Subversion Repositories or1k

@c  \input texinfo   @c -*-texinfo-*-

@c  @c %**start of header

@c  @setfilename gdbmi.info

@c  @settitle GDB/MI Machine Interface

@c  @setchapternewpage off

@c  @c %**end of header

@c  @ifinfo

@c  This file documents GDB/MI, a Machine Interface to GDB.

@c  Copyright (C) 2000, Free Software Foundation, Inc.

@c  Contributed by Cygnus Solutions.

@c  Permission is granted to make and distribute verbatim copies of this

@c  manual provided the copyright notice and this permission notice are

@c  preserved on all copies.

@c  @ignore

@c  Permission is granted to process this file through TeX and print the

@c  results, provided the printed document carries copying permission notice

@c  identical to this one except for the removal of this paragraph (this

@c  paragraph not being relevant to the printed manual).

@c  @end ignore

@c  Permission is granted to copy and distribute modified versions of this

@c  manual under the conditions for verbatim copying, provided also that the

@c  entire resulting derived work is distributed under the terms of a

@c  permission notice identical to this one.

@c  Permission is granted to copy and distribute translations of this manual

@c  into another language, under the above conditions for modified versions.

@c  @end ifinfo

@c  @c  This title page illustrates only one of the

@c  @c  two methods of forming a title page.

@c  @titlepage

@c  @title GDB/MI

@c  @subtitle Version 0.2

@c  @subtitle Feb 2000

@c  @author Andrew Cagney, Fernando Nasser and Elena Zannoni

@c  @c  The following two commands

@c  @c  start the copyright page.

@c  @page

@c  @vskip 0pt plus 1filll

@c  Permission is granted to make and distribute verbatim copies of this

@c  manual provided the copyright notice and this permission notice are

@c  preserved on all copies.

@c  Copyright @copyright{} 2000, Free Software Foundation, Inc.

@c  @end titlepage

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% CHAPTER %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI

@chapter The @sc{gdb/mi} Interface

@unnumberedsec Function and Purpose

@cindex @sc{gdb/mi}, its purpose

@sc{gdb/mi} is a line based machine oriented text interface to GDB.  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 @sc{gdb/mi} interface.  It is written

in the form of a reference manual.

Note that @sc{gdb/mi} is still under construction, so some of the

features described below are incomplete and subject to change.

@unnumberedsec Notation and Terminology

@cindex notational conventions, for @sc{gdb/mi}

This chapter uses the following notation:

@itemize @bullet

@item

@code{|} separates two alternatives.

@item

@code{[ @var{something} ]} indicates that @var{something} is optional:

it may or may not be given.

@item

@code{( @var{group} )*} means that @var{group} inside the parentheses

may repeat zero or more times.

@item

@code{( @var{group} )+} means that @var{group} inside the parentheses

may repeat one or more times.

@item

@code{"@var{string}"} means a literal @var{string}.

@end itemize

@ignore

@heading Dependencies

@end ignore

@heading Acknowledgments

In alphabetic order: Andrew Cagney, Fernando Nasser, Stan Shebs and

Elena Zannoni.

@menu

* GDB/MI Command Syntax::

* GDB/MI Compatibility with CLI::

* GDB/MI Output Records::

* GDB/MI Command Description Format::

* GDB/MI Breakpoint Table Commands::

* GDB/MI Data Manipulation::

* GDB/MI Program Control::

* GDB/MI Miscellaneous Commands::

* GDB/MI Stack Manipulation::

* GDB/MI Symbol Query::

* GDB/MI Target Manipulation::

* GDB/MI Thread Commands::

* GDB/MI Tracepoint Commands::

* GDB/MI Variable Objects::

* GDB/MI Draft Changes to Output Syntax::

@end menu

@c When these are implemented, they should be moved to be between Misc and

@c Stack Manipulation in the above menu.  They are now outside the menu

@c because makeinfo 3.12 barfs if it sees @ignore or @comments in the

@c middle of a menu.

