source: bootable/x86/kernel.xml @ bf8c11f

Last change on this file since bf8c11f was bf8c11f, checked in by Jim Gifford <clfs@…>, 18 years ago

r627@server (orig r625): jim | 2005-10-31 12:59:34 -0800
Import of Cross-LFS Book

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File size: 10.4 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  <!ENTITY % patches-entities SYSTEM "../../patches.ent">
6  %general-entities;
7  %patches-entities;
10<sect1 id="ch-bootable-kernel" role="wrap">
11  <?dbhtml filename="kernel.html"?>
13  <title>Linux-&linux-x86-version;</title>
15  <indexterm zone="ch-bootable-kernel">
16    <primary sortas="a-Linux">Linux</primary>
17  </indexterm>
19  <sect2 role="package"><title/>
20    <para>The Linux package contains the Linux kernel.</para>
22    <segmentedlist>
23      <segtitle>&buildtime;</segtitle>
24      <segtitle>&diskspace;</segtitle>
26      <seglistitem>
27        <seg>Not checked yet</seg>
28        <seg>Not checked yet</seg>
29      </seglistitem>
30    </segmentedlist>
32    <segmentedlist>
33      <segtitle>&dependencies;</segtitle>
35      <seglistitem>
36        <seg>Bash, Binutils, Coreutils, Findutils, GCC, Glibc, Grep,
37        Gzip, Make, Modutils, Perl, and Sed</seg>
38      </seglistitem>
39    </segmentedlist>
41  </sect2>
43  <sect2 role="installation">
44    <title>Installation of the kernel</title>
46    <para os="a">Building the kernel involves a few steps&mdash;configuration,
47    compilation, and installation. Read the <filename>README</filename>
48    file in the kernel source tree for alternative methods to the way this
49    book configures the kernel.</para>
51    <para os="b">Prepare for compilation by running the following command:</para>
53<screen os="c"><userinput>make mrproper</userinput></screen>
55    <para os="d">This ensures that the kernel tree is absolutely clean. The
56    kernel team recommends that this command be issued prior to each
57    kernel compilation. Do not rely on the source tree being clean after
58    un-tarring.</para>
60    <para os="e">If, in <xref linkend="ch-scripts-console" role=","/> it was
61    decided to compile the keymap into the kernel, issue the command
62    below:</para>
64<screen os="f"><userinput>loadkeys -m /usr/share/kbd/keymaps/<replaceable>[path to  keymap]</replaceable> &gt; \
65    drivers/char/defkeymap.c</userinput></screen>
67    <para os="g">For example, if using a Dutch keyboard, use
68    <filename>/usr/share/kbd/keymaps/i386/qwerty/</filename>.</para>
70    <para os="h">Configure the kernel via a menu-driven interface. BLFS has
71    some information regarding particular kernel configuration requirements of
72    packages outside of LFS at <ulink
73    url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para>
75<screen os="i"><userinput>make menuconfig</userinput></screen>
77    <para os="j">Alternatively, <command>make oldconfig</command> may be more
78    appropriate in some situations. See the <filename>README</filename>
79    file for more information.</para>
81    <para os="k">If desired, skip kernel configuration by copying the kernel
82    config file, <filename>.config</filename>, from the host system
83    (assuming it is available) to the root directory of the unpacked kernel
84    sources. However, we do not recommend this option. It is often better
85    to explore all the configuration menus and create the kernel configuration
86    from scratch.</para>
88    <note os="l">
89      <para>Linux-2.6 kernel series requires to be compiled with GCC-3.x or
90      later, in this case &gcc-version;. It is not recommended to compile the
91      kernel with GCC-2.95.x, as this causes failures in the Glibc test suite.
92      Normally, this wouldn't be mentioned as LFS doesn't build GCC-2.95.x.
93      Unfortunately, the kernel documentation is outdated and still claims
94      GCC-2.95.3 is the recommended compiler.</para>
95    </note>
97    <para os="m">Compile the kernel image and modules:</para>
99<screen os="n"><userinput>make</userinput></screen>
101    <para os="o">If using kernel modules, an
102    <filename>/etc/modprobe.conf</filename> file may be needed.
103    Information pertaining to modules and kernel configuration is
104    located in the kernel documentation in the <filename
105    class="directory">Documentation</filename> directory of the kernel
106    sources tree. Also, <filename>modprobe.conf(5)</filename> may
107    be of interest.</para>
109    <para os="p">Be very careful when reading other documentation relating to
110    kernel modules because it usually applies to 2.4.x kernels only. As
111    far as we know, kernel configuration issues specific to Hotplug and
112    Udev are not documented. The problem is that Udev will create a device
113    node only if Hotplug or a user-written script inserts the corresponding
114    module into the kernel, and not all modules are detectable by Hotplug.
115    Note that statements like the one below in the
116    <filename>/etc/modprobe.conf</filename> file do not work with Udev:</para>
118<screen os="q"><literal>alias char-major-XXX some-module</literal></screen>
120    <para os="r">Because of the complications with Hotplug, Udev, and modules,
121    we strongly recommend starting with a completely non-modular kernel
122    configuration, especially if this is the first time using Udev.</para>
124    <para os="s">Install the modules, if the kernel configuration uses
125    them:</para>
127<screen os="t"><userinput>make modules_install</userinput></screen>
