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<title>Debugging with GDB: Set Tracepoints</title>
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<a name="Set-Tracepoints"></a>
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<p>
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Next: <a href="Analyze-Collected-Data.html#Analyze-Collected-Data" accesskey="n" rel="next">Analyze Collected Data</a>, Up: <a href="Tracepoints.html#Tracepoints" accesskey="u" rel="up">Tracepoints</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>
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<hr>
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<a name="Commands-to-Set-Tracepoints"></a>
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<h3 class="section">13.1 Commands to Set Tracepoints</h3>
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<p>Before running such a <em>trace experiment</em>, an arbitrary number of
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tracepoints can be set. A tracepoint is actually a special type of
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breakpoint (see <a href="Set-Breaks.html#Set-Breaks">Set Breaks</a>), so you can manipulate it using
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standard breakpoint commands. For instance, as with breakpoints,
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tracepoint numbers are successive integers starting from one, and many
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of the commands associated with tracepoints take the tracepoint number
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as their argument, to identify which tracepoint to work on.
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</p>
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<p>For each tracepoint, you can specify, in advance, some arbitrary set
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of data that you want the target to collect in the trace buffer when
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it hits that tracepoint. The collected data can include registers,
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local variables, or global data. Later, you can use <small>GDB</small>
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commands to examine the values these data had at the time the
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tracepoint was hit.
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</p>
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<p>Tracepoints do not support every breakpoint feature. Ignore counts on
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tracepoints have no effect, and tracepoints cannot run <small>GDB</small>
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commands when they are hit. Tracepoints may not be thread-specific
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either.
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</p>
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<a name="index-fast-tracepoints"></a>
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<p>Some targets may support <em>fast tracepoints</em>, which are inserted in
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a different way (such as with a jump instead of a trap), that is
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faster but possibly restricted in where they may be installed.
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</p>
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<a name="index-static-tracepoints"></a>
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<a name="index-markers_002c-static-tracepoints"></a>
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<a name="index-probing-markers_002c-static-tracepoints"></a>
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<p>Regular and fast tracepoints are dynamic tracing facilities, meaning
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that they can be used to insert tracepoints at (almost) any location
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in the target. Some targets may also support controlling <em>static
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tracepoints</em> from <small>GDB</small>. With static tracing, a set of
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instrumentation points, also known as <em>markers</em>, are embedded in
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the target program, and can be activated or deactivated by name or
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address. These are usually placed at locations which facilitate
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investigating what the target is actually doing. <small>GDB</small>’s
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support for static tracing includes being able to list instrumentation
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points, and attach them with <small>GDB</small> defined high level
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tracepoints that expose the whole range of convenience of
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<small>GDB</small>’s tracepoints support. Namely, support for collecting
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registers values and values of global or local (to the instrumentation
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point) variables; tracepoint conditions and trace state variables.
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The act of installing a <small>GDB</small> static tracepoint on an
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instrumentation point, or marker, is referred to as <em>probing</em> a
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static tracepoint marker.
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</p>
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<p><code>gdbserver</code> supports tracepoints on some target systems.
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See <a href="Server.html#Server">Tracepoints support in <code>gdbserver</code></a>.
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</p>
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<p>This section describes commands to set tracepoints and associated
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conditions and actions.
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</p>
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<table class="menu" border="0" cellspacing="0">
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<tr><td align="left" valign="top">• <a href="Create-and-Delete-Tracepoints.html#Create-and-Delete-Tracepoints" accesskey="1">Create and Delete Tracepoints</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Enable-and-Disable-Tracepoints.html#Enable-and-Disable-Tracepoints" accesskey="2">Enable and Disable Tracepoints</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Tracepoint-Passcounts.html#Tracepoint-Passcounts" accesskey="3">Tracepoint Passcounts</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Tracepoint-Conditions.html#Tracepoint-Conditions" accesskey="4">Tracepoint Conditions</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Trace-State-Variables.html#Trace-State-Variables" accesskey="5">Trace State Variables</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Tracepoint-Actions.html#Tracepoint-Actions" accesskey="6">Tracepoint Actions</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Listing-Tracepoints.html#Listing-Tracepoints" accesskey="7">Listing Tracepoints</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Listing-Static-Tracepoint-Markers.html#Listing-Static-Tracepoint-Markers" accesskey="8">Listing Static Tracepoint Markers</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Starting-and-Stopping-Trace-Experiments.html#Starting-and-Stopping-Trace-Experiments" accesskey="9">Starting and Stopping Trace Experiments</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Tracepoint-Restrictions.html#Tracepoint-Restrictions">Tracepoint Restrictions</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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</table>
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<div class="header">
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<p>
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Next: <a href="Analyze-Collected-Data.html#Analyze-Collected-Data" accesskey="n" rel="next">Analyze Collected Data</a>, Up: <a href="Tracepoints.html#Tracepoints" accesskey="u" rel="up">Tracepoints</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>
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