lfs-book/chapter06/aboutdebug.xml

<sect1 id="ch06-aboutdebug">
<title>About debugging symbols</title>

<para>Most programs and libraries by default are compiled with debugging
symbols (gcc option -g) Let me explain what these debugging symbols
are and why you may not want them.</para>

<para>A program compiled with debugging symbols means a user can run a program 
or library through a debugger and the debugger's output will be user
friendly. These debugging symbols also enlarge the program or library 
significantly.</para>

<para>Before you start wondering whether these debugging symbols really make a 
big difference, here are some statistics. Use them to draw your own
conclusion.</para>

<itemizedlist>

<listitem><para>A dynamic Bash binary 
with debugging symbols: 1.2MB</para></listitem>

<listitem><para>A dynamic Bash binary 
without debugging symbols: 478KB</para></listitem>

<listitem><para>/lib and /usr/lib (glibc 
and gcc files) with debugging symbols: 87MB</para></listitem>

<listitem><para>/lib and /usr/lib (glibc 
and gcc files) without debugging symbols: 16MB</para></listitem>

</itemizedlist>

<para>Sizes vary depending on which compiler was used and which C library
version was used to link dynamic programs against, but results will be
similar if you compare programs with and without debugging symbols. After
I was done with this chapter and stripped all debugging symbols from all LFS
binaries I regained a little over 102 MB of disk space. Quite the 
difference.</para>

<para>To remove debugging symbols from a binary (must be an a.out or ELF
binary) run <userinput>strip --strip-debug filename</userinput>. Wild cards
can be used to strip debugging symbols from multiple files (use something 
like <userinput>strip --strip-debug $LFS/usr/bin/*</userinput>).
Most people will probably never use a debugger on software, so by
removing those symbols a lot of disk space can be regained.</para>

<para>You might find additional information in the optimization hint which can 
be found at <ulink
url="&hint-root;optimization.txt">&hint-root;optimization.txt</ulink>
.</para>

</sect1>