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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. |
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| <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 |
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