source: BOOK/bootable/x86/kernel.xml@ 9f696e8b

clfs-3.0.0-systemd systemd
Last change on this file since 9f696e8b 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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