lfs-book/chapter06/strippingagain.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
]>

<sect1 id="ch-system-strippingagain">
  <?dbhtml filename="strippingagain.html"?>

  <title>Stripping Again</title>

  <para>This section is optional.  If the intended user is not a 
  programmer and does not plan to do
  any debugging on the system software, the system size can be decreased
  by about 90 MB by removing the debugging symbols from binaries and
  libraries. This causes no inconvenience other than not being able to
  debug the software fully anymore.</para>

  <para>Most people who use the commands mentioned below do not
  experience any difficulties. However, it is easy to make a typo and
  render the new system unusable, so before running the
  <command>strip</command> commands, it is a good idea to make a
  backup of the LFS system in its current state.</para>

  <para>First place the debugging symbols for selected libraries 
  in separate files.  This debugging information is needed if running 
  regression tests that use <ulink 
  url='&blfs-book;/general/valgrind.html'>valgrind</ulink> or <ulink 
  url='&blfs-book;/general/gdb.html'>gdb</ulink> later in BLFS.
  </para>

<!-- also of interest are libgfortan, libgo, libgomp, and libobjc from gcc -->

<!--<screen><userinput>save_lib="ld-2.25.so libc-2.25.so libpthread-2.25.so libthread_db-1.0.so"-->
<screen><userinput>save_lib="ld-&glibc-version;.so libc-&glibc-version;.so libpthread-&glibc-version;.so libthread_db-&libthread_db-version;.so"

cd /lib

for LIB in $save_lib; do
    objcopy --only-keep-debug $LIB $LIB.dbg 
    strip --strip-unneeded $LIB
    objcopy --add-gnu-debuglink=$LIB.dbg $LIB 
done    

save_usrlib="libquadmath.so.&libquadmath-version; libstdc++.so.&libstdcpp-version;
             libmpx.so.&libmpx-version; libmpxwrappers.so.&libmpxwrap-version; libitm.so.&libitm-version;
             libcilkrts.so.&libcilkrts-version; libatomic.so.&libatomic-version;"

cd /usr/lib

for LIB in $save_usrlib; do
    objcopy --only-keep-debug $LIB $LIB.dbg
    strip --strip-unneeded $LIB
    objcopy --add-gnu-debuglink=$LIB.dbg $LIB
done

unset LIB save_lib save_usrlib</userinput></screen>

  <para>Before performing the stripping, take special care to ensure that
  none of the binaries that are about to be stripped are running. If
  unsure whether the user entered chroot with the command given in
  <xref linkend="ch-system-chroot" role=","/> first exit from
  chroot:</para>

<screen role="nodump"><userinput>logout</userinput></screen>

  <para>Then reenter it with:</para>

<screen role="nodump"><userinput>chroot $LFS /tools/bin/env -i            \
    HOME=/root TERM=$TERM PS1='\u:\w\$ ' \
    PATH=/bin:/usr/bin:/sbin:/usr/sbin   \
    /tools/bin/bash --login</userinput></screen>

  <para>Now the binaries and libraries can be safely stripped:</para>

<screen><userinput>/tools/bin/find /usr/lib -type f -name \*.a \
   -exec /tools/bin/strip --strip-debug {} ';'

/tools/bin/find /lib /usr/lib -type f \( -name \*.so* -a ! -name \*dbg \) \
   -exec /tools/bin/strip --strip-unneeded {} ';'

/tools/bin/find /{bin,sbin} /usr/{bin,sbin,libexec} -type f \
    -exec /tools/bin/strip --strip-all {} ';'</userinput></screen>

  <para>A large number of files will be reported as having their file
  format not recognized. These warnings can be safely ignored. These
  warnings indicate that those files are scripts instead of
  binaries.</para>

</sect1>