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<h3 class="section">13.2 Using the Collected Data</h3>

<p>After the tracepoint experiment ends, you use <span class="sc">gdb</span> commands
for examining the trace data.  The basic idea is that each tracepoint
collects a trace <dfn>snapshot</dfn> every time it is hit and another
snapshot every time it single-steps.  All these snapshots are
consecutively numbered from zero and go into a buffer, and you can
examine them later.  The way you examine them is to <dfn>focus</dfn> on a
specific trace snapshot.  When the remote stub is focused on a trace
snapshot, it will respond to all <span class="sc">gdb</span> requests for memory and
registers by reading from the buffer which belongs to that snapshot,
rather than from <em>real</em> memory or registers of the program being
debugged.  This means that <strong>all</strong> <span class="sc">gdb</span> commands
(<code>print</code>, <code>info registers</code>, <code>backtrace</code>, etc.) will
behave as if we were currently debugging the program state as it was
when the tracepoint occurred.  Any requests for data that are not in
the buffer will fail.

<ul class="menu">
<li><a accesskey="1" href="tfind.html#tfind">tfind</a>:                        How to select a trace snapshot
<li><a accesskey="2" href="tdump.html#tdump">tdump</a>:                        How to display all data for a snapshot
<li><a accesskey="3" href="save-tracepoints.html#save-tracepoints">save tracepoints</a>:             How to save tracepoints for a future run
</ul>

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