393 lines
17 KiB
HTML
393 lines
17 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- Copyright (C) 1988-2022 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." -->
|
|
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>Debugging with GDB: Inferiors Connections and Programs</title>
|
|
|
|
<meta name="description" content="Debugging with GDB: Inferiors Connections and Programs">
|
|
<meta name="keywords" content="Debugging with GDB: Inferiors Connections and Programs">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Running.html#Running" rel="up" title="Running">
|
|
<link href="Threads.html#Threads" rel="next" title="Threads">
|
|
<link href="Kill-Process.html#Kill-Process" rel="previous" title="Kill Process">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.indentedblock {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style:oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nocodebreak {white-space:nowrap}
|
|
span.nolinebreak {white-space:nowrap}
|
|
span.roman {font-family:serif; font-weight:normal}
|
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
|
<a name="Inferiors-Connections-and-Programs"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Threads.html#Threads" accesskey="n" rel="next">Threads</a>, Previous: <a href="Kill-Process.html#Kill-Process" accesskey="p" rel="previous">Kill Process</a>, Up: <a href="Running.html#Running" accesskey="u" rel="up">Running</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="Debugging-Multiple-Inferiors-Connections-and-Programs"></a>
|
|
<h3 class="section">4.9 Debugging Multiple Inferiors Connections and Programs</h3>
|
|
|
|
<p><small>GDB</small> lets you run and debug multiple programs in a single
|
|
session. In addition, <small>GDB</small> on some systems may let you run
|
|
several programs simultaneously (otherwise you have to exit from one
|
|
before starting another). On some systems <small>GDB</small> may even let
|
|
you debug several programs simultaneously on different remote systems.
|
|
In the most general case, you can have multiple threads of execution
|
|
in each of multiple processes, launched from multiple executables,
|
|
running on different machines.
|
|
</p>
|
|
<a name="index-inferior"></a>
|
|
<p><small>GDB</small> represents the state of each program execution with an
|
|
object called an <em>inferior</em>. An inferior typically corresponds to
|
|
a process, but is more general and applies also to targets that do not
|
|
have processes. Inferiors may be created before a process runs, and
|
|
may be retained after a process exits. Inferiors have unique
|
|
identifiers that are different from process ids. Usually each
|
|
inferior will also have its own distinct address space, although some
|
|
embedded targets may have several inferiors running in different parts
|
|
of a single address space. Each inferior may in turn have multiple
|
|
threads running in it.
|
|
</p>
|
|
<p>To find out what inferiors exist at any moment, use <code>info inferiors</code><!-- /@w -->:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-info-inferiors-_005b-id_2026-_005d"></a>
|
|
</dd>
|
|
<dt><code>info inferiors</code></dt>
|
|
<dd><p>Print a list of all inferiors currently being managed by <small>GDB</small>.
|
|
By default all inferiors are printed, but the argument <var>id</var>…
|
|
– a space separated list of inferior numbers – can be used to limit
|
|
the display to just the requested inferiors.
|
|
</p>
|
|
<p><small>GDB</small> displays for each inferior (in this order):
|
|
</p>
|
|
<ol>
|
|
<li> the inferior number assigned by <small>GDB</small>
|
|
|
|
</li><li> the target system’s inferior identifier
|
|
|
|
</li><li> the target connection the inferior is bound to, including the unique
|
|
connection number assigned by <small>GDB</small>, and the protocol used by
|
|
the connection.
|
|
|
|
</li><li> the name of the executable the inferior is running.
|
|
|
|
</li></ol>
|
|
|
|
<p>An asterisk ‘<samp>*</samp>’ preceding the <small>GDB</small> inferior number
|
|
indicates the current inferior.
|
|
</p>
|
|
<p>For example,
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) info inferiors
|
|
Num Description Connection Executable
|
|
* 1 process 3401 1 (native) goodbye
|
|
2 process 2307 2 (extended-remote host:10000) hello
|
|
</pre></div>
|
|
|
|
<p>To get informations about the current inferior, use <code>inferior</code>:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-inferior-1"></a>
|
|
</dd>
|
|
<dt><code>inferior</code></dt>
|
|
<dd><p>Shows information about the current inferior.
|
|
</p>
|
|
<p>For example,
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) inferior
|
|
[Current inferior is 1 [process 3401] (helloworld)]
|
|
</pre></div>
|
|
|
|
<p>To find out what open target connections exist at any moment, use
|
|
<code>info connections</code><!-- /@w -->:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-info-connections-_005b-id_2026-_005d"></a>
|
|
</dd>
|
|
<dt><code>info connections</code></dt>
|
|
<dd><p>Print a list of all open target connections currently being managed by
|
|
<small>GDB</small>. By default all connections are printed, but the
|
|
argument <var>id</var>… – a space separated list of connections
|
|
numbers – can be used to limit the display to just the requested
|
|
connections.
|
|
</p>
|
|
<p><small>GDB</small> displays for each connection (in this order):
|
|
</p>
|
|
<ol>
|
|
<li> the connection number assigned by <small>GDB</small>.
|
|
|
|
</li><li> the protocol used by the connection.
