lfs-book/chapter06/aboutdebug.xml

<sect1 id="ch06-aboutdebug">
<title>About debugging symbols</title>
<?dbhtml filename="aboutdebug.html" dir="chapter06"?>

<para>Most programs and libraries by default are compiled with debugging
symbols (gcc option -g).</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: 1.2 MB</para></listitem>

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

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

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

<para>To remove debugging symbols from a binary (must be an a.out or ELF
binary) run <userinput>strip --strip-debug filename</userinput>. Wildcards
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>For your convenience, chapter 9 includes one simple command to strip
all debugging symbols from all programs and libraries on your
system. If you are short on diskspace you can start with stripping
all the files under <filename class="directory">$LFS/static</filename></para>

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

</sect1>