1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2021 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with the 8Invariant Sections being "Free Software" and "Free Software Needs 9Free Documentation", with the Front-Cover Texts being "A GNU Manual," 10and with the Back-Cover Texts as in (a) below. 11 12(a) The FSF's Back-Cover Text is: "You are free to copy and modify 13this GNU Manual. 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This feature is called 77<em>MiniDebugInfo</em>. This section holds an LZMA-compressed object and 78is used to supply extra symbols for backtraces. 79</p> 80<p>The intent of this section is to provide extra minimal debugging 81information for use in simple backtraces. It is not intended to be a 82replacement for full separate debugging information (see <a href="Separate-Debug-Files.html#Separate-Debug-Files">Separate Debug Files</a>). The example below shows the intended use; however, 83<small>GDB</small> does not currently put restrictions on what sort of 84debugging information might be included in the section. 85</p> 86<p><small>GDB</small> has support for this extension. If the section exists, 87then it is used provided that no other source of debugging information 88can be found, and that <small>GDB</small> was configured with LZMA support. 89</p> 90<p>This section can be easily created using <code>objcopy</code> and other 91standard utilities: 92</p> 93<div class="smallexample"> 94<pre class="smallexample"># Extract the dynamic symbols from the main binary, there is no need 95# to also have these in the normal symbol table. 96nm -D <var>binary</var> --format=posix --defined-only \ 97 | awk '{ print $1 }' | sort > dynsyms 98 99# Extract all the text (i.e. function) symbols from the debuginfo. 100# (Note that we actually also accept "D" symbols, for the benefit 101# of platforms like PowerPC64 that use function descriptors.) 102nm <var>binary</var> --format=posix --defined-only \ 103 | awk '{ if ($2 == "T" || $2 == "t" || $2 == "D") print $1 }' \ 104 | sort > funcsyms 105 106# Keep all the function symbols not already in the dynamic symbol 107# table. 108comm -13 dynsyms funcsyms > keep_symbols 109 110# Separate full debug info into debug binary. 111objcopy --only-keep-debug <var>binary</var> debug 112 113# Copy the full debuginfo, keeping only a minimal set of symbols and 114# removing some unnecessary sections. 115objcopy -S --remove-section .gdb_index --remove-section .comment \ 116 --keep-symbols=keep_symbols debug mini_debuginfo 117 118# Drop the full debug info from the original binary. 119strip --strip-all -R .comment <var>binary</var> 120 121# Inject the compressed data into the .gnu_debugdata section of the 122# original binary. 123xz mini_debuginfo 124objcopy --add-section .gnu_debugdata=mini_debuginfo.xz <var>binary</var> 125</pre></div> 126 127<hr> 128<div class="header"> 129<p> 130Next: <a href="Index-Files.html#Index-Files" accesskey="n" rel="next">Index Files</a>, Previous: <a href="Separate-Debug-Files.html#Separate-Debug-Files" accesskey="p" rel="previous">Separate Debug Files</a>, Up: <a href="GDB-Files.html#GDB-Files" accesskey="u" rel="up">GDB Files</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> 131</div> 132 133 134 135</body> 136</html> 137