1 | <?xml version="1.0" encoding="ISO-8859-1"?>
|
---|
2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
|
---|
3 | <!ENTITY % general-entities SYSTEM "../general.ent">
|
---|
4 | %general-entities;
|
---|
5 | ]>
|
---|
6 | <sect1 id="ch-bootable-kernel" role="wrap">
|
---|
7 | <title>Linux-&linux-version;</title>
|
---|
8 | <?dbhtml filename="kernel.html"?>
|
---|
9 |
|
---|
10 | <indexterm zone="ch-bootable-kernel"><primary sortas="a-Linux">Linux</primary></indexterm>
|
---|
11 |
|
---|
12 | <sect2 role="package"><title/>
|
---|
13 | <para>The Linux package contains the kernel and the header files.</para>
|
---|
14 |
|
---|
15 | <segmentedlist>
|
---|
16 | <segtitle>&buildtime;</segtitle>
|
---|
17 | <segtitle>&diskspace;</segtitle>
|
---|
18 | <seglistitem><seg>4.20 SBU</seg>
|
---|
19 | <seg>181 MB</seg></seglistitem>
|
---|
20 | </segmentedlist>
|
---|
21 |
|
---|
22 | <segmentedlist>
|
---|
23 | <segtitle>&dependencies;</segtitle>
|
---|
24 | <seglistitem><seg>Bash, Binutils, Coreutils, Findutils,
|
---|
25 | GCC, Glibc, Grep, Gzip, Make, Modutils, Perl, and Sed</seg></seglistitem>
|
---|
26 | </segmentedlist>
|
---|
27 | </sect2>
|
---|
28 |
|
---|
29 | <sect2 role="installation">
|
---|
30 | <title>Installation of the kernel</title>
|
---|
31 |
|
---|
32 | <para>Building the kernel involves a few steps—configuration,
|
---|
33 | compilation, and installation. Read the <filename>README</filename>
|
---|
34 | file in the kernel source tree for alternate methods to the way this
|
---|
35 | book configures the kernel.</para>
|
---|
36 |
|
---|
37 | <para>Prepare for compilation by running the following command:</para>
|
---|
38 |
|
---|
39 | <screen><userinput>make mrproper</userinput></screen>
|
---|
40 |
|
---|
41 | <para>This ensures that the kernel tree is absolutely clean. The
|
---|
42 | kernel team recommends that this command be issued prior to each
|
---|
43 | kernel compilation. Do not rely on the source tree being clean after
|
---|
44 | un-tarring.</para>
|
---|
45 |
|
---|
46 | <para>If, in <xref linkend="ch-scripts-console" role=","/> it was decided to
|
---|
47 | compile the keymap into the kernel, issue the command below:</para>
|
---|
48 |
|
---|
49 | <screen><userinput>loadkeys -m /usr/share/kbd/keymaps/<replaceable>[path to keymap]</replaceable> > \
|
---|
50 | drivers/char/defkeymap.c</userinput></screen>
|
---|
51 |
|
---|
52 | <para>For example, if using a Dutch keyboard, use
|
---|
53 | <filename>/usr/share/kbd/keymaps/i386/qwerty/nl.map.gz</filename>.</para>
|
---|
54 |
|
---|
55 | <para>Configure the kernel via a menu-driven interface BLFS has some
|
---|
56 | information regarding particular kernel configuration requirements of
|
---|
57 | packages outside of LFS at <ulink
|
---|
58 | url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para>
|
---|
59 |
|
---|
60 | <screen><userinput>make menuconfig</userinput></screen>
|
---|
61 |
|
---|
62 | <para>Alternatively, <command>make oldconfig</command> may be more appropriate in some
|
---|
63 | situations. See the <filename>README</filename> file for more
|
---|
64 | information.</para>
|
---|
65 |
|
---|
66 | <note><para>When configuring the kernel, be sure to enable the
|
---|
67 | <quote>Support for hot-pluggable devices</quote> option under the
|
---|
68 | <quote>General Setup</quote> menu. This enables hotplug events that
|
---|
69 | are used by <command>udev</command> to populate the <filename
|
---|
70 | class="directory">/dev</filename> directory with device
|
---|
71 | nodes.</para></note>
|
---|
72 |
|
---|
73 | <para>If desired, skip kernel configuration by copying the kernel
|
---|
74 | config file, <filename>.config</filename>, from the host system
|
---|
75 | (assuming it is available) to the unpacked <filename
|
---|
76 | class="directory">linux-&linux-version;</filename> directory. However,
|
---|
77 | we do not recommend this option. It is often better to explore all the
|
---|
78 | configuration menus and create the kernel configuration from
|
---|
79 | scratch.</para>
|
---|
80 |
|
---|
81 | <para>For POSIX-shared memory support, ensure that the kernel config
|
---|
82 | option <quote>Virtual memory file system support</quote> is enabled.
