home/bar.c},
     {file=gdb_could_not_find_fullpath.c}]
     (gdb)

The '-file-list-shared-libraries' Command
-----------------------------------------

Synopsis
........

      -file-list-shared-libraries [ REGEXP ]

   List the shared libraries in the program.  With a regular expression
REGEXP, only those libraries whose names match REGEXP are listed.

GDB Command
...........

The corresponding GDB command is 'info shared'.  The fields have a
similar meaning to the '=library-loaded' notification.  The 'ranges'
field specifies the multiple segments belonging to this library.  Each
range has the following fields:

'from'
     The address defining the inclusive lower bound of the segment.
'to'
     The address defining the exclusive upper bound of the segment.

Example
.......

     (gdb)
     -file-list-exec-source-files
     ^done,shared-libraries=[
     {id="/lib/libfoo.so",target-name="/lib/libfoo.so",host-name="/lib/libfoo.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x72815989",to="0x728162c0"}]},
     {id="/lib/libbar.so",target-name="/lib/libbar.so",host-name="/lib/libbar.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x76ee48c0",to="0x76ee9160"}]}]
     (gdb)

The '-file-symbol-file' Command
-------------------------------

Synopsis
........

      -file-symbol-file FILE

   Read symbol table info from the specified FILE argument.  When used
without arguments, clears GDB's symbol table info.  No output is
produced, except for a completion notification.

GDB Command
...........

The corresponding GDB command is 'symbol-file'.

Example
.......

     (gdb)
     -file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
     ^done
     (gdb)


File: gdb.info,  Node: GDB/MI Target Manipulation,  Next: GDB/MI File Transfer Commands,  Prev: GDB/MI File Commands,  Up: GDB/MI

27.20 GDB/MI Target Manipulation Commands
=========================================

The '-target-attach' Command
----------------------------

Synopsis
........

      -target-attach PID | GID | FILE

   Attach to a process PID or a file FILE outside of GDB, or a thread
group GID.  If attaching to a thread group, the id previously returned
by '-list-thread-groups --available' must be used.

GDB Command
...........

The corresponding GDB command is 'attach'.

Example
.......

     (gdb)
     -target-attach 34
     =thread-created,id="1"
     *stopped,thread-id="1",frame={addr="0xb7f7e410",func="bar",args=[]}
     ^done
     (gdb)

The '-target-detach' Command
----------------------------

Synopsis
........

      -target-detach [ PID | GID ]

   Detach from the remote target which normally resumes its execution.
If either PID or GID is specified, detaches from either the specified
process, or specified thread group.  There's no output.

GDB Command
...........

The corresponding GDB command is 'detach'.

Example
.......

     (gdb)
     -target-detach
     ^done
     (gdb)

The '-target-disconnect' Command
--------------------------------

Synopsis
........

      -target-disconnect

   Disconnect from the remote target.  There's no output and the target
is generally not resumed.

GDB Command
...........

The corresponding GDB command is 'disconnect'.

Example
.......

     (gdb)
     -target-disconnect
     ^done
     (gdb)

The '-target-download' Command
------------------------------

Synopsis
........

      -target-download

   Loads the executable onto the remote target.  It prints out an update
message every half second, which includes the fields:

'section'
     The name of the section.
'section-sent'
     The size of what has been sent so far for that section.
'section-size'
     The size of the section.
'total-sent'
     The total size of what was sent so far (the current and the
     previous sections).
'total-size'
     The size of the overall executable to download.

Each message is sent as status record (*note GDB/MI Output Syntax:
GDB/MI Output Syntax.).

   In addition, it prints the name and size of the sections, as they are
downloaded.  These messages include the following fields:

'section'
     The name of the section.
'section-size'
     The size of the section.
'total-size'
     The size of the overall executable to download.

At the end, a summary is printed.

GDB Command
...........

The corresponding GDB command is 'load'.

Example
.......

Note: each status message appears on a single line.  Here the messages
have been broken down so that they can fit onto a page.

     (gdb)
     -target-download
     +download,{section=".text",section-size="6668",total-size="9880"}
     +download,{section=".text",section-sent="512",section-size="6668",
     total-sent="512",total-size="9880"}
     +download,{section=".text",section-sent="1024",section-size="6668",
     total-sent="1024",total-size="9880"}
     +download,{section=".text",section-sent="1536",section-size="6668",
     total-sent="1536",total-size="9880"}
     +download,{section=".text",section-sent="2048",section-size="6668",
     total-sent="2048",total-size="9880"}
     +download,{section=".text",section-sent="2560",section-size="6668",
     total-sent="2560",total-size="9880"}
     +download,{section=".text",section-sent="3072",section-size="6668",
     total-sent="3072",total-size="9880"}
     +download,{section=".text",section-sent="3584",section-size="6668",
     total-sent="3584",total-size="9880"}
     +download,{section=".text",section-sent="4096",section-size="6668",
     total-sent="4096",total-size="9880"}
     +download,{section=".text",section-sent="4608",section-size="6668",
     total-sent="4608",total-size="9880"}
     +download,{section=".text",section-sent="5120",section-size="6668",
     total-sent="5120",total-size="9880"}
     +download,{section=".text",section-sent="5632",section-size="6668",
     total-sent="5632",total-size="9880"}
     +download,{section=".text",section-sent="6144",section-size="6668",
     total-sent="6144",total-size="9880"}
     +download,{section=".text",section-sent="6656",section-size="6668",
     total-sent="6656",total-size="9880"}
     +download,{section=".init",section-size="28",total-size="9880"}
     +download,{section=".fini",section-size="28",total-size="9880"}
     +download,{section=".data",section-size="3156",total-size="9880"}
     +download,{section=".data",section-sent="512",section-size="3156",
     total-sent="7236",total-size="9880"}
     +download,{section=".data",section-sent="1024",section-size="3156",
     total-sent="7748",total-size="9880"}
     +download,{section=".data",section-sent="1536",section-size="3156",
     total-sent="8260",total-size="9880"}
     +download,{section=".data",section-sent="2048",section-size="3156",
     total-sent="8772",total-size="9880"}
     +download,{section=".data",section-sent="2560",section-size="3156",
     total-sent="9284",total-size="9880"}
     +download,{section=".data",section-sent="3072",section-size="3156",
     total-sent="9796",total-size="9880"}
     ^done,address="0x10004",load-size="9880",transfer-rate="6586",
     write-rate="429"
     (gdb)

GDB Command
...........

