source: BOOK/bootable/x86/kernel.xml @ 97bc24b

clfs-2.1clfs-3.0.0-systemdclfs-3.0.0-sysvinitsystemdsysvinit
Last change on this file since 97bc24b was 97bc24b, checked in by William Harrington <kb0iic@…>, 11 years ago

Change Udev to Eudev.

  • Property mode set to 100644
File size: 9.2 KB
Line 
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-bootable-kernel" role="wrap">
9  <?dbhtml filename="kernel.html"?>
10
11  <title>Linux-&linux-version;</title>
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
39    <para os="h">Configure the kernel via a menu-driven interface.
40    Please note that the udev bootscript requires "rtc", "tmpfs" and "devtmpfs" to be
41    enabled and built into the kernel, not as modules. CBLFS has
42    some information regarding particular kernel configuration requirements of
43    packages outside of CLFS at <ulink
44    url="&cblfs-root;"/>:</para>
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    Eudev are not documented. The problem is that Eudev 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 Eudev:</para>
79
80<screen os="q"><literal>alias char-major-XXX some-module</literal></screen>
81
82    <para os="r">Because of the complications with Eudev and modules,
83    we strongly recommend starting with a completely non-modular kernel
84    configuration, especially if this is the first time using Eudev.</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="s2">Install the firmware, if the kernel configuration uses
92    them:</para>
93
94<screen os="t2"><userinput>make firmware_install</userinput></screen>
95
96    <para os="u">After kernel compilation is complete, additional steps are
97    required to complete the installation. Some files need to be copied to
98    the <filename class="directory">/boot</filename> directory.</para>
99
100    <para os="v">Issue the following command to install the kernel:</para>
101
102<screen><userinput>cp -v arch/i386/boot/bzImage /boot/vmlinuz-clfs-&linux-version;</userinput></screen>
103
104    <para os="w"><filename>System.map</filename> is a symbol file for the kernel.
105    It maps the function entry points of every function in the kernel API,
106    as well as the addresses of the kernel data structures for the running
107    kernel. Issue the following command to install the map file:</para>
108
109<screen os="w1"><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
110
111    <para os="x">The kernel configuration file <filename>.config</filename>
112    produced by the <command>make menuconfig</command> step above contains
113    all the configuration selections for the kernel that was just compiled.
114    It is a good idea to keep this file for future reference:</para>
115
116<screen os="x1"><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
117
118    <para os="y">It is important to note that the files in the kernel source
119    directory are not owned by <systemitem class="username">root</systemitem>.
120    Whenever a package is unpacked as user <systemitem
121    class="username">root</systemitem> (like we do inside the final-system
122    build environment), the files have the user and group IDs of whatever
123    they were on the packager's computer. This is usually not a problem
124    for any other package to be installed because the source tree is
125    removed after the installation. However, the Linux source tree is
126    often retained for a long time. Because of this, there is a chance
127    that whatever user ID the packager used will be assigned to somebody
128    on the machine. That person would then have write access to the kernel
129    source.</para>
130
131    <para os="y1">If the kernel source tree is going to retained, run
132    <command>chown -R 0:0</command> on the <filename
133    class="directory">linux-&linux-version;</filename> directory to
134    ensure all files are owned by user <systemitem
135    class="username">root</systemitem>.</para>
136
137    <warning os="z">
138      <para>Some kernel documentation recommends creating a symlink from
139      <filename class="symlink">/usr/src/linux</filename> pointing to the
140      kernel source directory. This is specific to kernels prior to the
141      2.6 series and <emphasis>must not</emphasis> be created on a CLFS
142      system as it can cause problems for packages you may wish to build
143      once your base CLFS system is complete.</para>
144
145      <para>Also, the headers in the system's <filename
146      class="directory">include</filename> directory should
147      <emphasis>always</emphasis> be the ones against which Glibc was
148      compiled and should <emphasis>never</emphasis> be replaced by headers
149      from a different kernel version.</para>
150    </warning>
151
152  </sect2>
153
154  <sect2 id="contents-kernel" role="content">
155    <title>Contents of Linux</title>
156
157    <segmentedlist>
158      <segtitle>Installed files</segtitle>
159      <segtitle>Installed directory</segtitle>
160
161      <seglistitem>
162        <seg>config-[linux-version], clfskernel-[linux-version],
163        and System.map-[linux-version]</seg>
164        <seg>/lib/modules</seg>
165      </seglistitem>
166    </segmentedlist>
167
168    <variablelist>
169      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
170      <?dbfo list-presentation="list"?>
171      <?dbhtml list-presentation="table"?>
172
173      <varlistentry id="config">
174        <term><filename>config-[linux-version]</filename></term>
175        <listitem>
176          <para>Contains all the configuration selections for the kernel</para>
177          <indexterm zone="ch-bootable-kernel config">
178            <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary>
179          </indexterm>
180        </listitem>
181      </varlistentry>
182
183      <varlistentry id="clfskernel">
184        <term><filename>clfskernel-[linux-version]</filename></term>
185        <listitem>
186          <para>The engine of the Linux system. When turning on the
187          computer, the kernel is the first part of the operating system
188          that gets loaded. It detects and initializes all components of
189          the computer's hardware, then makes these components available
190          as a tree of files to the software and turns a single CPU into
191          a multitasking machine capable of running scores of programs
192          seemingly at the same time.</para>
193          <indexterm zone="ch-bootable-kernel clfskernel">
194            <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary>
195          </indexterm>
196        </listitem>
197      </varlistentry>
198
199      <varlistentry id="System.map">
200        <term><filename>System.map-[linux-version]</filename></term>
201        <listitem>
202          <para>A list of addresses and symbols; it maps the entry points
203          and addresses of all the functions and data structures in the
204          kernel</para>
205          <indexterm zone="ch-bootable-kernel System.map">
206            <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary>
207          </indexterm>
208        </listitem>
209      </varlistentry>
210
211    </variablelist>
212
213  </sect2>
214
215</sect1>
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