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<h3 class="section">E.20 Branch Trace Configuration Format</h3>
<p><a name="index-branch-trace-configuration-format-3637"></a>
For each inferior thread, <span class="sc">gdb</span> can obtain the branch trace
configuration using the &lsquo;<samp><span class="samp">qXfer:btrace-conf:read</span></samp>&rsquo;
(see <a href="qXfer-btrace_002dconf-read.html#qXfer-btrace_002dconf-read">qXfer btrace-conf read</a>) packet.
<p>The configuration describes the branch trace format and configuration
settings for that format. The following information is described:
<dl>
<dt><code>bts</code><dd>This thread uses the <dfn>Branch Trace Store</dfn> (<acronym>BTS</acronym>) format.
<dl>
<dt><code>size</code><dd>The size of the <acronym>BTS</acronym> ring buffer in bytes.
</dl>
<br><dt><code>pt</code><dd>This thread uses the <dfn>Intel Processor Trace</dfn> (<acronym>Intel
PT</acronym>) format.
<dl>
<dt><code>size</code><dd>The size of the <acronym>Intel PT</acronym> ring buffer in bytes.
</dl>
</dl>
<p><span class="sc">gdb</span> must be linked with the Expat library to support XML
branch trace configuration discovery. See <a href="Expat.html#Expat">Expat</a>.
<p>The formal DTD for the branch trace configuration format is given below:
<pre class="smallexample"> &lt;!ELEMENT btrace-conf (bts?, pt?)&gt;
&lt;!ATTLIST btrace-conf version CDATA #FIXED "1.0"&gt;
&lt;!ELEMENT bts EMPTY&gt;
&lt;!ATTLIST bts size CDATA #IMPLIED&gt;
&lt;!ELEMENT pt EMPTY&gt;
&lt;!ATTLIST pt size CDATA #IMPLIED&gt;
</pre>
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