|
|
|
|
</li><li> a textual description of the protocol used by the connection.
|
|
|
|
</li></ol>
|
|
|
|
<p>An asterisk ‘<samp>*</samp>’ preceding the connection number indicates the
|
|
connection of the current inferior.
|
|
</p>
|
|
<p>For example,
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) info connections
|
|
Num What Description
|
|
* 1 extended-remote host:10000 Extended remote serial target in gdb-specific protocol
|
|
2 native Native process
|
|
3 core Local core dump file
|
|
</pre></div>
|
|
|
|
<p>To switch focus between inferiors, use the <code>inferior</code> command:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-inferior-infno"></a>
|
|
</dd>
|
|
<dt><code>inferior <var>infno</var></code></dt>
|
|
<dd><p>Make inferior number <var>infno</var> the current inferior. The argument
|
|
<var>infno</var> is the inferior number assigned by <small>GDB</small>, as shown
|
|
in the first field of the ‘<samp>info inferiors</samp>’ display.
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<a name="index-_0024_005finferior_002c-convenience-variable"></a>
|
|
<p>The debugger convenience variable ‘<samp>$_inferior</samp>’ contains the
|
|
number of the current inferior. You may find this useful in writing
|
|
breakpoint conditional expressions, command scripts, and so forth.
|
|
See <a href="Convenience-Vars.html#Convenience-Vars">Convenience Variables</a>, for general
|
|
information on convenience variables.
|
|
</p>
|
|
<p>You can get multiple executables into a debugging session via the
|
|
<code>add-inferior</code> and <code><span class="nolinebreak">clone-inferior</span></code><!-- /@w --> commands. On some
|
|
systems <small>GDB</small> can add inferiors to the debug session
|
|
automatically by following calls to <code>fork</code> and <code>exec</code>. To
|
|
remove inferiors from the debugging session use the
|
|
<code><span class="nolinebreak">remove-inferiors</span></code><!-- /@w --> command.
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="add_005finferior_005fcli"></a><a name="index-add_002dinferior"></a>
|
|
</dd>
|
|
<dt><code>add-inferior [ -copies <var>n</var> ] [ -exec <var>executable</var> ] [-no-connection ]</code></dt>
|
|
<dd><p>Adds <var>n</var> inferiors to be run using <var>executable</var> as the
|
|
executable; <var>n</var> defaults to 1. If no executable is specified,
|
|
the inferiors begins empty, with no program. You can still assign or
|
|
change the program assigned to the inferior at any time by using the
|
|
<code>file</code> command with the executable name as its argument.
|
|
</p>
|
|
<p>By default, the new inferior begins connected to the same target
|
|
connection as the current inferior. For example, if the current
|
|
inferior was connected to <code>gdbserver</code> with <code>target remote</code>,
|
|
then the new inferior will be connected to the same <code>gdbserver</code>
|
|
instance. The ‘<samp>-no-connection</samp>’ option starts the new inferior
|
|
with no connection yet. You can then for example use the <code>target
|
|
remote</code> command to connect to some other <code>gdbserver</code> instance,
|
|
use <code>run</code> to spawn a local program, etc.
|
|
</p>
|
|
<a name="index-clone_002dinferior"></a>
|
|
</dd>
|
|
<dt><code>clone-inferior [ -copies <var>n</var> ] [ <var>infno</var> ]</code></dt>
|
|
<dd><p>Adds <var>n</var> inferiors ready to execute the same program as inferior
|
|
<var>infno</var>; <var>n</var> defaults to 1, and <var>infno</var> defaults to the
|
|
number of the current inferior. This command copies the values of the
|
|
<var>args</var>, <var><span class="nolinebreak">inferior-tty</span></var><!-- /@w --> and <var>cwd</var> properties from the
|
|
current inferior to the new one. It also propagates changes the user
|
|
made to environment variables using the <code>set environment</code><!-- /@w --> and
|
|
<code>unset environment</code><!-- /@w --> commands. This is a convenient command
|
|
when you want to run another instance of the inferior you are debugging.
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) info inferiors
|
|
Num Description Connection Executable
|
|
* 1 process 29964 1 (native) helloworld
|
|
(gdb) clone-inferior
|
|
Added inferior 2.
|
|
1 inferiors added.
|
|
(gdb) info inferiors
|
|
Num Description Connection Executable
|
|
* 1 process 29964 1 (native) helloworld
|
|
2 <null> 1 (native) helloworld
|
|
</pre></div>
|
|
|
|
<p>You can now simply switch focus to inferior 2 and run it.
|
|
</p>
|
|
<a name="index-remove_002dinferiors"></a>
|
|
</dd>
|
|
<dt><code>remove-inferiors <var>infno</var>…</code></dt>
|
|
<dd><p>Removes the inferior or inferiors <var>infno</var>…. It is not
|
|
possible to remove an inferior that is running with this command. For
|
|
those, use the <code>kill</code> or <code>detach</code> command first.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
<p>To quit debugging one of the running inferiors that is not the current
|
|
inferior, you can either detach from it by using the <code>detach inferior</code><!-- /@w --> command (allowing it to run independently), or kill it
|
|
using the <code>kill inferiors</code><!-- /@w --> command:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-detach-inferiors-infno_2026"></a>
|
|
</dd>
|
|
<dt><code>detach inferior <var>infno</var>…</code></dt>
|
|
<dd><p>Detach from the inferior or inferiors identified by <small>GDB</small>
|
|
inferior number(s) <var>infno</var>…. Note that the inferior’s entry
|
|
still stays on the list of inferiors shown by <code>info inferiors</code>,
|
|
but its Description will show ‘<samp><null></samp>’.
