source: BOOK/bootable/x86/kernel.xml@ f765af0

clfs-1.2 clfs-2.1 clfs-3.0.0-systemd clfs-3.0.0-sysvinit systemd sysvinit
Last change on this file since f765af0 was b169dfe, checked in by Chris Staub <chris@…>, 16 years ago

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[3f8be484]1<?xml version="1.0" encoding="ISO-8859-1"?>
[aa18ac0]2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
[3f8be484]4 <!ENTITY % general-entities SYSTEM "../../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="ch-bootable-kernel" role="wrap">
9 <?dbhtml filename="kernel.html"?>
10
[43daa01]11 <title>Linux-&linux-version;</title>
[3f8be484]12
13 <indexterm zone="ch-bootable-kernel">
14 <primary sortas="a-Linux">Linux</primary>
15 </indexterm>
16
17 <sect2 role="package"><title/>
18 <para>The Linux package contains the Linux kernel.</para>
19
20 </sect2>
21
22 <sect2 role="installation">
23 <title>Installation of the kernel</title>
24
25 <para os="a">Building the kernel involves a few steps&mdash;configuration,
26 compilation, and installation. Read the <filename>README</filename>
27 file in the kernel source tree for alternative methods to the way this
28 book configures the kernel.</para>
29
30 <para os="b">Prepare for compilation by running the following command:</para>
31
32<screen os="c"><userinput>make mrproper</userinput></screen>
33
34 <para os="d">This ensures that the kernel tree is absolutely clean. The
35 kernel team recommends that this command be issued prior to each
36 kernel compilation. Do not rely on the source tree being clean after
37 un-tarring.</para>
38
[77e81f1]39 <para os="h">Configure the kernel via a menu-driven interface.
40 Please note that the udev bootscript requires "rtc" and "tmpfs" to be
[0d4607d]41 enabled and built into the kernel, not as modules. CBLFS has
[3f8be484]42 some information regarding particular kernel configuration requirements of
[fb40919]43 packages outside of CLFS at <ulink
[0d4607d]44 url="&cblfs-root;"/>:</para>
[3f8be484]45
46<screen os="i"><userinput>make menuconfig</userinput></screen>
47
48 <para os="j">Alternatively, <command>make oldconfig</command> may be more
49 appropriate in some situations. See the <filename>README</filename>
50 file for more information.</para>
51
52 <para os="k">If desired, skip kernel configuration by copying the kernel
53 config file, <filename>.config</filename>, from the host system
54 (assuming it is available) to the root directory of the unpacked kernel
55 sources. However, we do not recommend this option. It is often better
56 to explore all the configuration menus and create the kernel configuration
57 from scratch.</para>
58
59 <para os="m">Compile the kernel image and modules:</para>
60
61<screen os="n"><userinput>make</userinput></screen>
62
63 <para os="o">If using kernel modules, an
64 <filename>/etc/modprobe.conf</filename> file may be needed.
65 Information pertaining to modules and kernel configuration is
66 located in the kernel documentation in the <filename
67 class="directory">Documentation</filename> directory of the kernel
68 sources tree. Also, <filename>modprobe.conf(5)</filename> may
69 be of interest.</para>
70
71 <para os="p">Be very careful when reading other documentation relating to
72 kernel modules because it usually applies to 2.4.x kernels only. As
73 far as we know, kernel configuration issues specific to Hotplug and
74 Udev are not documented. The problem is that Udev will create a device
75 node only if Hotplug or a user-written script inserts the corresponding
76 module into the kernel, and not all modules are detectable by Hotplug.
77 Note that statements like the one below in the
78 <filename>/etc/modprobe.conf</filename> file do not work with Udev:</para>
79
80<screen os="q"><literal>alias char-major-XXX some-module</literal></screen>
81
[5d9d2e5]82 <para os="r">Because of the complications with Udev and modules,
[3f8be484]83 we strongly recommend starting with a completely non-modular kernel
84 configuration, especially if this is the first time using Udev.</para>
85
86 <para os="s">Install the modules, if the kernel configuration uses
87 them:</para>
88
89<screen os="t"><userinput>make modules_install</userinput></screen>
90
91 <para os="u">After kernel compilation is complete, additional steps are
92 required to complete the installation. Some files need to be copied to
93 the <filename class="directory">/boot</filename> directory.</para>
94
95 <para os="v">Issue the following command to install the kernel:</para>
96
[e51ba26]97<screen><userinput>cp -v arch/i386/boot/bzImage /boot/clfskernel-&linux-version;</userinput></screen>
[3f8be484]98
99 <para os="w"><filename>System.map</filename> is a symbol file for the kernel.