|
---|
83 | It resides within the <quote>File systems</quote> menu and is normally
|
---|
84 | enabled by default.</para>
|
---|
85 |
|
---|
86 | <para>LFS bootscripts make the assumption that either both
|
---|
87 | <quote>Support for Host-side USB</quote> and <quote>USB device
|
---|
88 | filesystem</quote> have been compiled directly into the kernel, or
|
---|
89 | that neither is compiled at all. Bootscripts will not work properly
|
---|
90 | if it is a module (usbcore.ko).</para>
|
---|
91 |
|
---|
92 | <note><para>NPTL requires the kernel to be compiled with GCC 3.x, in
|
---|
93 | this case &gcc-version;. Compiling with 2.95.x is known to cause failures in
|
---|
94 | the glibc test suite, so it is not recommended to compile the kernel
|
---|
95 | with gcc 2.95.x.</para></note>
|
---|
96 |
|
---|
97 | <para>Compile the kernel image and modules:</para>
|
---|
98 |
|
---|
99 | <screen><userinput>make</userinput></screen>
|
---|
100 |
|
---|
101 | <para>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">linux-&linux-version;/Documentation</filename>
|
---|
106 | directory. The <emphasis>modprobe.conf</emphasis> man page may also be
|
---|
107 | of interest.</para>
|
---|
108 |
|
---|
109 | <para>Be very careful when reading other documentation because it
|
---|
110 | usually applies to 2.4.x kernels only. As far as we know, kernel
|
---|
111 | configuration issues specific to Hotplug and Udev are not documented.
|
---|
112 | The problem is that Udev will create a device node only if Hotplug or
|
---|
113 | a user-written script inserts the corresponding module into the
|
---|
114 | kernel, and not all modules are detectable by Hotplug. Note that
|
---|
115 | statements like the one below in the
|
---|
116 | <filename>/etc/modprobe.conf</filename> file do not work with
|
---|
117 | Udev:</para>
|
---|
118 |
|
---|
119 | <para><screen>alias char-major-XXX some-module</screen></para>
|
---|
120 |
|
---|
121 | <para>Because of the complications with Hotplug, Udev, and modules, we
|
---|
122 | strongly recommend starting with a completely non-modular kernel
|
---|
123 | configuration, especially if this is the first time using Udev.</para>
|
---|
124 |
|
---|
125 | <para>Install the modules, if the kernel configuration uses them:</para>
|
---|
126 |
|
---|
127 | <screen><userinput>make modules_install</userinput></screen>
|
---|
128 |
|
---|
129 | <para>If there are many modules and very little space, consider
|
---|
130 | stripping and compressing the modules. For most users, such
|
---|
131 | compression is not worth the time, but if the system is pressed for
|
---|
132 | space, see <ulink
|
---|
133 | url="http://www.linux-mips.org/archives/linux-mips/2002-04/msg00031.html"/>.</para>
|
---|
134 |
|
---|
135 | <para>After kernel compilation is complete, additional steps are
|
---|
136 | required to complete the installation. Some files need to be copied to
|
---|
137 | the <filename class="directory">/boot</filename> directory.</para>
|
---|
138 |
|
---|
139 | <para>The path to the kernel image may vary depending on the platform
|
---|
140 | being used. Issue the following command to install the kernel:</para>
|
---|
141 |
|
---|
142 | <screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
|
---|
143 |
|
---|
144 | <para><filename>System.map</filename> is a symbol file for the kernel.