No equivalent.

Example
.......

N.A.

The '-target-flash-erase' Command
---------------------------------

Synopsis
........

      -target-flash-erase

   Erases all known flash memory regions on the target.

   The corresponding GDB command is 'flash-erase'.

   The output is a list of flash regions that have been erased, with
starting addresses and memory region sizes.

     (gdb)
     -target-flash-erase
     ^done,erased-regions={address="0x0",size="0x40000"}
     (gdb)

The '-target-select' Command
----------------------------

Synopsis
........

      -target-select TYPE PARAMETERS ...

   Connect GDB to the remote target.  This command takes two args:

'TYPE'
     The type of target, for instance 'remote', etc.
'PARAMETERS'
     Device names, host names and the like.  *Note Commands for Managing
     Targets: Target Commands, for more details.

   The output is a connection notification, followed by the address at
which the target program is, in the following form:

     ^connected,addr="ADDRESS",func="FUNCTION NAME",
       args=[ARG LIST]

GDB Command
...........

The corresponding GDB command is 'target'.

Example
.......

     (gdb)
     -target-select remote /dev/ttya
     ^connected,addr="0xfe00a300",func="??",args=[]
     (gdb)


File: gdb.info,  Node: GDB/MI File Transfer Commands,  Next: GDB/MI Ada Exceptions Commands,  Prev: GDB/MI Target Manipulation,  Up: GDB/MI

27.21 GDB/MI File Transfer Commands
===================================

The '-target-file-put' Command
------------------------------

Synopsis
........

      -target-file-put HOSTFILE TARGETFILE

   Copy file HOSTFILE from the host system (the machine running GDB) to
TARGETFILE on the target system.

GDB Command
...........

The corresponding GDB command is 'remote put'.

Example
.......

     (gdb)
     -target-file-put localfile remotefile
     ^done
     (gdb)

The '-target-file-get' Command
------------------------------

Synopsis
........

      -target-file-get TARGETFILE HOSTFILE

   Copy file TARGETFILE from the target system to HOSTFILE on the host
system.

GDB Command
...........

The corresponding GDB command is 'remote get'.

Example
.......

     (gdb)
     -target-file-get remotefile localfile
     ^done
     (gdb)

The '-target-file-delete' Command
---------------------------------

Synopsis
........

      -target-file-delete TARGETFILE

   Delete TARGETFILE from the target system.

GDB Command
...........

The corresponding GDB command is 'remote delete'.

Example
.......

     (gdb)
     -target-file-delete remotefile
     ^done
     (gdb)


File: gdb.info,  Node: GDB/MI Ada Exceptions Commands,  Next: GDB/MI Support Commands,  Prev: GDB/MI File Transfer Commands,  Up: GDB/MI

27.22 Ada Exceptions GDB/MI Commands
====================================

The '-info-ada-exceptions' Command
----------------------------------

Synopsis
........

      -info-ada-exceptions [ REGEXP]

   List all Ada exceptions defined within the program being debugged.
With a regular expression REGEXP, only those exceptions whose names
match REGEXP are listed.

GDB Command
...........

The corresponding GDB command is 'info exceptions'.

Result
......

The result is a table of Ada exceptions.  The following columns are
defined for each exception:

'name'
     The name of the exception.

'address'
     The address of the exception.

Example
.......

     -info-ada-exceptions aint
     ^done,ada-exceptions={nr_rows="2",nr_cols="2",
     hdr=[{width="1",alignment="-1",col_name="name",colhdr="Name"},
     {width="1",alignment="-1",col_name="address",colhdr="Address"}],
     body=[{name="constraint_error",address="0x0000000000613da0"},
     {name="const.aint_global_e",address="0x0000000000613b00"}]}

Catching Ada Exceptions
-----------------------

The commands describing how to ask GDB to stop when a program raises an
exception are described at *note Ada Exception GDB/MI Catchpoint
Commands::.


File: gdb.info,  Node: GDB/MI Support Commands,  Next: GDB/MI Miscellaneous Commands,  Prev: GDB/MI Ada Exceptions Commands,  Up: GDB/MI

27.23 GDB/MI Support Commands
=============================

Since new commands and features get regularly added to GDB/MI, some
commands are available to help front-ends query the debugger about
support for these capabilities.  Similarly, it is also possible to query
GDB about target support of certain features.

The '-info-gdb-mi-command' Command
----------------------------------

Synopsis
........

      -info-gdb-mi-command CMD_NAME

   Query support for the GDB/MI command named CMD_NAME.

   Note that the dash ('-') starting all GDB/MI commands is technically
not part of the command name (*note GDB/MI Input Syntax::), and thus
should be omitted in CMD_NAME.  However, for ease of use, this command
also accepts the form with the leading dash.

GDB Command
...........

There is no corresponding GDB command.

Result
......

The result is a tuple.  There is currently only one field:

'exists'
     This field is equal to '"true"' if the GDB/MI command exists,
     '"false"' otherwise.

Example
.......

Here is an example where the GDB/MI command does not exist:

     -info-gdb-mi-command unsupported-command
     ^done,command={exists="false"}

And here is an example where the GDB/MI command is known to the
debugger:

     -info-gdb-mi-command symbol-list-lines
     ^done,command={exists="true"}

The '-list-features' Command
----------------------------

Returns a list of particular features of the MI protocol that this
version of gdb implements.  A feature can be a command, or a new field
in an output of some command, or even an important bugfix.  While a
frontend can sometimes detect presence of a feature at runtime, it is
easier to perform detection at debugger startup.

   The command returns a list of strings, with each string naming an
available feature.  Each returned string is just a name, it does not
have any internal structure.  The list of possible feature names is
given below.