@ignore

* GDB/MI Kod Commands::

* GDB/MI Memory Overlay Commands::

* GDB/MI Signal Handling Commands::

@end ignore

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI Command Syntax

@section @sc{gdb/mi} Command Syntax

@menu

* GDB/MI Input Syntax::

* GDB/MI Output Syntax::

* GDB/MI Simple Examples::

@end menu

@node GDB/MI Input Syntax

@subsection @sc{gdb/mi} Input Syntax

@cindex input syntax for @sc{gdb/mi}

@cindex @sc{gdb/mi}, input syntax

@table @code

@item @var{command} @expansion{}

@code{@var{cli-command} | @var{mi-command}}

@item @var{cli-command} @expansion{}

@code{[ @var{token} ] @var{cli-command} @var{nl}}, where

@var{cli-command} is any existing GDB CLI command.

@item @var{mi-command} @expansion{}

@code{[ @var{token} ] "-" @var{operation} ( " " @var{option} )*

@code{[} " --" @code{]} ( " " @var{parameter} )* @var{nl}}

@item @var{token} @expansion{}

@code{"any sequence of digits"}

@item @var{option} @expansion{}

@code{"-" @var{parameter} [ " " @var{parameter} ]}

@item @var{parameter} @expansion{}

@code{@var{non-blank-sequence} | @var{c-string}}

@item @var{operation} @expansion{}

@emph{any of the operations described in this document}

@item @var{non-blank-sequence} @expansion{}

@emph{anything, provided it doesn't contain special characters such as

"-", @var{nl}, """ and of course " "}

@item @var{c-string} @expansion{}

@code{""" @var{seven-bit-iso-c-string-content} """}

@item @var{nl} @expansion{}

@code{CR | CR-LF}

@end table

Notes:

@itemize @bullet

@item

The CLI commands are still handled by the @sc{mi} interpreter; their

output is described below.

@item

The @code{@var{token}}, when present, is passed back when the command

finishes.

@item

Some @sc{mi} commands accept optional arguments as part of the parameter

list. Each option is identified by a leading @samp{-} (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

@samp{--} (this is useful when some parameters begin with a dash).

@end itemize

Pragmatics:

@itemize @bullet

@item

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

@item

We want it to be easy to spot a @sc{mi} operation.

@end itemize

@node GDB/MI Output Syntax

@subsection @sc{gdb/mi} Output Syntax

@cindex output syntax of @sc{gdb/mi}

@cindex @sc{gdb/mi}, output syntax

The output from @sc{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 @samp{(gdb)}.

If an input command was prefixed with a @code{@var{token}} then the

corresponding output for that command will also be prefixed by that same

@var{token}.

@table @code

@item @var{output} @expansion{}

@code{( @var{out-of-band-record} )* [ @var{result-record} ] "(gdb)" @var{nl}}

@item @var{result-record} @expansion{}

@code{ [ @var{token} ] "^" @var{result-class} ( "," @var{result} )* @var{nl}}

@item @var{out-of-band-record} @expansion{}

@code{@var{async-record} | @var{stream-record}}

@item @var{async-record} @expansion{}

@code{@var{exec-async-output} | @var{status-async-output} | @var{notify-async-output}}

@item @var{exec-async-output} @expansion{}

@code{[ @var{token} ] "*" @var{async-output}}

@item @var{status-async-output} @expansion{}

@code{[ @var{token} ] "+" @var{async-output}}

@item @var{notify-async-output} @expansion{}

@code{[ @var{token} ] "=" @var{async-output}}

@item @var{async-output} @expansion{}

@code{@var{async-class} ( "," @var{result} )* @var{nl}}

@item @var{result-class} @expansion{}

@code{"done" | "running" | "connected" | "error" | "exit"}

@item @var{async-class} @expansion{}

@code{"stopped" | @var{others}} (where @var{others} will be added

depending on the needs---this is still in development).

