source: chapter08/stripping.xml@ 53efe272

multilib
Last change on this file since 53efe272 was 53efe272, checked in by Thomas Trepl (Moody) <thomas@…>, 4 months ago

Automatic merge of trunk into multilib

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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="ch-system-stripping">
9 <?dbhtml filename="stripping.html"?>
10
11 <title>Stripping</title>
12
13 <para>This section is optional. If the intended user is not a
14 programmer and does not plan to do
15 any debugging on the system software, the system size can be decreased
16 by about 2 GB by removing the debugging symbols from binaries and
17 libraries. This causes no inconvenience other than not being able to
18 debug the software fully anymore.</para>
19
20 <para>Most people who use the commands mentioned below do not
21 experience any difficulties. However, it is easy to make a typo and
22 render the new system unusable, so before running the
23 <command>strip</command> commands, it is a good idea to make a
24 backup of the LFS system in its current state.</para>
25
26 <para>The debugging symbols for selected libraries are placed
27 in separate files. This debugging information is needed if running
28 regression tests that use <ulink
29 url='&blfs-book;/general/valgrind.html'>valgrind</ulink> or <ulink
30 url='&blfs-book;/general/gdb.html'>gdb</ulink> later in BLFS.
31 </para>
32
33 <para>Note that <command>strip</command> will overwrite the binary or library
34 file it is processing. This can crash the processes using code or data from
35 the file. If the process running <command>strip</command> itself is
36 affected, the binary or library being stripped can be destroyed and can
37 make the system completely unusable. To avoid it, we'll copy some libraries
38 and binaries into <filename class="directory">/tmp</filename>, strip them
39 there, and install them back with the <command>install</command> command.
40 Read the related entry in <xref linkend="pkgmgmt-upgrade-issues"/> for the
41 rationale to use the <command>install</command> command here.</para>
42
43 <note><para>The ELF loader's name is ld-linux-x86-64.so.2 on 64-bit systems
44 and ld-linux.so.2 on 32-bit systems. The construct below selects the
45 correct name for the current architecture, excluding anything ending
46 with <quote>g</quote>, in case the commands below have already been
47 run.</para></note>
48
49<!-- also of interest are libgfortan, libgo, libgomp, and libobjc from GCC -->
50
51<!--<screen><userinput>save_lib="ld-2.25.so libc-2.25.so libpthread-2.25.so libthread_db-1.0.so"-->
52<screen><userinput>save_usrlib="$(cd /usr/lib; ls ld-linux*[^g])
53 libc.so.6
54 libthread_db.so.1
55 libquadmath.so.&libquadmath-version;
56 libstdc++.so.&libstdcpp-version;
57 libitm.so.&libitm-version;
58 libatomic.so.&libatomic-version;"
59
60cd /usr/lib
61for LIB in $save_usrlib; do
62 objcopy --only-keep-debug $LIB $LIB.dbg
63 cp $LIB /tmp/$LIB
64 strip --strip-unneeded /tmp/$LIB
65 objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
66 install -vm755 /tmp/$LIB /usr/lib
67 rm /tmp/$LIB
68done</userinput>
69<userinput arch="ml_32,ml_all">
70cd /usr/lib32
71for LIB in $save_usrlib; do
72 objcopy --only-keep-debug $LIB $LIB.dbg
73 cp $LIB /tmp/$LIB
74 strip --strip-unneeded /tmp/$LIB
75 objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
76 install -vm755 /tmp/$LIB /usr/lib32
77 rm /tmp/$LIB
78done</userinput>
79<userinput arch="ml_x32,ml_all">
80cd /usr/libx32
81for LIB in $save_usrlib; do
82 objcopy --only-keep-debug $LIB $LIB.dbg
83 cp $LIB /tmp/$LIB
84 strip --strip-unneeded /tmp/$LIB
85 objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
86 install -vm755 /tmp/$LIB /usr/libx32
87 rm /tmp/$LIB
88done</userinput><userinput>
89
90online_usrbin="bash find strip"
91online_usrlib="libbfd-&binutils-version;.so
92 libhistory.so.&readline-soversion;
93 libncursesw.so.&ncurses-version;
94 libm.so.6
95 libreadline.so.&readline-soversion;
96 libz.so.&zlib-version;
97 $(cd /usr/lib; find libnss*.so* -type f)"
98
99for BIN in $online_usrbin; do
100 cp /usr/bin/$BIN /tmp/$BIN
101 strip --strip-unneeded /tmp/$BIN
102 install -vm755 /tmp/$BIN /usr/bin
103 rm /tmp/$BIN
104done
105
106for LIB in $online_usrlib; do
107 cp /usr/lib/$LIB /tmp/$LIB
108 strip --strip-unneeded /tmp/$LIB
109 install -vm755 /tmp/$LIB /usr/lib
110 rm /tmp/$LIB
111done</userinput><userinput arch="ml_32,ml_all">
112for LIB in $online_usrlib; do
113 cp /usr/lib32/$LIB /tmp/$LIB
114 strip --strip-unneeded /tmp/$LIB
115 install -vm755 /tmp/$LIB /usr/lib32
116 rm /tmp/$LIB
117done</userinput><userinput arch="ml_x32,ml_all">
118for LIB in $online_usrlib; do
119 cp /usr/libx32/$LIB /tmp/$LIB
120 strip --strip-unneeded /tmp/$LIB
121 install -vm755 /tmp/$LIB /usr/libx32
122 rm /tmp/$LIB
123done</userinput><userinput>
124
125for i in $(find /usr/lib -type f -name \*.so* ! -name \*dbg) \
126 $(find /usr/lib -type f -name \*.a) \
127 $(find /usr/{bin,sbin,libexec} -type f); do
128 case "$online_usrbin $online_usrlib $save_usrlib" in
129 *$(basename $i)* )
130 ;;
131 * ) strip --strip-unneeded $i
132 ;;
133 esac
134done</userinput><userinput arch="ml_32,ml_all">
135for i in $(find /usr/lib32 -type f -name \*.so* ! -name \*dbg); do
136 case "$online_usrbin $online_usrlib $save_usrlib" in
137 *$(basename $i)* )
138 ;;
139 * ) strip --strip-unneeded $i
140 ;;
141 esac
142done</userinput><userinput arch="ml_x32,ml_all">
143for i in $(find /usr/libx32 -type f -name \*.so* ! -name \*dbg); do
144 case "$online_usrbin $online_usrlib $save_usrlib" in
145 *$(basename $i)* )
146 ;;
147 * ) strip --strip-unneeded $i
148 ;;
149 esac
150done</userinput><userinput>
151
152unset BIN LIB save_usrlib online_usrbin online_usrlib
153</userinput></screen>
154
155 <para>A large number of files will be reported as having their file
156 format not recognized. These warnings can be safely ignored. They
157 indicate that those files are scripts instead of binaries.</para>
158
159</sect1>
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