   Example output:

     (gdb) -list-features
     ^done,result=["feature1","feature2"]

   The current list of features is:

'frozen-varobjs'
     Indicates support for the '-var-set-frozen' command, as well as
     possible presense of the 'frozen' field in the output of
     '-varobj-create'.
'pending-breakpoints'
     Indicates support for the '-f' option to the '-break-insert'
     command.
'python'
     Indicates Python scripting support, Python-based pretty-printing
     commands, and possible presence of the 'display_hint' field in the
     output of '-var-list-children'
'thread-info'
     Indicates support for the '-thread-info' command.
'data-read-memory-bytes'
     Indicates support for the '-data-read-memory-bytes' and the
     '-data-write-memory-bytes' commands.
'breakpoint-notifications'
     Indicates that changes to breakpoints and breakpoints created via
     the CLI will be announced via async records.
'ada-task-info'
     Indicates support for the '-ada-task-info' command.
'language-option'
     Indicates that all GDB/MI commands accept the '--language' option
     (*note Context management::).
'info-gdb-mi-command'
     Indicates support for the '-info-gdb-mi-command' command.
'undefined-command-error-code'
     Indicates support for the "undefined-command" error code in error
     result records, produced when trying to execute an undefined GDB/MI
     command (*note GDB/MI Result Records::).
'exec-run-start-option'
     Indicates that the '-exec-run' command supports the '--start'
     option (*note GDB/MI Program Execution::).

The '-list-target-features' Command
-----------------------------------

Returns a list of particular features that are supported by the target.
Those features affect the permitted MI commands, but unlike the features
reported by the '-list-features' command, the features depend on which
target GDB is using at the moment.  Whenever a target can change, due to
commands such as '-target-select', '-target-attach' or '-exec-run', the
list of target features may change, and the frontend should obtain it
again.  Example output:

     (gdb) -list-target-features
     ^done,result=["async"]

   The current list of features is:

'async'
     Indicates that the target is capable of asynchronous command
     execution, which means that GDB will accept further commands while
     the target is running.

'reverse'
     Indicates that the target is capable of reverse execution.  *Note
     Reverse Execution::, for more information.


File: gdb.info,  Node: GDB/MI Miscellaneous Commands,  Prev: GDB/MI Support Commands,  Up: GDB/MI

27.24 Miscellaneous GDB/MI Commands
===================================

The '-gdb-exit' Command
-----------------------

Synopsis
........

      -gdb-exit

   Exit GDB immediately.

GDB Command
...........

Approximately corresponds to 'quit'.

Example
.......

     (gdb)
     -gdb-exit
     ^exit

The '-gdb-set' Command
----------------------

Synopsis
........

      -gdb-set

   Set an internal GDB variable.

GDB Command
...........

The corresponding GDB command is 'set'.

Example
.......

     (gdb)
     -gdb-set $foo=3
     ^done
     (gdb)

The '-gdb-show' Command
-----------------------

Synopsis
........

      -gdb-show

   Show the current value of a GDB variable.

GDB Command
...........

The corresponding GDB command is 'show'.

Example
.......

     (gdb)
     -gdb-show annotate
     ^done,value="0"
     (gdb)

The '-gdb-version' Command
--------------------------

Synopsis
........

      -gdb-version

   Show version information for GDB.  Used mostly in testing.

GDB Command
...........

The GDB equivalent is 'show version'.  GDB by default shows this
information when you start an interactive session.

Example
.......

     (gdb)
     -gdb-version
     ~GNU gdb 5.2.1
     ~Copyright 2000 Free Software Foundation, Inc.
     ~GDB is free software, covered by the GNU General Public License, and
     ~you are welcome to change it and/or distribute copies of it under
     ~ certain conditions.
     ~Type "show copying" to see the conditions.
     ~There is absolutely no warranty for GDB.  Type "show warranty" for
     ~ details.
     ~This GDB was configured as
      "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
     ^done
     (gdb)

The '-list-thread-groups' Command
---------------------------------

Synopsis
--------

     -list-thread-groups [ --available ] [ --recurse 1 ] [ GROUP ... ]

   Lists thread groups (*note Thread groups::).  When a single thread
group is passed as the argument, lists the children of that group.  When
several thread group are passed, lists information about those thread
groups.  Without any parameters, lists information about all top-level
thread groups.

   Normally, thread groups that are being debugged are reported.  With
the '--available' option, GDB reports thread groups available on the
target.

   The output of this command may have either a 'threads' result or a
'groups' result.  The 'thread' result has a list of tuples as value,
with each tuple describing a thread (*note GDB/MI Thread Information::).
The 'groups' result has a list of tuples as value, each tuple describing
a thread group.  If top-level groups are requested (that is, no
parameter is passed), or when several groups are passed, the output
always has a 'groups' result.  The format of the 'group' result is
described below.

   To reduce the number of roundtrips it's possible to list thread
groups together with their children, by passing the '--recurse' option
and the recursion depth.  Presently, only recursion depth of 1 is
permitted.  If this option is present, then every reported thread group
will also include its children, either as 'group' or 'threads' field.

   In general, any combination of option and parameters is permitted,
with the following caveats:

   * When a single thread group is passed, the output will typically be
     the 'threads' result.  Because threads may not contain anything,
     the 'recurse' option will be ignored.

   * When the '--available' option is passed, limited information may be
     available.  In particular, the list of threads of a process might
     be inaccessible.  Further, specifying specific thread groups might
     not give any performance advantage over listing all thread groups.
     The frontend should assume that '-list-thread-groups --available'
     is always an expensive operation and cache the results.

   The 'groups' result is a list of tuples, where each tuple may have
the following fields:

'id'
     Identifier of the thread group.  This field is always present.  The
     identifier is an opaque string; frontends should not try to convert
     it to an integer, even though it might look like one.

'type'
     The type of the thread group.  At present, only 'process' is a
     valid type.

'pid'
     The target-specific process identifier.  This field is only present
     for thread groups of type 'process' and only if the process exists.

'exit-code'
     The exit code of this group's last exited thread, formatted in
     octal.  This field is only present for thread groups of type
     'process' and only if the process is not running.

'num_children'
     The number of children this thread group has.  This field may be
     absent for an available thread group.

'threads'
     This field has a list of tuples as value, each tuple describing a
     thread.  It may be present if the '--recurse' option is specified,
     and it's actually possible to obtain the threads.

'cores'
     This field is a list of integers, each identifying a core that one
     thread of the group is running on.  This field may be absent if
     such information is not available.

'executable'
     The name of the executable file that corresponds to this thread
     group.  The field is only present for thread groups of type
     'process', and only if there is a corresponding executable file.

