visus
/
toolchain-gcc-arm-embedded

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 1988-2020 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 6.5, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Thread-Specific Breakpoints (Debugging with GDB)</title>

<meta name="description" content="Thread-Specific Breakpoints (Debugging with GDB)">
<meta name="keywords" content="Thread-Specific Breakpoints (Debugging with GDB)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<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="Thread-Stops.html#Thread-Stops" rel="up" title="Thread Stops">
<link href="Interrupted-System-Calls.html#Interrupted-System-Calls" rel="next" title="Interrupted System Calls">
<link href="Background-Execution.html#Background-Execution" rel="prev" title="Background Execution">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
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.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en">
<a name="Thread_002dSpecific-Breakpoints"></a>
<div class="header">
<p>
Next: <a href="Interrupted-System-Calls.html#Interrupted-System-Calls" accesskey="n" rel="next">Interrupted System Calls</a>, Previous: <a href="Background-Execution.html#Background-Execution" accesskey="p" rel="prev">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> &nbsp; [<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="Thread_002dSpecific-Breakpoints-1"></a>
<h4 class="subsection">5.5.4 Thread-Specific Breakpoints</h4>

<p>When your program has multiple threads (see <a href="Threads.html#Threads">Debugging
Programs with Multiple Threads</a>), you can choose whether to set
breakpoints on all threads, or on a particular thread.
</p>
<dl compact="compact">
<dd><a name="index-breakpoints-and-threads"></a>
<a name="index-thread-breakpoints"></a>
<a name="index-break-_2026-thread-thread_002did"></a>
</dd>
<dt><code>break <var>location</var> thread <var>thread-id</var></code></dt>
<dt><code>break <var>location</var> thread <var>thread-id</var> if &hellip;</code></dt>
<dd><p><var>location</var> specifies source lines; there are several ways of
writing them (see <a href="Specify-Location.html#Specify-Location">Specify Location</a>), but the effect is always to
specify some source line.
</p>
<p>Use the qualifier &lsquo;<samp>thread <var>thread-id</var></samp>&rsquo; with a breakpoint command
to specify that you only want <small>GDB</small> to stop the program when a
particular thread reaches this breakpoint.  The <var>thread-id</var> specifier
is one of the thread identifiers assigned by <small>GDB</small>, shown
in the first column of the &lsquo;<samp>info threads</samp>&rsquo; display.
</p>
<p>If you do not specify &lsquo;<samp>thread <var>thread-id</var></samp>&rsquo; when you set a
breakpoint, the breakpoint applies to <em>all</em> threads of your
program.
</p>
<p>You can use the <code>thread</code> qualifier on conditional breakpoints as
well; in this case, place &lsquo;<samp>thread <var>thread-id</var></samp>&rsquo; before or
after the breakpoint condition, like this:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) break frik.c:13 thread 28 if bartab &gt; lim
</pre></div>

</dd>
</dl>

<p>Thread-specific breakpoints are automatically deleted when
<small>GDB</small> detects the corresponding thread is no longer in the
thread list.  For example:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) c
Thread-specific breakpoint 3 deleted - thread 28 no longer in the thread list.
</pre></div>

<p>There are several ways for a thread to disappear, such as a regular
thread exit, but also when you detach from the process with the
<code>detach</code> command (see <a href="Attach.html#Attach">Debugging an Already-running
Process</a>), or if <small>GDB</small> loses the remote connection
(see <a href="Remote-Debugging.html#Remote-Debugging">Remote Debugging</a>), etc.  Note that with some targets,
<small>GDB</small> is only able to detect a thread has exited when the user
explictly asks for the thread list with the <code>info threads</code>
command.
</p>
<hr>
<div class="header">
<p>
Next: <a href="Interrupted-System-Calls.html#Interrupted-System-Calls" accesskey="n" rel="next">Interrupted System Calls</a>, Previous: <a href="Background-Execution.html#Background-Execution" accesskey="p" rel="prev">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> &nbsp; [<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>