<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- Copyright (C) 1988-2019 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Free Software" and "Free Software Needs Free Documentation", with the Front-Cover Texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. (a) The FSF's Back-Cover Text is: "You are free to copy and modify this GNU Manual. Buying copies from GNU Press supports the FSF in developing GNU and promoting software freedom." --> <!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ --> <head> <title>Trace File Format (Debugging with GDB)</title> <meta name="description" content="Trace File Format (Debugging with GDB)"> <meta name="keywords" content="Trace File Format (Debugging with GDB)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <link href="index.html#Top" rel="start" title="Top"> <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> <link href="index.html#Top" rel="up" title="Top"> <link href="Index-Section-Format.html#Index-Section-Format" rel="next" title="Index Section Format"> <link href="Process-list.html#Process-list" rel="prev" title="Process list"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} blockquote.smallquotation {font-size: smaller} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} div.lisp {margin-left: 3.2em} div.smalldisplay {margin-left: 3.2em} div.smallexample {margin-left: 3.2em} div.smalllisp {margin-left: 3.2em} kbd {font-style: oblique} pre.display {font-family: inherit} pre.format {font-family: inherit} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} pre.smalldisplay {font-family: inherit; font-size: smaller} pre.smallexample {font-size: smaller} pre.smallformat {font-family: inherit; font-size: smaller} pre.smalllisp {font-size: smaller} span.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} ul.no-bullet {list-style: none} --> </style> </head> <body lang="en"> <a name="Trace-File-Format"></a> <div class="header"> <p> Next: <a href="Index-Section-Format.html#Index-Section-Format" accesskey="n" rel="next">Index Section Format</a>, Previous: <a href="Operating-System-Information.html#Operating-System-Information" accesskey="p" rel="prev">Operating System Information</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> </div> <hr> <a name="Trace-File-Format-1"></a> <h2 class="appendix">Appendix I Trace File Format</h2> <a name="index-trace-file-format"></a> <p>The trace file comes in three parts: a header, a textual description section, and a trace frame section with binary data. </p> <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> <p>The description section consists of multiple lines of <small>ASCII</small> 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. <small>GDB</small> will ignore any line that it does not recognize. An empty line marks the end of this section. </p> <dl compact="compact"> <dt><code>R <var>size</var></code></dt> <dd><p>Specifies the size of a register block in bytes. This is equal to the size of a <code>g</code> packet payload in the remote protocol. <var>size</var> is an ascii decimal number. There should be only one such line in a single trace file. </p> </dd> <dt><code>status <var>status</var></code></dt> <dd><p>Trace status. <var>status</var> has the same format as a <code>qTStatus</code> remote packet reply. There should be only one such line in a single trace file. </p> </dd> <dt><code>tp <var>payload</var></code></dt> <dd><p>Tracepoint definition. The <var>payload</var> has the same format as <code>qTfP</code>/<code>qTsP</code> remote packet reply payload. A single tracepoint may take multiple lines of definition, corresponding to the multiple reply packets. </p> </dd> <dt><code>tsv <var>payload</var></code></dt> <dd><p>Trace state variable definition. The <var>payload</var> has the same format as <code>qTfV</code>/<code>qTsV</code> remote packet reply payload. A single variable may take multiple lines of definition, corresponding to the multiple reply packets. </p> </dd> <dt><code>tdesc <var>payload</var></code></dt> <dd><p>Target description in XML format. The <var>payload</var> is a single line of the XML file. All such lines should be concatenated together to get the original XML file. This file is in the same format as <code>qXfer</code> <code>features</code> payload, and corresponds to the main <code>target.xml</code> file. Includes are not allowed. </p> </dd> </dl> <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. </p> <dl compact="compact"> <dt><code>R <var>bytes</var></code></dt> <dd><p>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, not a hexadecimal encoding. </p> </dd> <dt><code>M <var>address</var> <var>length</var> <var>bytes</var>...</code></dt> <dd><p>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. </p> </dd> <dt><code>V <var>number</var> <var>value</var></code></dt> <dd><p>Trace state variable block. This records the 8-byte signed value <var>value</var> of trace state variable numbered <var>number</var>. </p> </dd> </dl> <p>Future enhancements of the trace file format may include additional types of blocks. </p> <hr> <div class="header"> <p> Next: <a href="Index-Section-Format.html#Index-Section-Format" accesskey="n" rel="next">Index Section Format</a>, Previous: <a href="Operating-System-Information.html#Operating-System-Information" accesskey="p" rel="prev">Operating System Information</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> </div> </body> </html>