@item @var{result} @expansion{}

@code{[ @var{string} "=" ] @var{value}}

@item @var{value} @expansion{}

@code{@var{const} | "@{" @var{result} ( "," @var{result} )* "@}"}

@item @var{const} @expansion{}

@code{@var{c-string}}

@item @var{stream-record} @expansion{}

@code{@var{console-stream-output} | @var{target-stream-output} | @var{log-stream-output}}

@item @var{console-stream-output} @expansion{}

@code{"~" @var{c-string}}

@item @var{target-stream-output} @expansion{}

@code{"@@" @var{c-string}}

@item @var{log-stream-output} @expansion{}

@code{"&" @var{c-string}}

@item @var{nl} @expansion{}

@code{CR | CR-LF}

@item @var{token} @expansion{}

@emph{any sequence of digits}.

@end table

In addition, the following are still being developed:

@table @code

@item @var{query}

This action is currently undefined.

@end table

Notes:

@itemize @bullet

@item

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

@item

The @code{@var{token}} is from the corresponding request.  If an execution

command is interrupted by the @samp{-exec-interrupt} command, the

@var{token} associated with the `*stopped' message is the one of the

original execution command, not the one of the interrupt-command.

@item

@cindex status output in @sc{gdb/mi}

@var{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 @samp{+}.

@item

@cindex async output in @sc{gdb/mi}

@var{exec-async-output} contains asynchronous state change on the target

(stopped, started, disappeared).  All async output is prefixed by

@samp{*}.

@item

@cindex notify output in @sc{gdb/mi}

@var{notify-async-output} contains supplementary information that the

client should handle (e.g., a new breakpoint information).  All notify

output is prefixed by @samp{=}.

@item

@cindex console output in @sc{gdb/mi}

@var{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 @samp{~}.

@item

@cindex target output in @sc{gdb/mi}

@var{target-stream-output} is the output produced by the target program.

All the target output is prefixed by @samp{@@}.

@item

@cindex log output in @sc{gdb/mi}

@var{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 @samp{&}.

@end itemize

@xref{GDB/MI Stream Records, , @sc{gdb/mi} Stream Records}, for more

details about the various output records.

@xref{GDB/MI Draft Changes to Output Syntax, , @sc{gdb/mi} Draft Changes

to Output Syntax}, for proposed revisions to the current output syntax.

@node GDB/MI Simple Examples

@subsection Simple Examples of @sc{gdb/mi} Interaction

@cindex @sc{gdb/mi}, simple examples

This subsection presents several simple examples of interaction using

the @sc{gdb/mi} interface.  In these examples, @samp{->} means that the

following line is passed to @sc{gdb/mi} as input, while @samp{<-} means

the output received from @sc{gdb/mi}.

@subsubheading Target Stop

Here's an example of stopping the inferior process:

@example

-> -stop

<- (gdb)

@end example

@noindent

and later:

@example

<- *stop,reason="stop",address="0x123",source="a.c:123"

<- (gdb)

@end example

@subsubheading Simple CLI Command

Here's an example of a simple CLI command being passed through

@sc{gdb/mi} and on to the CLI.

@example

-> print 1+2

<- ~3\n

<- (gdb)

@end example

@subsubheading Command With Side Effects

@example

-> -symbol-file xyz.exe

<- *breakpoint,nr="3",address="0x123",source="a.c:123"

<- (gdb)

@end example

@subsubheading A Bad Command

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

@example

-> -rubbish

<- error,"Rubbish not found"

<- (gdb)

@end example

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI Compatibility with CLI

@section @sc{gdb/mi} Compatibility with CLI

@cindex compatibility, @sc{gdb/mi} and CLI

@cindex @sc{gdb/mi}, compatibility with CLI

To help users familiar with GDB's existing CLI interface, @sc{gdb/mi}

accepts existing CLI commands.  As specified by the syntax, such

commands can be directly entered into the @sc{gdb/mi} interface and GDB will

respond.

