| 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 (gcc option -g) Let me explain what these debugging symbols
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| 7 | are and why you may not want them.
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| 8 | </para>
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| 9 |
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| 10 | <para>
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| 11 | A program compiled with debugging symbols means a user can run a program or
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| 12 | library through a debugger and the debugger's output will be user
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| 13 | friendly. These debugging symbols also enlarge the program or library
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| 14 | significantly.
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| 15 | </para>
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| 16 |
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| 17 | <para>
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| 18 | Before you start wondering whether these debugging symbols really make a
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| 19 | big difference, here are some statistics. Use them to draw your own
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| 20 | conclusion.
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| 21 | </para>
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| 22 |
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| 23 | <itemizedlist>
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| 24 |
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| 25 | <listitem><para>
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| 26 | A dynamic Bash binary with debugging symbols: 1.2MB
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| 27 | </para></listitem>
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| 28 |
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| 29 | <listitem><para>
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| 30 | A dynamic Bash binary without debugging symbols: 478KB
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| 31 | </para></listitem>
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| 32 |
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| 33 | <listitem><para>
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| 34 | /lib and /usr/lib (glibc and gcc files) with debugging
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| 35 | symbols: 87MB
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| 36 | </para></listitem>
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| 37 |
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| 38 | <listitem><para>
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| 39 | /lib and /usr/lib (glibc and gcc files) without
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| 40 | debugging symbols: 16MB
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| 41 | </para></listitem>
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| 42 |
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| 43 | </itemizedlist>
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| 44 |
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| 45 | <para>
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| 46 | Sizes vary depending on which compiler was used and which C library
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| 47 | version was used to link dynamic programs against, but results will be
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| 48 | similar if you compare programs with and without debugging symbols. After
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| 49 | I was done with this chapter and stripped all debugging symbols from all LFS
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| 50 | binaries I regained a little over 102 MB of disk space. Quite the difference.
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| 51 | </para>
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| 52 |
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| 53 | <para>
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| 54 | To remove debugging symbols from a binary (must be an a.out or ELF
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| 55 | binary) run <userinput>strip --strip-debug filename</userinput>. Wild cards
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| 56 | can be used to strip debugging symbols from multiple files (use something
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| 57 | like <userinput>strip --strip-debug $LFS/usr/bin/*</userinput>).
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| 58 | Most people will probably never use a debugger on software, so by
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| 59 | removing those symbols a lot of disk space can be regained.
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| 60 | </para>
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| 61 |
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| 62 | <para>
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| 63 | You might find additional information in the optimization hint which can
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| 64 | be found at <ulink
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| 65 | url="http://archive.linuxfromscratch.org/lfs-hints/optimization.txt">
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| 66 | http://archive.linuxfromscratch.org/lfs-hints/optimization.txt</ulink>.
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| 67 | </para>
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| 68 |
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| 69 | </sect1>
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| 70 |
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