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 diskspace 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 url="http://cvs.linuxfromscratch.org/index.cgi/hints/">
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65 | http://cvs.linuxfromscratch.org/index.cgi/hints/</ulink>.
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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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