|
---|
145 | It maps the function entry points of every function in the kernel API,
|
---|
146 | as well as the addresses of the kernel data structures for the running
|
---|
147 | kernel. Issue the following command to install the map file:</para>
|
---|
148 |
|
---|
149 | <screen><userinput>cp System.map /boot/System.map-&linux-version;</userinput></screen>
|
---|
150 |
|
---|
151 | <para>The kernel configuration file <filename>.config</filename>
|
---|
152 | produced by the <command>make menuconfig</command> step
|
---|
153 | above contains all the configuration selections for the kernel
|
---|
154 | that was just compiled. It is a good idea to keep this file for future
|
---|
155 | reference:</para>
|
---|
156 |
|
---|
157 | <screen><userinput>cp .config /boot/config-&linux-version;</userinput></screen>
|
---|
158 |
|
---|
159 | <para>It is important to note that the files in the kernel source
|
---|
160 | directory are not owned by <emphasis>root</emphasis>. Whenever a
|
---|
161 | package is unpacked as user <emphasis>root</emphasis> (like we did
|
---|
162 | inside chroot), the files have the user and group IDs of whatever
|
---|
163 | they were on the packager's computer. This is usually not a problem
|
---|
164 | for any other package to be installed because the source tree is
|
---|
165 | removed after the installation. However, the Linux source tree is
|
---|
166 | often retained for a long time. Because of this, there is a chance
|
---|
167 | that whatever user ID the packager used will be assigned to somebody
|
---|
168 | on the machine. That person would then have write access to the kernel
|
---|
169 | source.</para>
|
---|
170 |
|
---|
171 | <para>If the kernel source tree is going to be retained, run
|
---|
172 | <command>chown -R 0:0</command> on the <filename
|
---|
173 | class="directory">linux-&linux-version;</filename> directory to ensure
|
---|
174 | all files are owned by user <emphasis>root</emphasis>.</para>
|
---|
175 |
|
---|
176 | <warning><para>Some kernel documentation recommends creating a symlink from
|
---|
177 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
|
---|
178 | source directory. This is specific to kernels prior to the 2.6 series and
|
---|
179 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
|
---|
180 | problems for packages you may wish to build once your base LFS system is
|
---|
181 | complete.</para></warning>
|
---|
182 |
|
---|
183 | </sect2>
|
---|
184 |
|
---|
185 |
|
---|
186 | <sect2 id="contents-kernel" role="content"><title>Contents of Linux</title>
|
---|
187 |
|
---|
188 | <segmentedlist>
|
---|
189 | <segtitle>Installed files</segtitle>
|
---|
190 | <seglistitem><seg>kernel, kernel headers,
|
---|
191 | and System.map</seg></seglistitem>
|
---|
192 | </segmentedlist>
|
---|
193 |
|
---|
194 | <variablelist><bridgehead renderas="sect3">Short Descriptions</bridgehead>
|
---|
195 | <?dbfo list-presentation="list"?>
|
---|
196 | <?dbhtml list-presentation="table"?>
|
---|
197 |
|
---|
198 | <varlistentry id="kernel">
|
---|
199 | <term><filename>kernel</filename></term>
|
---|
200 | <listitem>
|
---|
201 | <para>The engine of the Linux system. When turning on the computer,
|
---|
202 | the kernel is the first part of the operating system that gets loaded.
|
---|
203 | It detects and initializes all components of the computer's hardware,
|
---|
204 | then makes these components available as a tree of files to the
|
---|
205 | software and turns a single CPU into a multitasking machine capable
|
---|
206 | of running scores of programs seemingly at the same time.</para>
|
---|
207 | <indexterm zone="ch-bootable-kernel kernel"><primary sortas="b-kernel">kernel</primary></indexterm>
|
---|
208 | </listitem>
|
---|
209 | </varlistentry>
|
---|
210 |
|
---|
211 | <varlistentry id="kernel-headers">
|
---|
212 | <term><filename>kernel headers</filename></term>
|
---|
213 | <listitem>
|
---|
214 | <para>Defines the interface to the services that the kernel provides.
|
---|
215 | The headers in the system's <filename
|
---|
216 | class="directory">include</filename> directory should
|
---|
217 | <emphasis>always</emphasis> be the ones against which Glibc was
|
---|
218 | compiled and therefore, should <emphasis>not</emphasis> be replaced
|
---|
219 | when upgrading the kernel.</para>
|
---|
220 | <indexterm zone="ch-bootable-kernel kernel-headers"><primary sortas="e-kernel-headers">kernel headers</primary></indexterm>
|
---|
221 | </listitem>
|
---|
222 | </varlistentry>
|
---|
223 |
|
---|
224 | <varlistentry id="System.map">
|
---|
225 | <term><filename>System.map</filename></term>
|
---|
226 | <listitem>
|
---|
227 | <para>A list of addresses and symbols; it maps the entry points and
|
---|
228 | addresses of all the functions and data structures in the
|
---|
229 | kernel</para>
|
---|
230 | <indexterm zone="ch-bootable-kernel System.map"><primary sortas="e-/boot/System.map">/boot/System.map</primary></indexterm>
|
---|
231 | </listitem>
|
---|
232 | </varlistentry>
|
---|
233 | </variablelist>
|
---|
234 |
|
---|
235 | </sect2>
|
---|
236 |
|
---|
237 | </sect1>
|
---|
238 |
|
---|