diff options
Diffstat (limited to 'chapter08/stripping.xml')
| -rw-r--r-- | chapter08/stripping.xml | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/chapter08/stripping.xml b/chapter08/stripping.xml new file mode 100644 index 000000000..853ea8848 --- /dev/null +++ b/chapter08/stripping.xml @@ -0,0 +1,110 @@ +<?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-stripping"> + <?dbhtml filename="stripping.html"?> + + <title>Stripping</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 2 GB 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>The debugging symbols for selected libraries are placed + 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> + + <para>Note that <command>strip</command> will overwrite the binary or library + file it is processing. This can crash the processes using code or data from + the file. If the process running <command>strip</command> itself is + affected, the binary or library being stripped can be destroyed and can + make the system completely unusable. To avoid it, we'll copy some libraries + and binaries into <filename class="directory">/tmp</filename>, strip them + there, and install them back with the <command>install</command> command. + Read the related entry in <xref linkend="pkgmgmt-upgrade-issues"/> for the + rationale to use the <command>install</command> command here.</para> + + <note><para>The ELF loader's name is ld-linux-x86-64.so.2 on 64-bit systems + and ld-linux.so.2 on 32-bit systems. The contruct below selects the + correct name for the current architecture.</para></note> + +<!-- 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_usrlib="$(cd /usr/lib; ls ld_linux*) + libc.so.6 + libthread_db.so.1 + libquadmath.so.&libquadmath-version; + libstdc++.so.&libstdcpp-version; + libitm.so.&libitm-version; + libatomic.so.&libatomic-version;" + +cd /usr/lib + +for LIB in $save_usrlib; do + objcopy --only-keep-debug $LIB $LIB.dbg + cp $LIB /tmp/$LIB + strip --strip-unneeded /tmp/$LIB + objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB + install -vm755 /tmp/$LIB /usr/lib + rm /tmp/$LIB +done + +online_usrbin="bash find strip" +online_usrlib="libbfd-&binutils-version;.so + libhistory.so.&readline-version; + libncursesw.so.&ncurses-version; + libm.so.6 + libreadline.so.&readline-version; + libz.so.&zlib-version; + $(cd /usr/lib; find libnss*.so* -type f)" + +for BIN in $online_usrbin; do + cp /usr/bin/$BIN /tmp/$BIN + strip --strip-unneeded /tmp/$BIN + install -vm755 /tmp/$BIN /usr/bin + rm /tmp/$BIN +done + +for LIB in $online_usrlib; do + cp /usr/lib/$LIB /tmp/$LIB + strip --strip-unneeded /tmp/$LIB + install -vm755 /tmp/$LIB /usr/lib + rm /tmp/$LIB +done + +for i in $(find /usr/lib -type f -name \*.so* ! -name \*dbg) \ + $(find /usr/lib -type f -name \*.a) \ + $(find /usr/{bin,sbin,libexec} -type f); do + case "$online_usrbin $online_usrlib $save_usrlib" in + *$(basename $i)* ) + ;; + * ) strip --strip-unneeded $i + ;; + esac +done + +unset BIN LIB save_usrlib online_usrbin online_usrlib +</userinput></screen> + + <para>A large number of files will be reported as having their file + format not recognized. These warnings can be safely ignored. They + indicate that those files are scripts instead of binaries.</para> + +</sect1> |