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| <h3 class="section">E.18 Traceframe Info Format</h3> |
| |
| <p><a name="index-traceframe-info-format-3635"></a> |
| To be able to know which objects in the inferior can be examined when |
| inspecting a tracepoint hit, <span class="sc">gdb</span> needs to obtain the list of |
| memory ranges, registers and trace state variables that have been |
| collected in a traceframe. |
| |
| <p>This list is obtained using the ‘<samp><span class="samp">qXfer:traceframe-info:read</span></samp>’ |
| (see <a href="qXfer-traceframe-info-read.html#qXfer-traceframe-info-read">qXfer traceframe info read</a>) packet and is an XML document. |
| |
| <p><span class="sc">gdb</span> must be linked with the Expat library to support XML |
| traceframe info discovery. See <a href="Expat.html#Expat">Expat</a>. |
| |
| <p>The top-level structure of the document is shown below: |
| |
| <pre class="smallexample"> <?xml version="1.0"?> |
| <!DOCTYPE traceframe-info |
| PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN" |
| "http://sourceware.org/gdb/gdb-traceframe-info.dtd"> |
| <traceframe-info> |
| block... |
| </traceframe-info> |
| </pre> |
| <p>Each traceframe block can be either: |
| |
| <ul> |
| <li>A region of collected memory starting at <var>addr</var> and extending for |
| <var>length</var> bytes from there: |
| |
| <pre class="smallexample"> <memory start="<var>addr</var>" length="<var>length</var>"/> |
| </pre> |
| <li>A block indicating trace state variable numbered <var>number</var> has been |
| collected: |
| |
| <pre class="smallexample"> <tvar id="<var>number</var>"/> |
| </pre> |
| </ul> |
| |
| <p>The formal DTD for the traceframe info format is given below: |
| |
| <pre class="smallexample"> <!ELEMENT traceframe-info (memory | tvar)* > |
| <!ATTLIST traceframe-info version CDATA #FIXED "1.0"> |
| |
| <!ELEMENT memory EMPTY> |
| <!ATTLIST memory start CDATA #REQUIRED |
| length CDATA #REQUIRED> |
| <!ELEMENT tvar> |
| <!ATTLIST tvar id CDATA #REQUIRED> |
| </pre> |
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