129    <para os="u">After kernel compilation is complete, additional steps are
130    required to complete the installation. Some files need to be copied to
131    the <filename class="directory">/boot</filename> directory.</para>
133    <para os="v">Issue the following command to install the kernel:</para>
135<screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-x86-version;</userinput></screen>
137    <para os="w"><filename></filename> is a symbol file for the kernel.
138    It maps the function entry points of every function in the kernel API,
139    as well as the addresses of the kernel data structures for the running
140    kernel. Issue the following command to install the map file:</para>
142<screen><userinput>cp /boot/;</userinput></screen>
144    <para os="x">The kernel configuration file <filename>.config</filename>
145    produced by the <command>make menuconfig</command> step above contains
146    all the configuration selections for the kernel that was just compiled.
147    It is a good idea to keep this file for future reference:</para>
149<screen><userinput>cp .config /boot/config-&linux-x86-version;</userinput></screen>
151    <para os="y">It is important to note that the files in the kernel source
152    directory are not owned by <systemitem class="username">root</systemitem>.
153    Whenever a package is unpacked as user <systemitem
154    class="username">root</systemitem> (like we did
155    inside chroot), the files have the user and group IDs of whatever
156    they were on the packager's computer. This is usually not a problem
157    for any other package to be installed because the source tree is
158    removed after the installation. However, the Linux source tree is
159    often retained for a long time.  Because of this, there is a chance
160    that whatever user ID the packager used will be assigned to somebody
161    on the machine. That person would then have write access to the kernel
162    source.</para>
164    <para>If the kernel source tree is going to retained, run
165    <command>chown -R 0:0</command> on the <filename
166    class="directory">linux-&linux-x86-version;</filename> directory to
167    ensure all files are owned by user <systemitem
168    class="username">root</systemitem>.</para>
170    <warning os="z">
171      <para>Some kernel documentation recommends creating a symlink from
172      <filename class="symlink">/usr/src/linux</filename> pointing to the
173      kernel source directory. This is specific to kernels prior to the
174      2.6 series and <emphasis>must not</emphasis> be created on an LFS
175      system as it can cause problems for packages you may wish to build
176      once your base LFS system is complete.</para>
178      <para>Also, the headers in the system's <filename
179      class="directory">include</filename> directory should
180      <emphasis>always</emphasis> be the ones against which Glibc was
181      compiled, that is, the ones from the Linux-Libc-Headers package,
182      and therefore, should <emphasis>never</emphasis> be replaced by
183      the kernel headers.</para>
184    </warning>
186  </sect2>
188  <sect2 id="contents-kernel" role="content">
189    <title>Contents of Linux</title>
191    <segmentedlist>
192      <segtitle>Installed files</segtitle>
194      <seglistitem>
195        <seg>config-[linux-version], lfskernel-[linux-version],
196        and[linux-version]</seg>
197      </seglistitem>
198    </segmentedlist>
200    <variablelist>
201      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
202      <?dbfo list-presentation="list"?>
203      <?dbhtml list-presentation="table"?>
205      <varlistentry id="config">
206        <term><filename>config-[linux-version]</filename></term>
207        <listitem>
208          <para>Contains all the configuration selections for the kernel</para>
209          <indexterm zone="ch-bootable-kernel config">
210            <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary>
211          </indexterm>
212        </listitem>
213      </varlistentry>
215      <varlistentry id="lfskernel">
216        <term><filename>lfskernel-[linux-version]</filename></term>
217        <listitem>
218          <para>The engine of the Linux system. When turning on the
219          computer, the kernel is the first part of the operating system
220          that gets loaded. It detects and initializes all components of
221          the computer's hardware, then makes these components available
222          as a tree of files to the software and turns a single CPU into
223          a multitasking machine capable of running scores of programs
224          seemingly at the same time.</para>
225          <indexterm zone="ch-bootable-kernel lfskernel">
226            <primary sortas="b-lfskernel">lfskernel-[linux-version]</primary>
227          </indexterm>
228        </listitem>
229      </varlistentry>
231      <varlistentry id="">
232        <term><filename>[linux-version]</filename></term>
233        <listitem>
234          <para>A list of addresses and symbols; it maps the entry points
235          and addresses of all the functions and data structures in the
236          kernel</para>
237          <indexterm zone="ch-bootable-kernel">
238            <primary sortas="e-/boot/">/boot/[linux-version]</primary>
239          </indexterm>
240        </listitem>
241      </varlistentry>
243    </variablelist>
245  </sect2>
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