Example
-------

     gdb
     -list-thread-groups
     ^done,groups=[{id="17",type="process",pid="yyy",num_children="2"}]
     -list-thread-groups 17
     ^done,threads=[{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
        frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]},state="running"},
     {id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
        frame={level="0",addr="0x0804891f",func="foo",args=[{name="i",value="10"}],
                file="/tmp/a.c",fullname="/tmp/a.c",line="158"},state="running"}]]
     -list-thread-groups --available
     ^done,groups=[{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]}]
     -list-thread-groups --available --recurse 1
      ^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
                     threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
                              {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},..]
     -list-thread-groups --available --recurse 1 17 18
     ^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
                    threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
                             {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},...]

The '-info-os' Command
----------------------

Synopsis
........

     -info-os [ TYPE ]

   If no argument is supplied, the command returns a table of available
operating-system-specific information types.  If one of these types is
supplied as an argument TYPE, then the command returns a table of data
of that type.

   The types of information available depend on the target operating
system.

GDB Command
...........

The corresponding GDB command is 'info os'.

Example
.......

When run on a GNU/Linux system, the output will look something like
this:

     gdb
     -info-os
     ^done,OSDataTable={nr_rows="10",nr_cols="3",
     hdr=[{width="10",alignment="-1",col_name="col0",colhdr="Type"},
          {width="10",alignment="-1",col_name="col1",colhdr="Description"},
          {width="10",alignment="-1",col_name="col2",colhdr="Title"}],
     body=[item={col0="cpus",col1="Listing of all cpus/cores on the system",
                 col2="CPUs"},
           item={col0="files",col1="Listing of all file descriptors",
                 col2="File descriptors"},
           item={col0="modules",col1="Listing of all loaded kernel modules",
                 col2="Kernel modules"},
           item={col0="msg",col1="Listing of all message queues",
                 col2="Message queues"},
           item={col0="processes",col1="Listing of all processes",
                 col2="Processes"},
           item={col0="procgroups",col1="Listing of all process groups",
                 col2="Process groups"},
           item={col0="semaphores",col1="Listing of all semaphores",
                 col2="Semaphores"},
           item={col0="shm",col1="Listing of all shared-memory regions",
                 col2="Shared-memory regions"},
           item={col0="sockets",col1="Listing of all internet-domain sockets",
                 col2="Sockets"},
           item={col0="threads",col1="Listing of all threads",
                 col2="Threads"}]
     gdb
     -info-os processes
     ^done,OSDataTable={nr_rows="190",nr_cols="4",
     hdr=[{width="10",alignment="-1",col_name="col0",colhdr="pid"},
          {width="10",alignment="-1",col_name="col1",colhdr="user"},
          {width="10",alignment="-1",col_name="col2",colhdr="command"},
          {width="10",alignment="-1",col_name="col3",colhdr="cores"}],
     body=[item={col0="1",col1="root",col2="/sbin/init",col3="0"},
           item={col0="2",col1="root",col2="[kthreadd]",col3="1"},
           item={col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"},
           ...
           item={col0="26446",col1="stan",col2="bash",col3="0"},
           item={col0="28152",col1="stan",col2="bash",col3="1"}]}
     (gdb)

   (Note that the MI output here includes a '"Title"' column that does
not appear in command-line 'info os'; this column is useful for MI
clients that want to enumerate the types of data, such as in a popup
menu, but is needless clutter on the command line, and 'info os' omits
it.)

The '-add-inferior' Command
---------------------------

Synopsis
--------

     -add-inferior

   Creates a new inferior (*note Inferiors and Programs::).  The created
inferior is not associated with any executable.  Such association may be
established with the '-file-exec-and-symbols' command (*note GDB/MI File
Commands::).  The command response has a single field, 'inferior', whose
value is the identifier of the thread group corresponding to the new
inferior.

Example
-------

     gdb
     -add-inferior
     ^done,inferior="i3"

The '-interpreter-exec' Command
-------------------------------

Synopsis
--------

     -interpreter-exec INTERPRETER COMMAND

   Execute the specified COMMAND in the given INTERPRETER.

GDB Command
-----------

The corresponding GDB command is 'interpreter-exec'.

Example
-------

     (gdb)
     -interpreter-exec console "break main"
     &"During symbol reading, couldn't parse type; debugger out of date?.\n"
     &"During symbol reading, bad structure-type format.\n"
     ~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
     ^done
     (gdb)

The '-inferior-tty-set' Command
-------------------------------

Synopsis
--------

     -inferior-tty-set /dev/pts/1

   Set terminal for future runs of the program being debugged.

GDB Command
-----------

The corresponding GDB command is 'set inferior-tty' /dev/pts/1.

Example
-------

     (gdb)
     -inferior-tty-set /dev/pts/1
     ^done
     (gdb)

The '-inferior-tty-show' Command
--------------------------------

Synopsis
--------

     -inferior-tty-show

   Show terminal for future runs of program being debugged.

GDB Command
-----------

The corresponding GDB command is 'show inferior-tty'.

Example
-------

     (gdb)
     -inferior-tty-set /dev/pts/1
     ^done
     (gdb)
     -inferior-tty-show
     ^done,inferior_tty_terminal="/dev/pts/1"
     (gdb)

The '-enable-timings' Command
-----------------------------

Synopsis
--------

     -enable-timings [yes | no]

   Toggle the printing of the wallclock, user and system times for an MI
command as a field in its output.  This command is to help frontend
developers optimize the performance of their code.  No argument is
equivalent to 'yes'.

GDB Command
-----------

No equivalent.

Example
-------

     (gdb)
     -enable-timings
     ^done
     (gdb)
     -break-insert main
     ^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
     addr="0x080484ed",func="main",file="myprog.c",
     fullname="/home/nickrob/myprog.c",line="73",thread-groups=["i1"],
     times="0"},
     time={wallclock="0.05185",user="0.00800",system="0.00000"}
     (gdb)
     -enable-timings no
     ^done
     (gdb)
     -exec-run
     ^running
     (gdb)
     *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
     frame={addr="0x080484ed",func="main",args=[{name="argc",value="1"},
     {name="argv",value="0xbfb60364"}],file="myprog.c",
     fullname="/home/nickrob/myprog.c",line="73"}
     (gdb)


File: gdb.info,  Node: Annotations,  Next: JIT Interface,  Prev: GDB/MI,  Up: Top

28 GDB Annotations
******************

This chapter describes annotations in GDB.  Annotations were designed to
interface GDB to graphical user interfaces or other similar programs
which want to interact with GDB at a relatively high level.

