[7152faa] | 1 | <?xml version="1.0" encoding="UTF-8"?>
|
---|
[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
---|
| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
|
---|
[81fd230] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
|
---|
| 5 | %general-entities;
|
---|
| 6 | ]>
|
---|
[ddd5542] | 7 |
|
---|
[8a269ec] | 8 | <sect1 id="ch-system-stripping">
|
---|
| 9 | <?dbhtml filename="stripping.html"?>
|
---|
[ddd5542] | 10 |
|
---|
[8a269ec] | 11 | <title>Stripping</title>
|
---|
[ddd5542] | 12 |
|
---|
[d672ab7] | 13 | <para>This section is optional. If the intended user is not a
|
---|
[c32384e] | 14 | programmer and does not plan to do
|
---|
[9c753b58] | 15 | any debugging of the system software, the system's size can be decreased
|
---|
| 16 | by some 2 GB by removing the debugging symbols, and some unnecessary symbol table
|
---|
| 17 | entries, from binaries and libraries. This causes no real inconvenience for
|
---|
| 18 | a typical Linux user.</para>
|
---|
[ddd5542] | 19 |
|
---|
[826bbcc] | 20 | <para>Most people who use the commands mentioned below do not
|
---|
[9c753b58] | 21 | experience any difficulties. However, it is easy to make a mistake and
|
---|
| 22 | render the new system unusable. So before running the
|
---|
[826bbcc] | 23 | <command>strip</command> commands, it is a good idea to make a
|
---|
[ddd5542] | 24 | backup of the LFS system in its current state.</para>
|
---|
| 25 |
|
---|
[9c753b58] | 26 | <para>A <command>strip</command> command with the
|
---|
[942e81de] | 27 | <parameter>--strip-unneeded</parameter> option removes all debug symbols
|
---|
[9c753b58] | 28 | from a binary or library. It also removes all symbol table entries not
|
---|
[942e81de] | 29 | needed by the linker (for static libraries) or dynamic linker (for
|
---|
[9c753b58] | 30 | dynamically linked binaries and shared libraries).</para>
|
---|
[942e81de] | 31 |
|
---|
[80da60f] | 32 | <!-- TODO: Zstd is better than Zlib for both speed and size.
|
---|
| 33 | Unfortunately Valgrind does not support Zstd-compressed debug
|
---|
| 34 | info yet: https://bugs.kde.org/show_bug.cgi?id=469782 -->
|
---|
| 35 | <para>The debugging symbols from selected libraries are compressed with
|
---|
| 36 | <application>Zlib</application> and preserved in separate files. That
|
---|
| 37 | debugging information is needed to run regression tests with <ulink
|
---|
[d672ab7] | 38 | url='&blfs-book;/general/valgrind.html'>valgrind</ulink> or <ulink
|
---|
[9c753b58] | 39 | url='&blfs-book;/general/gdb.html'>gdb</ulink> later, in BLFS.
|
---|
[c32384e] | 40 | </para>
|
---|
[6c8a79a] | 41 |
|
---|
[11d5dee] | 42 | <para>Note that <command>strip</command> will overwrite the binary or library
|
---|
[8a269ec] | 43 | file it is processing. This can crash the processes using code or data from
|
---|
[9c753b58] | 44 | the file. If the process running <command>strip</command> is
|
---|
| 45 | affected, the binary or library being stripped can be destroyed; this can
|
---|
| 46 | make the system completely unusable. To avoid this problem we copy some libraries
|
---|
[11d5dee] | 47 | and binaries into <filename class="directory">/tmp</filename>, strip them
|
---|
[9c753b58] | 48 | there, then reinstall them with the <command>install</command> command.
|
---|
| 49 | (The related entry in <xref linkend="pkgmgmt-upgrade-issues"/> gives the
|
---|
| 50 | rationale for using the <command>install</command> command here.)</para>
|
---|
[de28837] | 51 |
|
---|
[a3d6232] | 52 | <note><para>The ELF loader's name is ld-linux-x86-64.so.2 on 64-bit systems
|
---|
[bcb20b4] | 53 | and ld-linux.so.2 on 32-bit systems. The construct below selects the
|
---|
[8731bd1] | 54 | correct name for the current architecture, excluding anything ending
|
---|
[ee950a5e] | 55 | with <literal>g</literal>, in case the commands below have already been
|
---|
[8731bd1] | 56 | run.</para></note>
|
---|
[4350669] | 57 |
|
---|
[b595526] | 58 | <important>
|
---|
| 59 | <para>
|
---|
[04038ad] | 60 | If there is any package whose version is different from the version
|
---|
[b595526] | 61 | specified by the book (either following a security advisory or
|
---|
| 62 | satisfying personal preference), it may be necessary to update the
|
---|
[04038ad] | 63 | library file name in <envar>save_usrlib</envar> or
|
---|
[b595526] | 64 | <envar>online_usrlib</envar>.
