source: chapter07/stripping.xml@ 6c329d7

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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-tools-stripping">
9 <?dbhtml filename="stripping.html"?>
10
11 <title>Cleaning up and Saving the Temporary System</title>
12
13 <para>The libtool .la files are only useful when linking with static
14 libraries. They are unneeded, and potentially harmful, when using dynamic
15 shared libraries, specially when using non-autotools build systems.
16 While still in chroot, remove those files now:</para>
17
18<screen role="nodump"><userinput>find /usr/{lib,libexec} -name \*.la -delete</userinput></screen>
19
20 <note><para>
21 All the remaining steps in this section are optional. Nevertheless,
22 as soon as you begin installing packages in <xref
23 linkend="chapter-building-system"/>, the temporary tools will be
24 overwritten. So it may be a good idea to do a backup of the temporary
25 tools as described below. The other steps are only needed if you are
26 really short on disk space.
27 </para></note>
28
29 <para>
30 The following steps are performed from outside the chroot
31 environment. That means, you have to leave the chroot environment
32 first before continuing. The reason for that is to:
33 <itemizedlist>
34 <listitem>
35 <para>
36 make sure that objects are not in use while they are
37 manipulated.
38 </para>
39 </listitem>
40 <listitem>
41 <para>
42 get access to file system locations outside of the chroot
43 environment to store/read the backup archive which should
44 not be placed within the
45 <filename class="directory">$LFS</filename> hierarchy for
46 safety reasons.
47 </para>
48 </listitem>
49 </itemizedlist>
50 </para>
51
52 <para>
53 Leave the chroot environment and unmount the kernel virtual file
54 systems:
55 </para>
56
57 <note>
58 <para>All of the following instructions are executed by
59 <systemitem class="username">root</systemitem>. Take extra
60 care about the commands you're going to run as mistakes
61 here can modify your host system. Be aware that the
62 environment variable <envar>LFS</envar> is set for user
63 <systemitem class="username">lfs</systemitem> by default
64 but it might <emphasis>not</emphasis> be set for
65 <systemitem class="username">root</systemitem>. Whenever
66 commands are to be executed by <systemitem class="username">root</systemitem>,
67 make sure you have set <envar>LFS</envar> accordingly.
68 This has been discussed in <xref linkend='ch-partitioning-aboutlfs'/>.
69 </para>
70 </note>
71
72<screen role="nodump"><userinput>exit
73umount $LFS/dev{/pts,}
74umount $LFS/{sys,proc,run}</userinput></screen>
75
76 <sect2>
77 <title>Stripping</title>
78
79 <para>If the LFS partition is rather small, it is good to
80 know that unnecessary items can be removed. The executables and
81 libraries built so far contain a little over 90 MB of unneeded debugging
82 symbols.</para>
83
84 <para>Strip off debugging symbols from binaries:</para>
85<screen role="nodump"><userinput>strip --strip-debug $LFS/usr/lib/*
86strip --strip-unneeded $LFS/usr/{,s}bin/*
87strip --strip-unneeded $LFS/tools/bin/*</userinput></screen>
88
89 <para>These commands will skip a number of files reporting that it does not
90 recognize their file format. Most of these are scripts instead of binaries.
91 <!--Note that we use the <command>strip</command> program built in
92 <quote>Binutils pass 2</quote>, since it is the one that knows how to strip
93 our cross-compiled programs.--></para>
94
95 <para>Take care <emphasis>NOT</emphasis> to use
96 <parameter>--strip-unneeded</parameter> on the libraries. The static
97 ones would be destroyed and the toolchain packages would need to be
98 built all over again.</para>
99
100 <para>To save more space (slightly more than 35 MB), remove the documentation:</para>
101
102<screen role="nodump"><userinput>rm -rf $LFS/usr/share/{info,man,doc}</userinput></screen>
103
104 <para>At this point, you should have at least 5 GB of free space on the
105 chroot partition that can be used to build and install Glibc and GCC in
106 the next phase. If you can build and install Glibc, you can build and install
107 the rest too. You can check the free disk space with the command
108 <command>df -h $LFS</command>.</para>
109
110 </sect2>
111
112 <sect2>
113 <title>Backup</title>
114
115 <para>
116 Now that the essential tools have been created, its time to think about
117 a backup. When every check has passed successfully in the previously
118 built packages, your temporary tools are in a good state and might be
119 backed up for later reuse. In case of fatal failures in the subsequent
120 chapters, it often turns out that removing everything and starting over
121 (more carefully) is the best option to recover. Unfortunately, all the
122 temporary tools will be removed, too. To avoid spending extra time to
123 redo something which has been built successfully, prepare a backup.
124 </para>
125
126 <para>
127 Make sure you have at least 600 MB free disk space (the source tarballs
128 will be included in the backup archive) in the home directory of user
129 <systemitem class="username">root</systemitem>.
130 </para>
131
132 <para>
133 Create the backup archive by running the following command:
134 </para>
135
136<screen role="nodump" revision="sysv"><userinput>cd $LFS &amp;&amp;
137tar -cJpf $HOME/lfs-temp-tools-&version;.tar.xz .</userinput></screen>
138
139<screen role="nodump" revision="systemd"><userinput>cd $LFS &amp;&amp;
140tar -cJpf $HOME/lfs-temp-tools-&versiond;.tar.xz .</userinput></screen>
141
142 <para>
143 Replace <envar>$HOME</envar> by a directory of your choice if you
144 do not want to have the backup stored in <systemitem
145 class="username">root</systemitem>'s home directory.
146 </para>
147 </sect2>
148
149 <sect2>
150 <title>Restore</title>
151
152 <para>
153 In case some mistakes have been made and you need to start over, you can
154 use this backup to restore the temporary tools and save some recovery time.
155 Since the sources are located under
156 <filename class="directory">$LFS</filename>, they are included in the
157 backup archive as well, so they do not need to be downloaded again. After
158 checking that <envar>$LFS</envar> is set properly,
159 restore the backup by executing the following commands:
160 </para>
161
162<!-- Make the following look different so users don't blindly run the
163 restore when they don't need to. -->
164
165<screen role="nodump" revision="sysv"><computeroutput>cd $LFS &amp;&amp;
166rm -rf ./* &amp;&amp;
167tar -xpf $HOME/lfs-temp-tools-&version;.tar.xz</computeroutput></screen>
168
169<screen role="nodump" revision="systemd"><computeroutput>cd $LFS &amp;&amp;
170rm -rf ./* &amp;&amp;
171tar -xpf $HOME/lfs-temp-tools-&versiond;.tar.xz</computeroutput></screen>
172
173 <para>
174 Again, double check that the environment has been setup properly
175 and continue building the rest of the system.
176 </para>
177
178 <important>
179 <para>
180 If you left the chroot environment either to strip off debug
181 symbols, create a backup, or restart building using a restore,
182 remember to mount the kernel virtual filesystems now again as
183 described in <xref linkend='ch-tools-kernfs'/> and re-enter
184 the chroot environment (see <xref linkend='ch-tools-chroot'/>)
185 again before continuing.
186 </para>
187 </important>
188
189 </sect2>
190
191</sect1>
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