   The annotation mechanism has largely been superseded by GDB/MI (*note
GDB/MI::).

* Menu:

* Annotations Overview::  What annotations are; the general syntax.
* Server Prefix::       Issuing a command without affecting user state.
* Prompting::           Annotations marking GDB's need for input.
* Errors::              Annotations for error messages.
* Invalidation::        Some annotations describe things now invalid.
* Annotations for Running::
                        Whether the program is running, how it stopped, etc.
* Source Annotations::  Annotations describing source code.


File: gdb.info,  Node: Annotations Overview,  Next: Server Prefix,  Up: Annotations

28.1 What is an Annotation?
===========================

Annotations start with a newline character, two 'control-z' characters,
and the name of the annotation.  If there is no additional information
associated with this annotation, the name of the annotation is followed
immediately by a newline.  If there is additional information, the name
of the annotation is followed by a space, the additional information,
and a newline.  The additional information cannot contain newline
characters.

   Any output not beginning with a newline and two 'control-z'
characters denotes literal output from GDB.  Currently there is no need
for GDB to output a newline followed by two 'control-z' characters, but
if there was such a need, the annotations could be extended with an
'escape' annotation which means those three characters as output.

   The annotation LEVEL, which is specified using the '--annotate'
command line option (*note Mode Options::), controls how much
information GDB prints together with its prompt, values of expressions,
source lines, and other types of output.  Level 0 is for no annotations,
level 1 is for use when GDB is run as a subprocess of GNU Emacs, level 3
is the maximum annotation suitable for programs that control GDB, and
level 2 annotations have been made obsolete (*note Limitations of the
Annotation Interface: (annotate)Limitations.).

'set annotate LEVEL'
     The GDB command 'set annotate' sets the level of annotations to the
     specified LEVEL.

'show annotate'
     Show the current annotation level.

   This chapter describes level 3 annotations.

   A simple example of starting up GDB with annotations is:

     $ gdb --annotate=3
     GNU gdb 6.0
     Copyright 2003 Free Software Foundation, Inc.
     GDB is free software, covered by the GNU General Public License,
     and you are welcome to change it and/or distribute copies of it
     under certain conditions.
     Type "show copying" to see the conditions.
     There is absolutely no warranty for GDB.  Type "show warranty"
     for details.
     This GDB was configured as "i386-pc-linux-gnu"

     ^Z^Zpre-prompt
     (gdb)
     ^Z^Zprompt
     quit

     ^Z^Zpost-prompt
     $

   Here 'quit' is input to GDB; the rest is output from GDB.  The three
lines beginning '^Z^Z' (where '^Z' denotes a 'control-z' character) are
annotations; the rest is output from GDB.


File: gdb.info,  Node: Server Prefix,  Next: Prompting,  Prev: Annotations Overview,  Up: Annotations

28.2 The Server Prefix
======================

If you prefix a command with 'server ' then it will not affect the
command history, nor will it affect GDB's notion of which command to
repeat if <RET> is pressed on a line by itself.  This means that
commands can be run behind a user's back by a front-end in a transparent
manner.

   The 'server ' prefix does not affect the recording of values into the
value history; to print a value without recording it into the value
history, use the 'output' command instead of the 'print' command.

   Using this prefix also disables confirmation requests (*note
confirmation requests::).


File: gdb.info,  Node: Prompting,  Next: Errors,  Prev: Server Prefix,  Up: Annotations

28.3 Annotation for GDB Input
=============================

When GDB prompts for input, it annotates this fact so it is possible to
know when to send output, when the output from a given command is over,
etc.

   Different kinds of input each have a different "input type".  Each
input type has three annotations: a 'pre-' annotation, which denotes the
beginning of any prompt which is being output, a plain annotation, which
denotes the end of the prompt, and then a 'post-' annotation which
denotes the end of any echo which may (or may not) be associated with
the input.  For example, the 'prompt' input type features the following
annotations:

     ^Z^Zpre-prompt
     ^Z^Zprompt
     ^Z^Zpost-prompt

   The input types are

'prompt'
     When GDB is prompting for a command (the main GDB prompt).

'commands'
     When GDB prompts for a set of commands, like in the 'commands'
     command.  The annotations are repeated for each command which is
     input.

'overload-choice'
     When GDB wants the user to select between various overloaded
     functions.

'query'
     When GDB wants the user to confirm a potentially dangerous
     operation.

'prompt-for-continue'
     When GDB is asking the user to press return to continue.  Note:
     Don't expect this to work well; instead use 'set height 0' to
     disable prompting.  This is because the counting of lines is buggy
     in the presence of annotations.


File: gdb.info,  Node: Errors,  Next: Invalidation,  Prev: Prompting,  Up: Annotations

28.4 Errors
===========

     ^Z^Zquit

   This annotation occurs right before GDB responds to an interrupt.

     ^Z^Zerror

   This annotation occurs right before GDB responds to an error.

   Quit and error annotations indicate that any annotations which GDB
was in the middle of may end abruptly.  For example, if a
'value-history-begin' annotation is followed by a 'error', one cannot
expect to receive the matching 'value-history-end'.  One cannot expect
not to receive it either, however; an error annotation does not
necessarily mean that GDB is immediately returning all the way to the
top level.

   A quit or error annotation may be preceded by

     ^Z^Zerror-begin

   Any output between that and the quit or error annotation is the error
message.

   Warning messages are not yet annotated.


File: gdb.info,  Node: Invalidation,  Next: Annotations for Running,  Prev: Errors,  Up: Annotations

28.5 Invalidation Notices
=========================

The following annotations say that certain pieces of state may have
changed.

'^Z^Zframes-invalid'

     The frames (for example, output from the 'backtrace' command) may
     have changed.

'^Z^Zbreakpoints-invalid'

     The breakpoints may have changed.  For example, the user just added
     or deleted a breakpoint.


File: gdb.info,  Node: Annotations for Running,  Next: Source Annotations,  Prev: Invalidation,  Up: Annotations

28.6 Running the Program
========================

When the program starts executing due to a GDB command such as 'step' or
'continue',

     ^Z^Zstarting

   is output.  When the program stops,

     ^Z^Zstopped

   is output.  Before the 'stopped' annotation, a variety of annotations
describe how the program stopped.

