source: chapter07/stripping.xml@ ea7ec72

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Last change on this file since ea7ec72 was ea7ec72, checked in by Bruce Dubbs <bdubbs@…>, 18 months ago

Typos.
Tweaks to stripping.xml

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