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="http://archive.linuxfromscratch.org/lfs-hints/optimization.txt">
http://archive.linuxfromscratch.org/lfs-hints/optimization.txt</ulink>.
</para>

</sect1>