mingw/info/gdb/Tracepoints.html

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  19 <h2 class="chapter">Tracepoints</h2>
  20
  21    <p>In some applications, it is not feasible for the debugger to interrupt
  22 the program's execution long enough for the developer to learn
  23 anything helpful about its behavior.  If the program's correctness
  24 depends on its real-time behavior, delays introduced by a debugger
  25 might cause the program to change its behavior drastically, or perhaps
  26 fail, even when the code itself is correct.  It is useful to be able
  27 to observe the program's behavior without interrupting it.
  28
  29    <p>Using GDB's <code>trace</code> and <code>collect</code> commands, you can
  30 specify locations in the program, called <dfn>tracepoints</dfn>, and
  31 arbitrary expressions to evaluate when those tracepoints are reached.
  32 Later, using the <code>tfind</code> command, you can examine the values
  33 those expressions had when the program hit the tracepoints.  The
  34 expressions may also denote objects in memory--structures or arrays,
  35 for example--whose values GDB should record; while visiting
  36 a particular tracepoint, you may inspect those objects as if they were
  37 in memory at that moment.  However, because GDB records these
  38 values without interacting with you, it can do so quickly and
  39 unobtrusively, hopefully not disturbing the program's behavior.
  40
  41    <p>The tracepoint facility is currently available only for remote
  42 targets.  See <a href="Targets.html#Targets">Targets</a>.  In addition, your remote target must know how
  43 to collect trace data.  This functionality is implemented in the remote
  44 stub; however, none of the stubs distributed with GDB support
  45 tracepoints as of this writing.
  46
  47    <p>This chapter describes the tracepoint commands and features.
  48
  49 <ul class="menu">
  50 <li><a accesskey="1" href="Set-Tracepoints.html#Set%20Tracepoints">Set Tracepoints</a>:
  51 <li><a accesskey="2" href="Analyze-Collected-Data.html#Analyze%20Collected%20Data">Analyze Collected Data</a>:
  52 <li><a accesskey="3" href="Tracepoint-Variables.html#Tracepoint%20Variables">Tracepoint Variables</a>:
  53 </ul>
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