94 lines
4.7 KiB
HTML
94 lines
4.7 KiB
HTML
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Tracepoints - Debugging with GDB</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Debugging with GDB">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="prev" href="Macros.html#Macros" title="Macros">
|
||
|
|
<link rel="next" href="Overlays.html#Overlays" title="Overlays">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
Copyright (C) 1988-2019 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.''
|
||
|
|
-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="Tracepoints"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="Overlays.html#Overlays">Overlays</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Macros.html#Macros">Macros</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h2 class="chapter">13 Tracepoints</h2>
|
||
|
|
|
||
|
|
<!-- This chapter is based on the documentation written by Michael -->
|
||
|
|
<!-- Snyder, David Taylor, Jim Blandy, and Elena Zannoni. -->
|
||
|
|
<p><a name="index-tracepoints-858"></a>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 change its behavior drastically, or perhaps
|
||
|
|
fail, even when the code itself is correct. It is useful to be able
|
||
|
|
to observe the program's behavior without interrupting it.
|
||
|
|
|
||
|
|
<p>Using <span class="sc">gdb</span>'s <code>trace</code> and <code>collect</code> commands, you can
|
||
|
|
specify locations in the program, called <dfn>tracepoints</dfn>, and
|
||
|
|
arbitrary expressions to evaluate when those tracepoints are reached.
|
||
|
|
Later, using the <code>tfind</code> command, you can examine the values
|
||
|
|
those expressions had when the program hit the tracepoints. The
|
||
|
|
expressions may also denote objects in memory—structures or arrays,
|
||
|
|
for example—whose values <span class="sc">gdb</span> should record; while visiting
|
||
|
|
a particular tracepoint, you may inspect those objects as if they were
|
||
|
|
in memory at that moment. However, because <span class="sc">gdb</span> records these
|
||
|
|
values without interacting with you, it can do so quickly and
|
||
|
|
unobtrusively, hopefully not disturbing the program's behavior.
|
||
|
|
|
||
|
|
<p>The tracepoint facility is currently available only for remote
|
||
|
|
targets. See <a href="Targets.html#Targets">Targets</a>. In addition, your remote target must know
|
||
|
|
how to collect trace data. This functionality is implemented in the
|
||
|
|
remote stub; however, none of the stubs distributed with <span class="sc">gdb</span>
|
||
|
|
support tracepoints as of this writing. The format of the remote
|
||
|
|
packets used to implement tracepoints are described in <a href="Tracepoint-Packets.html#Tracepoint-Packets">Tracepoint Packets</a>.
|
||
|
|
|
||
|
|
<p>It is also possible to get trace data from a file, in a manner reminiscent
|
||
|
|
of corefiles; you specify the filename, and use <code>tfind</code> to search
|
||
|
|
through the file. See <a href="Trace-Files.html#Trace-Files">Trace Files</a>, for more details.
|
||
|
|
|
||
|
|
<p>This chapter describes the tracepoint commands and features.
|
||
|
|
|
||
|
|
<ul class="menu">
|
||
|
|
<li><a accesskey="1" href="Set-Tracepoints.html#Set-Tracepoints">Set Tracepoints</a>
|
||
|
|
<li><a accesskey="2" href="Analyze-Collected-Data.html#Analyze-Collected-Data">Analyze Collected Data</a>
|
||
|
|
<li><a accesskey="3" href="Tracepoint-Variables.html#Tracepoint-Variables">Tracepoint Variables</a>
|
||
|
|
<li><a accesskey="4" href="Trace-Files.html#Trace-Files">Trace Files</a>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|