source: BOOK/bootable/x86/kernel.xml @ fb40919

Last change on this file since fb40919 was fb40919, checked in by Chris Staub <chris@…>, 13 years ago

Changed many 'LFS' references to 'CLFS'

  • Property mode set to 100644
File size: 9.4 KB
1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
3  "" [
4  <!ENTITY % general-entities SYSTEM "../../general.ent">
5  %general-entities;
8<sect1 id="ch-bootable-kernel" role="wrap">
9  <?dbhtml filename="kernel.html"?>
11  <title>Linux-&linux-version;</title>
13  <indexterm zone="ch-bootable-kernel">
14    <primary sortas="a-Linux">Linux</primary>
15  </indexterm>
17  <sect2 role="package"><title/>
18    <para>The Linux package contains the Linux kernel.</para>
20  </sect2>
22  <sect2 role="installation">
23    <title>Installation of the kernel</title>
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>
30    <para os="b">Prepare for compilation by running the following command:</para>
32<screen os="c"><userinput>make mrproper</userinput></screen>
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>
39    <para os="e">If, in <xref linkend="ch-scripts-console" role=","/> it was
40    decided to compile the keymap into the kernel, issue the command
41    below:</para>
43<screen os="f"><userinput>loadkeys -m /usr/share/kbd/keymaps/<replaceable>[path to  keymap]</replaceable> &gt; \
44    drivers/char/defkeymap.c</userinput></screen>
46    <para os="g">For example, if using a Dutch keyboard, use
47    <filename>/usr/share/kbd/keymaps/i386/qwerty/</filename>.</para>
49    <para os="h">Configure the kernel via a menu-driven interface.
50    Please note that the udev bootscript requires "rtc" and "tmpfs" to be
51    enabled and built into the kernel, not as modules. BLFS has
52    some information regarding particular kernel configuration requirements of
53    packages outside of CLFS at <ulink
54    url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para>
56<screen os="i"><userinput>make menuconfig</userinput></screen>
58    <para os="j">Alternatively, <command>make oldconfig</command> may be more
59    appropriate in some situations. See the <filename>README</filename>
60    file for more information.</para>
62    <para os="k">If desired, skip kernel configuration by copying the kernel
63    config file, <filename>.config</filename>, from the host system
64    (assuming it is available) to the root directory of the unpacked kernel
65    sources. However, we do not recommend this option. It is often better
66    to explore all the configuration menus and create the kernel configuration
67    from scratch.</para>
69    <para os="m">Compile the kernel image and modules:</para>
71<screen os="n"><userinput>make</userinput></screen>
73    <para os="o">If using kernel modules, an
74    <filename>/etc/modprobe.conf</filename> file may be needed.
75    Information pertaining to modules and kernel configuration is
76    located in the kernel documentation in the <filename
77    class="directory">Documentation</filename> directory of the kernel
78    sources tree. Also, <filename>modprobe.conf(5)</filename> may
79    be of interest.</para>
81    <para os="p">Be very careful when reading other documentation relating to
82    kernel modules because it usually applies to 2.4.x kernels only. As
83    far as we know, kernel configuration issues specific to Hotplug and
84    Udev are not documented. The problem is that Udev will create a device
85    node only if Hotplug or a user-written script inserts the corresponding
86    module into the kernel, and not all modules are detectable by Hotplug.
87    Note that statements like the one below in the
88    <filename>/etc/modprobe.conf</filename> file do not work with Udev:</para>
90<screen os="q"><literal>alias char-major-XXX some-module</literal></screen>
92    <para os="r">Because of the complications with Udev and modules,
93    we strongly recommend starting with a completely non-modular kernel
94    configuration, especially if this is the first time using Udev.</para>
96    <para os="s">Install the modules, if the kernel configuration uses
97    them:</para>
99<screen os="t"><userinput>make modules_install</userinput></screen>
101    <para os="u">After kernel compilation is complete, additional steps are
102    required to complete the installation. Some files need to be copied to
103    the <filename class="directory">/boot</filename> directory.</para>
105    <para os="v">Issue the following command to install the kernel:</para>
107<screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
109    <para os="w"><filename></filename> is a symbol file for the kernel.
110    It maps the function entry points of every function in the kernel API,
111    as well as the addresses of the kernel data structures for the running
