| 1 | <sect1 id="ch06-aboutdebug">
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| 2 | <title>About debugging symbols</title>
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| 3 |
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| 4 | <para>
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| 5 | Most programs and libraries by default are compiled with debugging
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| 6 | symbols and optimizing level 2 (gcc options -g and -O2) and are compiled
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| 7 | for a specific CPU. On Intel platforms software is compiled for i386
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| 8 | processors by default. If you don't wish to run software on other
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| 9 | machines other than your own, you might want to change the default
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| 10 | compiler options so that they will be compiled with a higher
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| 11 | optimization level, no debugging symbols and generate code for your
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| 12 | specific architecture. Let me first explain what debugging symbols
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| 13 | are.
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| 14 | </para>
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| 15 |
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| 16 | <para>
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| 17 | A program compiled with debugging symbols means you can run a program or
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| 18 | library through a debugger and the debugger's output will be user friendlier.
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| 19 | These debugging symbols also enlarge the program or library significantly.
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| 20 | </para>
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| 21 |
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| 22 | <para>
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| 23 | To remove debugging symbols from a binary (must be an a.out or ELF binary)
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| 24 | run <userinput>strip --strip-debug filename</userinput> You can use wild cards
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| 25 | if you need to strip debugging symbols from multiple files (use something like
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| 26 | strip --strip-debug $LFS/usr/bin/*). Another, easier, options is just
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| 27 | not to compile programs with debugging symbols. Most people will probably
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| 28 | never use a debugger on software, so by leaving those symbols out you
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| 29 | can save a lot of diskspace.
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| 30 | </para>
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| 31 |
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| 32 | <para>
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| 33 | Before you wonder if these debugging symbols would make a big difference,
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| 34 | here are some statistics:
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| 35 | </para>
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| 36 |
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| 37 | <itemizedlist>
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| 38 |
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| 39 | <listitem><para>
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| 40 | A dynamic Bash binary with debugging symbols: 1.2MB
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| 41 | </para></listitem>
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| 42 |
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| 43 | <listitem><para>
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| 44 | A dynamic Bash binary without debugging symbols: 478KB
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| 45 | </para></listitem>
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| 46 |
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| 47 | <listitem><para>
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| 48 | /lib and /usr/lib (glibc and gcc files) with debugging
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| 49 | symbols: 87MB
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| 50 | </para></listitem>
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| 51 |
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| 52 | <listitem><para>
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| 53 | /lib and /usr/lib (glibc and gcc files) without
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| 54 | debugging symbols: 16MB
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| 55 | </para></listitem>
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| 56 |
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| 57 | </itemizedlist>
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| 58 |
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| 59 | <para>
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| 60 | Sizes may vary depending on which compiler was used and which C library
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| 61 | version was used to link dynamic programs against, but your results will be
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| 62 | similar if you compare programs with and without debugging symbols. After
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| 63 | I was done with this chapter and stripped all debugging symbols from all LFS
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| 64 | binaries and libraries I regained a little over 102 MB of disk space. Quite
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| 65 | the difference.
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| 66 | </para>
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| 67 |
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| 68 | </sect1>
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| 69 |
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