'^Z^Zexited EXIT-STATUS'
     The program exited, and EXIT-STATUS is the exit status (zero for
     successful exit, otherwise nonzero).

'^Z^Zsignalled'
     The program exited with a signal.  After the '^Z^Zsignalled', the
     annotation continues:

          INTRO-TEXT
          ^Z^Zsignal-name
          NAME
          ^Z^Zsignal-name-end
          MIDDLE-TEXT
          ^Z^Zsignal-string
          STRING
          ^Z^Zsignal-string-end
          END-TEXT

     where NAME is the name of the signal, such as 'SIGILL' or
     'SIGSEGV', and STRING is the explanation of the signal, such as
     'Illegal Instruction' or 'Segmentation fault'.  The arguments
     INTRO-TEXT, MIDDLE-TEXT, and END-TEXT are for the user's benefit
     and have no particular format.

'^Z^Zsignal'
     The syntax of this annotation is just like 'signalled', but GDB is
     just saying that the program received the signal, not that it was
     terminated with it.

'^Z^Zbreakpoint NUMBER'
     The program hit breakpoint number NUMBER.

'^Z^Zwatchpoint NUMBER'
     The program hit watchpoint number NUMBER.


File: gdb.info,  Node: Source Annotations,  Prev: Annotations for Running,  Up: Annotations

28.7 Displaying Source
======================

The following annotation is used instead of displaying source code:

     ^Z^Zsource FILENAME:LINE:CHARACTER:MIDDLE:ADDR

   where FILENAME is an absolute file name indicating which source file,
LINE is the line number within that file (where 1 is the first line in
the file), CHARACTER is the character position within the file (where 0
is the first character in the file) (for most debug formats this will
necessarily point to the beginning of a line), MIDDLE is 'middle' if
ADDR is in the middle of the line, or 'beg' if ADDR is at the beginning
of the line, and ADDR is the address in the target program associated
with the source which is being displayed.  The ADDR is in the form '0x'
followed by one or more lowercase hex digits (note that this does not
depend on the language).


File: gdb.info,  Node: JIT Interface,  Next: In-Process Agent,  Prev: Annotations,  Up: Top

29 JIT Compilation Interface
****************************

This chapter documents GDB's "just-in-time" (JIT) compilation interface.
A JIT compiler is a program or library that generates native executable
code at runtime and executes it, usually in order to achieve good
performance while maintaining platform independence.

   Programs that use JIT compilation are normally difficult to debug
because portions of their code are generated at runtime, instead of
being loaded from object files, which is where GDB normally finds the
program's symbols and debug information.  In order to debug programs
that use JIT compilation, GDB has an interface that allows the program
to register in-memory symbol files with GDB at runtime.

   If you are using GDB to debug a program that uses this interface,
then it should work transparently so long as you have not stripped the
binary.  If you are developing a JIT compiler, then the interface is
documented in the rest of this chapter.  At this time, the only known
client of this interface is the LLVM JIT.

   Broadly speaking, the JIT interface mirrors the dynamic loader
interface.  The JIT compiler communicates with GDB by writing data into
a global variable and calling a fuction at a well-known symbol.  When
GDB attaches, it reads a linked list of symbol files from the global
variable to find existing code, and puts a breakpoint in the function so
that it can find out about additional code.

* Menu:

* Declarations::                Relevant C struct declarations
* Registering Code::            Steps to register code
* Unregistering Code::          Steps to unregister code
* Custom Debug Info::           Emit debug information in a custom format


File: gdb.info,  Node: Declarations,  Next: Registering Code,  Up: JIT Interface

29.1 JIT Declarations
=====================

These are the relevant struct declarations that a C program should
include to implement the interface:

     typedef enum
     {
       JIT_NOACTION = 0,
       JIT_REGISTER_FN,
       JIT_UNREGISTER_FN
     } jit_actions_t;

     struct jit_code_entry
     {
       struct jit_code_entry *next_entry;
       struct jit_code_entry *prev_entry;
       const char *symfile_addr;
       uint64_t symfile_size;
     };

     struct jit_descriptor
     {
       uint32_t version;
       /* This type should be jit_actions_t, but we use uint32_t
          to be explicit about the bitwidth.  */
       uint32_t action_flag;
       struct jit_code_entry *relevant_entry;
       struct jit_code_entry *first_entry;
     };

     /* GDB puts a breakpoint in this function.  */
     void __attribute__((noinline)) __jit_debug_register_code() { };

     /* Make sure to specify the version statically, because the
        debugger may check the version before we can set it.  */
     struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };

   If the JIT is multi-threaded, then it is important that the JIT
synchronize any modifications to this global data properly, which can
easily be done by putting a global mutex around modifications to these
structures.


File: gdb.info,  Node: Registering Code,  Next: Unregistering Code,  Prev: Declarations,  Up: JIT Interface

29.2 Registering Code
=====================

To register code with GDB, the JIT should follow this protocol:

   * Generate an object file in memory with symbols and other desired
     debug information.  The file must include the virtual addresses of
     the sections.

   * Create a code entry for the file, which gives the start and size of
     the symbol file.

   * Add it to the linked list in the JIT descriptor.

   * Point the relevant_entry field of the descriptor at the entry.

   * Set 'action_flag' to 'JIT_REGISTER' and call
     '__jit_debug_register_code'.

   When GDB is attached and the breakpoint fires, GDB uses the
'relevant_entry' pointer so it doesn't have to walk the list looking for
new code.  However, the linked list must still be maintained in order to
allow GDB to attach to a running process and still find the symbol
files.


File: gdb.info,  Node: Unregistering Code,  Next: Custom Debug Info,  Prev: Registering Code,  Up: JIT Interface

29.3 Unregistering Code
=======================

If code is freed, then the JIT should use the following protocol:

   * Remove the code entry corresponding to the code from the linked
     list.

   * Point the 'relevant_entry' field of the descriptor at the code
     entry.

   * Set 'action_flag' to 'JIT_UNREGISTER' and call
     '__jit_debug_register_code'.

   If the JIT frees or recompiles code without unregistering it, then
GDB and the JIT will leak the memory used for the associated symbol
files.