This mechanism is provided as an aid to developers of @sc{gdb/mi}

clients and not as a reliable interface into the CLI.  Since the command

is being interpreteted in an environment that assumes @sc{gdb/mi}

behaviour, the exact output of such commands is likely to end up being

an un-supported hybrid of @sc{gdb/mi} and CLI output.

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI Output Records

@section @sc{gdb/mi} Output Records

@menu

* GDB/MI Result Records::

* GDB/MI Stream Records::

* GDB/MI Out-of-band Records::

@end menu

@node GDB/MI Result Records

@subsection @sc{gdb/mi} Result Records

@cindex result records in @sc{gdb/mi}

@cindex @sc{gdb/mi}, result records

In addition to a number of out-of-band notifications, the response to a

@sc{gdb/mi} command includes one of the following result indications:

@table @code

@findex ^done

@item "^done" [ "," @var{results} ]

The synchronous operation was successful, @code{@var{results}} is the return

value.

@item "^running"

@findex ^running

@c Is this one correct?  Should it be an out-of-band notification?

The asynchronous operation was successfully started.  The target is

running.

@item "^error" "," @var{c-string}

@cindex ^error

The operation failed.  The @code{@var{c-string}} contains the corresponding

error message.

@end table

@node GDB/MI Stream Records

@subsection @sc{gdb/mi} Stream Records

@cindex @sc{gdb/mi}, stream records

@cindex stream records in @sc{gdb/mi}

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 @sc{gdb/mi} interface using @dfn{stream records}.

Each stream record begins with a unique @dfn{prefix character} which

identifies its stream (@pxref{GDB/MI Output Syntax, , @sc{gdb/mi} Output

Syntax}). In addition to the prefix, each stream record contains a

@code{@var{string-output}}.  This is either raw text (with an implicit new

line) or a quoted C string (which does not contain an implicit newline).

@table @code

@item "~" @var{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.

@item "@@" @var{string-output}

The target output stream contains any textual output from the running

target.

@item "&" @var{string-output}

The LOG stream contains debugging messages being produced by GDB's

internals.

@end table

@node GDB/MI Out-of-band Records

@subsection @sc{gdb/mi} Out-of-band Records

@cindex out-of-band records in @sc{gdb/mi}

@cindex @sc{gdb/mi}, out-of-band records

@dfn{Out-of-band} records are used to notify the @sc{gdb/mi} client of

additional changes that have occurred.  Those changes can either be a

consequence of @sc{gdb/mi} (e.g., a breakpoint modified) or a result of

target activity (e.g., target stopped).

The following is a preliminary list of possible out-of-band records.

@table @code

@item "*" "stop"

@end table

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI Command Description Format

@section @sc{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 chapter.

Note the the line breaks shown in the examples are here only for

readability. They don't appear in the real output.

Also note that the commands with a non-available example (N.A.@:) are

not yet implemented.

@subheading Motivation

The motivation for this collection of commands

@subheading Introduction

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

@subheading Commands

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

@subsubheading Synopsis

@example

 -command @var{args}...

@end example

@subsubheading GDB Command

The corresponding GDB CLI command.

@subsubheading Result

@subsubheading Out-of-band

@subsubheading Notes

@subsubheading Example

@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@node GDB/MI Breakpoint Table Commands

@section @sc{gdb/mi} Breakpoint table commands

@cindex breakpoint commands for @sc{gdb/mi}

@cindex @sc{gdb/mi}, breakpoint commands

This section documents @sc{gdb/mi} commands for manipulating

breakpoints.

@subheading The @code{-break-after} Command

@findex -break-after

@subsubheading Synopsis

@example

 -break-after @var{number} @var{count}

@end example

The breakpoint number @var{number} is not in effect until it has been

hit @var{count} times.  To see how this is reflected in the output of

the @samp{-break-list} command, see the description of the

@samp{-break-list} command below.

@subsubheading GDB Command

The corresponding GDB command is @samp{ignore}.