|
|
</p>
|
|
<a name="index-kill-inferiors-infno_2026"></a>
|
|
</dd>
|
|
<dt><code>kill inferiors <var>infno</var>…</code></dt>
|
|
<dd><p>Kill the inferior or inferiors identified by <small>GDB</small> inferior
|
|
number(s) <var>infno</var>…. Note that the inferior’s entry still
|
|
stays on the list of inferiors shown by <code>info inferiors</code>, but its
|
|
Description will show ‘<samp><null></samp>’.
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<p>After the successful completion of a command such as <code>detach</code>,
|
|
<code>detach inferiors</code>, <code>kill</code> or <code>kill inferiors</code>, or after
|
|
a normal process exit, the inferior is still valid and listed with
|
|
<code>info inferiors</code>, ready to be restarted.
|
|
</p>
|
|
|
|
<p>To be notified when inferiors are started or exit under <small>GDB</small>’s
|
|
control use <code>set print <span class="nolinebreak">inferior-events</span></code><!-- /@w -->:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-set-print-inferior_002devents"></a>
|
|
<a name="index-print-messages-on-inferior-start-and-exit"></a>
|
|
</dd>
|
|
<dt><code>set print inferior-events</code></dt>
|
|
<dt><code>set print inferior-events on</code></dt>
|
|
<dt><code>set print inferior-events off</code></dt>
|
|
<dd><p>The <code>set print inferior-events</code> command allows you to enable or
|
|
disable printing of messages when <small>GDB</small> notices that new
|
|
inferiors have started or that inferiors have exited or have been
|
|
detached. By default, these messages will be printed.
|
|
</p>
|
|
<a name="index-show-print-inferior_002devents"></a>
|
|
</dd>
|
|
<dt><code>show print inferior-events</code></dt>
|
|
<dd><p>Show whether messages will be printed when <small>GDB</small> detects that
|
|
inferiors have started, exited or have been detached.
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<p>Many commands will work the same with multiple programs as with a
|
|
single program: e.g., <code>print myglobal</code> will simply display the
|
|
value of <code>myglobal</code> in the current inferior.
|
|
</p>
|
|
|
|
<p>Occasionally, when debugging <small>GDB</small> itself, it may be useful to
|
|
get more info about the relationship of inferiors, programs, address
|
|
spaces in a debug session. You can do that with the <code>maint info <span class="nolinebreak">program-spaces</span></code><!-- /@w --> command.
|
|
</p>
|
|
<dl compact="compact">
|
|
<dd><a name="index-maint-info-program_002dspaces"></a>
|
|
</dd>
|
|
<dt><code>maint info program-spaces</code></dt>
|
|
<dd><p>Print a list of all program spaces currently being managed by
|
|
<small>GDB</small>.
|
|
</p>
|
|
<p><small>GDB</small> displays for each program space (in this order):
|
|
</p>
|
|
<ol>
|
|
<li> the program space number assigned by <small>GDB</small>
|
|
|
|
</li><li> the name of the executable loaded into the program space, with e.g.,
|
|
the <code>file</code> command.
|
|
|
|
</li></ol>
|
|
|
|
<p>An asterisk ‘<samp>*</samp>’ preceding the <small>GDB</small> program space number
|
|
indicates the current program space.
|
|
</p>
|
|
<p>In addition, below each program space line, <small>GDB</small> prints extra
|
|
information that isn’t suitable to display in tabular form. For
|
|
example, the list of inferiors bound to the program space.
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) maint info program-spaces
|
|
Id Executable
|
|
* 1 hello
|
|
2 goodbye
|
|
Bound inferiors: ID 1 (process 21561)
|
|
</pre></div>
|
|
|
|
<p>Here we can see that no inferior is running the program <code>hello</code>,
|
|
while <code>process 21561</code> is running the program <code>goodbye</code>. On
|
|
some targets, it is possible that multiple inferiors are bound to the
|
|
same program space. The most common example is that of debugging both
|
|
the parent and child processes of a <code>vfork</code> call. For example,
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">(gdb) maint info program-spaces
|
|
Id Executable
|
|
* 1 vfork-test
|
|
Bound inferiors: ID 2 (process 18050), ID 1 (process 18045)
|
|
</pre></div>
|
|
|
|
<p>Here, both inferior 2 and inferior 1 are running in the same program
|
|
space as a result of inferior 1 having executed a <code>vfork</code> call.
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Threads.html#Threads" accesskey="n" rel="next">Threads</a>, Previous: <a href="Kill-Process.html#Kill-Process" accesskey="p" rel="previous">Kill Process</a>, Up: <a href="Running.html#Running" accesskey="u" rel="up">Running</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|