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| <h2 class="appendix">Appendix F Trace File Format</h2> |
| |
| <p><a name="index-trace-file-format-2534"></a> |
| The trace file comes in three parts: a header, a textual description |
| section, and a trace frame section with binary data. |
| |
| <p>The header has the form <code>\x7fTRACE0\n</code>. The first byte is |
| <code>0x7f</code> so as to indicate that the file contains binary data, |
| while the <code>0</code> is a version number that may have different values |
| in the future. |
| |
| <p>The description section consists of multiple lines of <span class="sc">ascii</span> text |
| separated by newline characters (<code>0xa</code>). The lines may include a |
| variety of optional descriptive or context-setting information, such |
| as tracepoint definitions or register set size. <span class="sc">gdb</span> will |
| ignore any line that it does not recognize. An empty line marks the end |
| of this section. |
| |
| <!-- FIXME add some specific types of data --> |
| <p>The trace frame section consists of a number of consecutive frames. |
| Each frame begins with a two-byte tracepoint number, followed by a |
| four-byte size giving the amount of data in the frame. The data in |
| the frame consists of a number of blocks, each introduced by a |
| character indicating its type (at least register, memory, and trace |
| state variable). The data in this section is raw binary, not a |
| hexadecimal or other encoding; its endianness matches the target's |
| endianness. |
| |
| <!-- FIXME bi-arch may require endianness/arch info in description section --> |
| <dl> |
| <dt><code>R </code><var>bytes</var><dd>Register block. The number and ordering of bytes matches that of a |
| <code>g</code> packet in the remote protocol. Note that these are the |
| actual bytes, in target order and <span class="sc">gdb</span> register order, not a |
| hexadecimal encoding. |
| |
| <br><dt><code>M </code><var>address</var> <var>length</var> <var>bytes</var><code>...</code><dd>Memory block. This is a contiguous block of memory, at the 8-byte |
| address <var>address</var>, with a 2-byte length <var>length</var>, followed by |
| <var>length</var> bytes. |
| |
| <br><dt><code>V </code><var>number</var> <var>value</var><dd>Trace state variable block. This records the 8-byte signed value |
| <var>value</var> of trace state variable numbered <var>number</var>. |
| |
| </dl> |
| |
| <p>Future enhancements of the trace file format may include additional types |
| of blocks. |
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