100 It maps the function entry points of every function in the kernel API,
101 as well as the addresses of the kernel data structures for the running
102 kernel. Issue the following command to install the map file:</para>
103
[e51ba26]104<screen os="w1"><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
[3f8be484]105
106 <para os="x">The kernel configuration file <filename>.config</filename>
107 produced by the <command>make menuconfig</command> step above contains
108 all the configuration selections for the kernel that was just compiled.
109 It is a good idea to keep this file for future reference:</para>
110
[e51ba26]111<screen os="x1"><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
[3f8be484]112
113 <para os="y">It is important to note that the files in the kernel source
114 directory are not owned by <systemitem class="username">root</systemitem>.
115 Whenever a package is unpacked as user <systemitem
[a7fa075]116 class="username">root</systemitem> (like we do inside the final-system
117 build environment), the files have the user and group IDs of whatever
[3f8be484]118 they were on the packager's computer. This is usually not a problem
119 for any other package to be installed because the source tree is
120 removed after the installation. However, the Linux source tree is
[a7fa075]121 often retained for a long time. Because of this, there is a chance
[3f8be484]122 that whatever user ID the packager used will be assigned to somebody
123 on the machine. That person would then have write access to the kernel
124 source.</para>
125
[43daa01]126 <para os="y1">If the kernel source tree is going to retained, run
[3f8be484]127 <command>chown -R 0:0</command> on the <filename
[43daa01]128 class="directory">linux-&linux-version;</filename> directory to
[3f8be484]129 ensure all files are owned by user <systemitem
130 class="username">root</systemitem>.</para>
131
132 <warning os="z">
133 <para>Some kernel documentation recommends creating a symlink from
134 <filename class="symlink">/usr/src/linux</filename> pointing to the
135 kernel source directory. This is specific to kernels prior to the
[fb40919]136 2.6 series and <emphasis>must not</emphasis> be created on a CLFS
[3f8be484]137 system as it can cause problems for packages you may wish to build
[fb40919]138 once your base CLFS system is complete.</para>
[3f8be484]139
140 <para>Also, the headers in the system's <filename
141 class="directory">include</filename> directory should
142 <emphasis>always</emphasis> be the ones against which Glibc was
[b169dfe]143 compiled and should <emphasis>never</emphasis> be replaced by headers
144 from a different kernel version.</para>
[3f8be484]145 </warning>
146
147 </sect2>
148
149 <sect2 id="contents-kernel" role="content">
150 <title>Contents of Linux</title>
151
152 <segmentedlist>
153 <segtitle>Installed files</segtitle>
154
155 <seglistitem>
[3f76cac]156 <seg>config-[linux-version], clfskernel-[linux-version],
[3f8be484]157 and System.map-[linux-version]</seg>
158 </seglistitem>
159 </segmentedlist>
160
161 <variablelist>
162 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
163 <?dbfo list-presentation="list"?>
164 <?dbhtml list-presentation="table"?>
165
166 <varlistentry id="config">
167 <term><filename>config-[linux-version]</filename></term>
168 <listitem>
169 <para>Contains all the configuration selections for the kernel</para>
170 <indexterm zone="ch-bootable-kernel config">
171 <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary>
172 </indexterm>
173 </listitem>
174 </varlistentry>
175
[3f76cac]176 <varlistentry id="clfskernel">
177 <term><filename>clfskernel-[linux-version]</filename></term>
[3f8be484]178 <listitem>
179 <para>The engine of the Linux system. When turning on the
180 computer, the kernel is the first part of the operating system
181 that gets loaded. It detects and initializes all components of
182 the computer's hardware, then makes these components available
183 as a tree of files to the software and turns a single CPU into
184 a multitasking machine capable of running scores of programs
185 seemingly at the same time.</para>
[3f76cac]186 <indexterm zone="ch-bootable-kernel clfskernel">
187 <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary>
[3f8be484]188 </indexterm>
189 </listitem>
190 </varlistentry>
191
192 <varlistentry id="System.map">
193 <term><filename>System.map-[linux-version]</filename></term>
194 <listitem>
195 <para>A list of addresses and symbols; it maps the entry points
196 and addresses of all the functions and data structures in the
197 kernel</para>
198 <indexterm zone="ch-bootable-kernel System.map">
199 <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary>
200 </indexterm>
201 </listitem>
202 </varlistentry>
203
204 </variablelist>
205
206 </sect2>
207
208</sect1>
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