File: gdb.info,  Node: Custom Debug Info,  Prev: Unregistering Code,  Up: JIT Interface

29.4 Custom Debug Info
======================

Generating debug information in platform-native file formats (like ELF
or COFF) may be an overkill for JIT compilers; especially if all the
debug info is used for is displaying a meaningful backtrace.  The issue
can be resolved by having the JIT writers decide on a debug info format
and also provide a reader that parses the debug info generated by the
JIT compiler.  This section gives a brief overview on writing such a
parser.  More specific details can be found in the source file
'gdb/jit-reader.in', which is also installed as a header at
'INCLUDEDIR/gdb/jit-reader.h' for easy inclusion.

   The reader is implemented as a shared object (so this functionality
is not available on platforms which don't allow loading shared objects
at runtime).  Two GDB commands, 'jit-reader-load' and
'jit-reader-unload' are provided, to be used to load and unload the
readers from a preconfigured directory.  Once loaded, the shared object
is used the parse the debug information emitted by the JIT compiler.

* Menu:

* Using JIT Debug Info Readers::       How to use supplied readers correctly
* Writing JIT Debug Info Readers::     Creating a debug-info reader


File: gdb.info,  Node: Using JIT Debug Info Readers,  Next: Writing JIT Debug Info Readers,  Up: Custom Debug Info

29.4.1 Using JIT Debug Info Readers
-----------------------------------

Readers can be loaded and unloaded using the 'jit-reader-load' and
'jit-reader-unload' commands.

'jit-reader-load READER'
     Load the JIT reader named READER, which is a shared object
     specified as either an absolute or a relative file name.  In the
     latter case, GDB will try to load the reader from a pre-configured
     directory, usually 'LIBDIR/gdb/' on a UNIX system (here LIBDIR is
     the system library directory, often '/usr/local/lib').

     Only one reader can be active at a time; trying to load a second
     reader when one is already loaded will result in GDB reporting an
     error.  A new JIT reader can be loaded by first unloading the
     current one using 'jit-reader-unload' and then invoking
     'jit-reader-load'.

'jit-reader-unload'
     Unload the currently loaded JIT reader.


File: gdb.info,  Node: Writing JIT Debug Info Readers,  Prev: Using JIT Debug Info Readers,  Up: Custom Debug Info

29.4.2 Writing JIT Debug Info Readers
-------------------------------------

As mentioned, a reader is essentially a shared object conforming to a
certain ABI. This ABI is described in 'jit-reader.h'.

   'jit-reader.h' defines the structures, macros and functions required
to write a reader.  It is installed (along with GDB), in
'INCLUDEDIR/gdb' where INCLUDEDIR is the system include directory.

   Readers need to be released under a GPL compatible license.  A reader
can be declared as released under such a license by placing the macro
'GDB_DECLARE_GPL_COMPATIBLE_READER' in a source file.

   The entry point for readers is the symbol 'gdb_init_reader', which is
expected to be a function with the prototype

     extern struct gdb_reader_funcs *gdb_init_reader (void);

   'struct gdb_reader_funcs' contains a set of pointers to callback
functions.  These functions are executed to read the debug info
generated by the JIT compiler ('read'), to unwind stack frames
('unwind') and to create canonical frame IDs ('get_Frame_id').  It also
has a callback that is called when the reader is being unloaded
('destroy').  The struct looks like this

     struct gdb_reader_funcs
     {
       /* Must be set to GDB_READER_INTERFACE_VERSION.  */
       int reader_version;

       /* For use by the reader.  */
       void *priv_data;

       gdb_read_debug_info *read;
       gdb_unwind_frame *unwind;
       gdb_get_frame_id *get_frame_id;
       gdb_destroy_reader *destroy;
     };

   The callbacks are provided with another set of callbacks by GDB to do
their job.  For 'read', these callbacks are passed in a 'struct
gdb_symbol_callbacks' and for 'unwind' and 'get_frame_id', in a 'struct
gdb_unwind_callbacks'.  'struct gdb_symbol_callbacks' has callbacks to
create new object files and new symbol tables inside those object files.
'struct gdb_unwind_callbacks' has callbacks to read registers off the
current frame and to write out the values of the registers in the
previous frame.  Both have a callback ('target_read') to read bytes off
the target's address space.


File: gdb.info,  Node: In-Process Agent,  Next: GDB Bugs,  Prev: JIT Interface,  Up: Top

30 In-Process Agent
*******************

The traditional debugging model is conceptually low-speed, but works
fine, because most bugs can be reproduced in debugging-mode execution.
However, as multi-core or many-core processors are becoming mainstream,
and multi-threaded programs become more and more popular, there should
be more and more bugs that only manifest themselves at normal-mode
execution, for example, thread races, because debugger's interference
with the program's timing may conceal the bugs.  On the other hand, in
some applications, it is not feasible for the debugger to interrupt the
program's execution long enough for the developer to learn anything
helpful about its behavior.  If the program's correctness depends on its
real-time behavior, delays introduced by a debugger might cause the
program to fail, even when the code itself is correct.  It is useful to
be able to observe the program's behavior without interrupting it.

   Therefore, traditional debugging model is too intrusive to reproduce
some bugs.  In order to reduce the interference with the program, we can
reduce the number of operations performed by debugger.  The "In-Process
Agent", a shared library, is running within the same process with
inferior, and is able to perform some debugging operations itself.  As a
result, debugger is only involved when necessary, and performance of
debugging can be improved accordingly.  Note that interference with
program can be reduced but can't be removed completely, because the
in-process agent will still stop or slow down the program.

   The in-process agent can interpret and execute Agent Expressions
(*note Agent Expressions::) during performing debugging operations.  The
agent expressions can be used for different purposes, such as collecting
data in tracepoints, and condition evaluation in breakpoints.

   You can control whether the in-process agent is used as an aid for
debugging with the following commands:

'set agent on'
     Causes the in-process agent to perform some operations on behalf of
     the debugger.  Just which operations requested by the user will be
     done by the in-process agent depends on the its capabilities.  For
     example, if you request to evaluate breakpoint conditions in the
     in-process agent, and the in-process agent has such capability as
     well, then breakpoint conditions will be evaluated in the
     in-process agent.

'set agent off'
     Disables execution of debugging operations by the in-process agent.
     All of the operations will be performed by GDB.

'show agent'
     Display the current setting of execution of debugging operations by
     the in-process agent.