112    kernel. Issue the following command to install the map file:</para>
114<screen os="w1"><userinput>cp /boot/;</userinput></screen>
116    <para os="x">The kernel configuration file <filename>.config</filename>
117    produced by the <command>make menuconfig</command> step above contains
118    all the configuration selections for the kernel that was just compiled.
119    It is a good idea to keep this file for future reference:</para>
121<screen os="x1"><userinput>cp .config /boot/config-&linux-version;</userinput></screen>
123    <para os="y">It is important to note that the files in the kernel source
124    directory are not owned by <systemitem class="username">root</systemitem>.
125    Whenever a package is unpacked as user <systemitem
126    class="username">root</systemitem> (like we did
127    inside chroot), the files have the user and group IDs of whatever
128    they were on the packager's computer. This is usually not a problem
129    for any other package to be installed because the source tree is
130    removed after the installation. However, the Linux source tree is
131    often retained for a long time.  Because of this, there is a chance
132    that whatever user ID the packager used will be assigned to somebody
133    on the machine. That person would then have write access to the kernel
134    source.</para>
136    <para os="y1">If the kernel source tree is going to retained, run
137    <command>chown -R 0:0</command> on the <filename
138    class="directory">linux-&linux-version;</filename> directory to
139    ensure all files are owned by user <systemitem
140    class="username">root</systemitem>.</para>
142    <warning os="z">
143      <para>Some kernel documentation recommends creating a symlink from
144      <filename class="symlink">/usr/src/linux</filename> pointing to the
145      kernel source directory. This is specific to kernels prior to the
146      2.6 series and <emphasis>must not</emphasis> be created on a CLFS
147      system as it can cause problems for packages you may wish to build
148      once your base CLFS system is complete.</para>
150      <para>Also, the headers in the system's <filename
151      class="directory">include</filename> directory should
152      <emphasis>always</emphasis> be the ones against which Glibc was
153      compiled (from the Linux-Headers package) and should
154      <emphasis>never</emphasis> be replaced by the kernel headers.</para>
155    </warning>
157  </sect2>
159  <sect2 id="contents-kernel" role="content">
160    <title>Contents of Linux</title>
162    <segmentedlist>
163      <segtitle>Installed files</segtitle>
165      <seglistitem>
166        <seg>config-[linux-version], lfskernel-[linux-version],
167        and[linux-version]</seg>
168      </seglistitem>
169    </segmentedlist>
171    <variablelist>
172      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
173      <?dbfo list-presentation="list"?>
174      <?dbhtml list-presentation="table"?>
176      <varlistentry id="config">
177        <term><filename>config-[linux-version]</filename></term>
178        <listitem>
179          <para>Contains all the configuration selections for the kernel</para>
180          <indexterm zone="ch-bootable-kernel config">
181            <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary>
182          </indexterm>
183        </listitem>
184      </varlistentry>
186      <varlistentry id="lfskernel">
187        <term><filename>lfskernel-[linux-version]</filename></term>
188        <listitem>
189          <para>The engine of the Linux system. When turning on the
190          computer, the kernel is the first part of the operating system
191          that gets loaded. It detects and initializes all components of
192          the computer's hardware, then makes these components available
193          as a tree of files to the software and turns a single CPU into
194          a multitasking machine capable of running scores of programs
195          seemingly at the same time.</para>
196          <indexterm zone="ch-bootable-kernel lfskernel">
197            <primary sortas="b-lfskernel">lfskernel-[linux-version]</primary>
198          </indexterm>
199        </listitem>
200      </varlistentry>
202      <varlistentry id="">
203        <term><filename>[linux-version]</filename></term>
204        <listitem>
205          <para>A list of addresses and symbols; it maps the entry points
206          and addresses of all the functions and data structures in the
207          kernel</para>
208          <indexterm zone="ch-bootable-kernel">
209            <primary sortas="e-/boot/">/boot/[linux-version]</primary>
210          </indexterm>
211        </listitem>
212      </varlistentry>
214    </variablelist>
216  </sect2>
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