@subsubheading Example

@smallexample

(gdb)

-break-insert main

^done,bkpt=@{number="1",addr="0x000100d0",file="hello.c",line="5"@}

(gdb)

-break-after 1 3

~

^done

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",

addr="0x000100d0",func="main",file="hello.c",line="5",times="0",

ignore="3"@}@}

(gdb)

@end smallexample

@ignore

@subheading The @code{-break-catch} Command

@findex -break-catch

@subheading The @code{-break-commands} Command

@findex -break-commands

@end ignore

@subheading -break-condition

@findex -break-condition

@subsubheading Synopsis

@example

 -break-condition @var{number} @var{expr}

@end example

Breakpoint @var{number} will stop the program only if the condition in

@var{expr} is true.  The condition becomes part of the

@samp{-break-list} output (see the description of the @samp{-break-list}

command below).

@subsubheading GDB Command

The corresponding GDB command is @samp{condition}.

@subsubheading Example

@smallexample

(gdb)

-break-condition 1 1

^done

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",

addr="0x000100d0",func="main",file="hello.c",line="5",cond="1",

times="0",ignore="3"@}@}

(gdb)

@end smallexample

@subheading The @code{-break-delete} Command

@findex -break-delete

@subsubheading Synopsis

@example

 -break-delete ( @var{breakpoint} )+

@end example

Delete the breakpoint(s) whose number(s) are specified in the argument

list. This is obviously reflected in the breakpoint list.

@subsubheading GDB command

The corresponding GDB command is @samp{delete}.

@subsubheading Example

@example

(gdb)

-break-delete 1

^done

(gdb)

-break-list

^done,BreakpointTable=@{@}

(gdb)

@end example

@subheading The @code{-break-disable} Command

@findex -break-disable

@subsubheading Synopsis

@example

 -break-disable ( @var{breakpoint} )+

@end example

Disable the named @var{breakpoint}(s).  The field @samp{enabled} in the

break list is now set to @samp{n} for the named @var{breakpoint}(s).

@subsubheading GDB Command

The corresponding GDB command is @samp{disable}.

@subsubheading Example

@smallexample

(gdb)

-break-disable 2

^done

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="2",type="breakpoint",disp="keep",enabled="n",

addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@}@}

(gdb)

@end smallexample

@subheading The @code{-break-enable} Command

@findex -break-enable

@subsubheading Synopsis

@example

 -break-enable ( @var{breakpoint} )+

@end example

Enable (previously disabled) @var{breakpoint}(s).

@subsubheading GDB Command

The corresponding GDB command is @samp{enable}.

@subsubheading Example

@smallexample

(gdb)

-break-enable 2

^done

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",

addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@}@}

(gdb)

@end smallexample

@subheading The @code{-break-info} Command

@findex -break-info

@subsubheading Synopsis

@example

 -break-info @var{breakpoint}

@end example

@c REDUNDANT???

Get information about a single breakpoint.

@subsubheading GDB command

The corresponding GDB command is @samp{info break @var{breakpoint}}.

@subsubheading Example

N.A.

@subheading The @code{-break-insert} Command

@findex -break-insert

@subsubheading Synopsis

@example

 -break-insert [ -t ] [ -h ] [ -r ]

    [ -c @var{condition} ] [ -i @var{ignore-count} ]

    [ -p @var{thread} ] [ @var{line} | @var{addr} ]

@end example

@noindent

If specified, @var{line}, can be one of:

@itemize @bullet

@item function

@c @item +offset

@c @item -offset

@c @item linenum

@item filename:linenum

@item filename:function

@item *address

@end itemize

The possible optional parameters of this command are:

@table @samp

@item -t

Insert a tempoary breakpoint.

@item -h

Insert a hardware breakpoint.

@item -c @var{condition}

Make the breakpoint conditional on @var{condition}.

@item -i @var{ignore-count}

Initialize the @var{ignore-count}.

@item -r

Insert a regular breakpoint in all the functions whose names match the

given regular expression.  Other flags are not applicable to regular

expresson.