* Menu:

* In-Process Agent Protocol::


File: gdb.info,  Node: In-Process Agent Protocol,  Up: In-Process Agent

30.1 In-Process Agent Protocol
==============================

The in-process agent is able to communicate with both GDB and GDBserver
(*note In-Process Agent::).  This section documents the protocol used
for communications between GDB or GDBserver and the IPA. In general, GDB
or GDBserver sends commands (*note IPA Protocol Commands::) and data to
in-process agent, and then in-process agent replies back with the return
result of the command, or some other information.  The data sent to
in-process agent is composed of primitive data types, such as 4-byte or
8-byte type, and composite types, which are called objects (*note IPA
Protocol Objects::).

* Menu:

* IPA Protocol Objects::
* IPA Protocol Commands::


File: gdb.info,  Node: IPA Protocol Objects,  Next: IPA Protocol Commands,  Up: In-Process Agent Protocol

30.1.1 IPA Protocol Objects
---------------------------

The commands sent to and results received from agent may contain some
complex data types called "objects".

   The in-process agent is running on the same machine with GDB or
GDBserver, so it doesn't have to handle as much differences between two
ends as remote protocol (*note Remote Protocol::) tries to handle.
However, there are still some differences of two ends in two processes:

  1. word size.  On some 64-bit machines, GDB or GDBserver can be
     compiled as a 64-bit executable, while in-process agent is a 32-bit
     one.
  2. ABI. Some machines may have multiple types of ABI, GDB or GDBserver
     is compiled with one, and in-process agent is compiled with the
     other one.

   Here are the IPA Protocol Objects:

  1. agent expression object.  It represents an agent expression (*note
     Agent Expressions::).
  2. tracepoint action object.  It represents a tracepoint action (*note
     Tracepoint Action Lists: Tracepoint Actions.) to collect registers,
     memory, static trace data and to evaluate expression.
  3. tracepoint object.  It represents a tracepoint (*note
     Tracepoints::).

   The following table describes important attributes of each IPA
protocol object:

Name                   Size           Description
---------------------------------------------------------------------------
_agent expression
object_
length                 4              length of bytes code
byte code              LENGTH         contents of byte code
_tracepoint action
for collecting
memory_
'M'                    1              type of tracepoint action
addr                   8              if BASEREG is '-1', ADDR is the
                                      address of the lowest byte to
                                      collect, otherwise ADDR is the
                                      offset of BASEREG for memory
                                      collecting.
len                    8              length of memory for collecting
basereg                4              the register number containing the
                                      starting memory address for
                                      collecting.
_tracepoint action
for collecting
registers_
'R'                    1              type of tracepoint action
_tracepoint action
for collecting
static trace data_
'L'                    1              type of tracepoint action
_tracepoint action
for expression
evaluation_
'X'                    1              type of tracepoint action
agent expression       length of      *note agent expression object::
_tracepoint object_
number                 4              number of tracepoint
address                8              address of tracepoint inserted on
type                   4              type of tracepoint
enabled                1              enable or disable of tracepoint
step_count             8              step
pass_count             8              pass
numactions             4              number of tracepoint actions
hit count              8              hit count
trace frame usage      8              trace frame usage
compiled_cond          8              compiled condition
orig_size              8              orig size
condition              4 if           zero if condition is NULL,
                       condition is   otherwise is
                       NULL           *note agent expression object::
                       otherwise
                       length of
                       *note agent expression object::
actions                variable       numactions number of
                                      *note tracepoint action object::


File: gdb.info,  Node: IPA Protocol Commands,  Prev: IPA Protocol Objects,  Up: In-Process Agent Protocol

30.1.2 IPA Protocol Commands
----------------------------

The spaces in each command are delimiters to ease reading this commands
specification.  They don't exist in real commands.

'FastTrace:TRACEPOINT_OBJECT GDB_JUMP_PAD_HEAD'
     Installs a new fast tracepoint described by TRACEPOINT_OBJECT
     (*note tracepoint object::).  The GDB_JUMP_PAD_HEAD, 8-byte long,
     is the head of "jumppad", which is used to jump to data collection
     routine in IPA finally.

     Replies:
     'OK TARGET_ADDRESS GDB_JUMP_PAD_HEAD FJUMP_SIZE FJUMP'
          TARGET_ADDRESS is address of tracepoint in the inferior.  The
          GDB_JUMP_PAD_HEAD is updated head of jumppad.  Both of
          TARGET_ADDRESS and GDB_JUMP_PAD_HEAD are 8-byte long.  The
          FJUMP contains a sequence of instructions jump to jumppad
          entry.  The FJUMP_SIZE, 4-byte long, is the size of FJUMP.
     'E NN'
          for an error

'close'
     Closes the in-process agent.  This command is sent when GDB or
     GDBserver is about to kill inferiors.

'qTfSTM'
     *Note qTfSTM::.
'qTsSTM'
     *Note qTsSTM::.
'qTSTMat'
     *Note qTSTMat::.
'probe_marker_at:ADDRESS'
     Asks in-process agent to probe the marker at ADDRESS.

     Replies:
     'E NN'
          for an error
'unprobe_marker_at:ADDRESS'
     Asks in-process agent to unprobe the marker at ADDRESS.


File: gdb.info,  Node: GDB Bugs,  Next: Command Line Editing,  Prev: In-Process Agent,  Up: Top

31 Reporting Bugs in GDB
************************

Your bug reports play an essential role in making GDB reliable.

   Reporting a bug may help you by bringing a solution to your problem,
or it may not.  But in any case the principal function of a bug report
is to help the entire community by making the next version of GDB work
better.  Bug reports are your contribution to the maintenance of GDB.

   In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.

* Menu:

* Bug Criteria::                Have you found a bug?
* Bug Reporting::               How to report bugs


File: gdb.info,  Node: Bug Criteria,  Next: Bug Reporting,  Up: GDB Bugs

31.1 Have You Found a Bug?
==========================

If you are not sure whether you have found a bug, here are some
guidelines:

   * If the debugger gets a fatal signal, for any input whatever, that
     is a GDB bug.  Reliable debuggers never crash.

   * If GDB produces an error message for valid input, that is a bug.
     (Note that if you're cross debugging, the problem may also be
     somewhere in the connection to the target.)

   * If GDB does not produce an error message for invalid input, that is
     a bug.  However, you should note that your idea of "invalid input"
     might be our idea of "an extension" or "support for traditional
     practice".

   * If you are an experienced user of debugging tools, your suggestions
     for improvement of GDB are welcome in any case.