|
---|
| 65 | <emphasis role='bold'>Failing to do so may render the system
|
---|
| 66 | completely unusable.</emphasis>
|
---|
| 67 | </para>
|
---|
| 68 | </important>
|
---|
| 69 |
|
---|
[77d2cd8d] | 70 | <!-- also of interest are libgfortan, libgo, libgomp, and libobjc from GCC -->
|
---|
[6c8a79a] | 71 |
|
---|
[00abb8f] | 72 | <!--<screen><userinput>save_lib="ld-2.25.so libc-2.25.so libpthread-2.25.so libthread_db-1.0.so"-->
|
---|
[8731bd1] | 73 | <screen><userinput>save_usrlib="$(cd /usr/lib; ls ld-linux*[^g])
|
---|
[adcaf07e] | 74 | libc.so.6
|
---|
[6094dae] | 75 | libthread_db.so.1
|
---|
[d672ab7] | 76 | libquadmath.so.&libquadmath-version;
|
---|
[6094dae] | 77 | libstdc++.so.&libstdcpp-version;
|
---|
[d672ab7] | 78 | libitm.so.&libitm-version;
|
---|
| 79 | libatomic.so.&libatomic-version;"
|
---|
[c32384e] | 80 |
|
---|
| 81 | cd /usr/lib
|
---|
| 82 |
|
---|
| 83 | for LIB in $save_usrlib; do
|
---|
[80da60f] | 84 | objcopy --only-keep-debug --compress-debug-sections=zlib $LIB $LIB.dbg
|
---|
[ff96923] | 85 | cp $LIB /tmp/$LIB
|
---|
| 86 | strip --strip-unneeded /tmp/$LIB
|
---|
| 87 | objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
|
---|
| 88 | install -vm755 /tmp/$LIB /usr/lib
|
---|
| 89 | rm /tmp/$LIB
|
---|
[c32384e] | 90 | done
|
---|
| 91 |
|
---|
[de28837] | 92 | online_usrbin="bash find strip"
|
---|
[6094dae] | 93 | online_usrlib="libbfd-&binutils-version;.so
|
---|
[be5b2e0] | 94 | libsframe.so.&libsframe-version;
|
---|
[b83366b] | 95 | libhistory.so.&readline-soversion;
|
---|
[6094dae] | 96 | libncursesw.so.&ncurses-version;
|
---|
| 97 | libm.so.6
|
---|
[b83366b] | 98 | libreadline.so.&readline-soversion;
|
---|
[6094dae] | 99 | libz.so.&zlib-version;
|
---|
[b1b9182] | 100 | libzstd.so.&zstd-version;
|
---|
[d1592b9] | 101 | $(cd /usr/lib; find libnss*.so* -type f)"
|
---|
[de28837] | 102 |
|
---|
| 103 | for BIN in $online_usrbin; do
|
---|
| 104 | cp /usr/bin/$BIN /tmp/$BIN
|
---|
[08f72423] | 105 | strip --strip-unneeded /tmp/$BIN
|
---|
[de28837] | 106 | install -vm755 /tmp/$BIN /usr/bin
|
---|
| 107 | rm /tmp/$BIN
|
---|
| 108 | done
|
---|
[6c8a79a] | 109 |
|
---|
[de28837] | 110 | for LIB in $online_usrlib; do
|
---|
| 111 | cp /usr/lib/$LIB /tmp/$LIB
|
---|
| 112 | strip --strip-unneeded /tmp/$LIB
|
---|
| 113 | install -vm755 /tmp/$LIB /usr/lib
|
---|
| 114 | rm /tmp/$LIB
|
---|
| 115 | done
|
---|
[658dcab] | 116 |
|
---|
[08f72423] | 117 | for i in $(find /usr/lib -type f -name \*.so* ! -name \*dbg) \
|
---|
| 118 | $(find /usr/lib -type f -name \*.a) \
|
---|
| 119 | $(find /usr/{bin,sbin,libexec} -type f); do
|
---|
| 120 | case "$online_usrbin $online_usrlib $save_usrlib" in
|
---|
[d672ab7] | 121 | *$(basename $i)* )
|
---|
[11d5dee] | 122 | ;;
|
---|
[d672ab7] | 123 | * ) strip --strip-unneeded $i
|
---|
[11d5dee] | 124 | ;;
|
---|
[de28837] | 125 | esac
|
---|
| 126 | done
|
---|
| 127 |
|
---|
| 128 | unset BIN LIB save_usrlib online_usrbin online_usrlib
|
---|
| 129 | </userinput></screen>
|
---|
[3c928f1] | 130 |
|
---|
[9c753b58] | 131 | <para>A large number of files will be flagged as errors because their file
|
---|
| 132 | format is not recognized. These warnings can be safely ignored. They
|
---|
| 133 | indicate that those files are scripts, not binaries.</para>
|
---|
[6c8a79a] | 134 |
|
---|
[3c928f1] | 135 | </sect1>
|
---|