@end table

@subsubheading Result

The result is in the form:

@example

 ^done,bkptno="@var{number}",func="@var{funcname}",

  file="@var{filename}",line="@var{lineno}"

@end example

@noindent

where @var{number} is the GDB number for this breakpoint, @var{funcname}

is the name of the function where the breakpoint was inserted,

@var{filename} is the name of the source file which contains this

function, and @var{lineno} is the source line number within that file.

Note: this format is open to change.

@c An out-of-band breakpoint instead of part of the result?

@subsubheading GDB Command

The corresponding GDB commands are @samp{break}, @samp{tbreak},

@samp{hbreak}, @samp{thbreak}, and @samp{rbreak}.

@subsubheading Example

@smallexample

(gdb)

-break-insert main

^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@}

(gdb)

-break-insert -t foo

^done,bkpt=@{number="2",addr="0x00010774",file="recursive2.c",line="11"@}

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",

addr="0x0001072c", func="main",file="recursive2.c",line="4",times="0"@},

bkpt=@{number="2",type="breakpoint",disp="del",enabled="y",

addr="0x00010774",func="foo",file="recursive2.c",line="11",times="0"@}@}

(gdb)

-break-insert -r foo.*

~int foo(int, int);

^done,bkpt=@{number="3",addr="0x00010774",file="recursive2.c",line="11"@}

(gdb)

@end smallexample

@subheading The @code{-break-list} Command

@findex -break-list

@subsubheading Synopsis

@example

 -break-list

@end example

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

@table @samp

@item Number

number of the breakpoint

@item Type

type of the breakpoint: @samp{breakpoint} or @samp{watchpoint}

@item Disposition

should the breakpoint be deleted or disabled when it is hit: @samp{keep}

or @samp{nokeep}

@item Enabled

is the breakpoint enabled or no: @samp{y} or @samp{n}

@item Address

memory location at which the breakpoint is set

@item What

logical location of the breakpoint, expressed by function name, file

name, line number

@item times

number of times the breakpoint has been hit

@end table

If there are no breakpoints or watchpoints, the BreakpointTable field is

an empty list.

@subsubheading GDB Command

The corresponding GDB command is @samp{info break}.

@subsubheading Example

@smallexample

(gdb)

-break-list

^done,BreakpointTable=@{hdr=@{"Num","Type","Disp","Enb","Address","What"@},

bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",

addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@},

bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",

addr="0x00010114",func="foo",file="hello.c",line="13",times="0"@}@}

(gdb)

@end smallexample

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

@smallexample

(gdb)

-break-list

^done,BreakpointTable=@{@}

(gdb)

@end smallexample

@subheading The @code{-break-watch} Command

@findex -break-watch

@subsubheading Synopsis

@example

 -break-watch [ -a | -r ]

@end example

Create a watchpoint.  With the @samp{-a} option it will create an

@dfn{access} watchpoint, i.e. a watchpoint that triggers either on a

read from or on a write to the memory location.  With the @samp{-r}

option, the watchpoint created is a @dfn{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.

@xref{Set Watchpoints, , Setting watchpoints}.

Note that @samp{-break-list} will report a single list of watchpoints and

breakpoints inserted.

@subsubheading GDB Command

The corresponding GDB commands are @samp{watch}, @samp{awatch}, and

@samp{rwatch}.

@subsubheading Example

Setting a watchpoint on a variable in the @code{main} function:

@smallexample

(gdb)

-break-watch x

^done,wpt=@{number="2",exp="x"@}

(gdb)

-exec-continue

^running

^done,reason="watchpoint-trigger",wpt=@{number="2",exp="x"@},

value=@{old="-268439212",new="55"@},

frame=@{func="main",args=@{@},file="recursive2.c",line="5"@}

(gdb)

@end smallexample

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.

@smallexample

(gdb)

-break-watch C

^done,wpt=@{number="5",exp="C"@}

(gdb)

-exec-continue

^running

^done,reason="watchpoint-trigger",

wpt=@{number="5",exp="C"@},value=@{old="-276895068",new="3"@},