1 | <?xml version="1.0" encoding="ISO-8859-1"?>
|
---|
2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
|
---|
3 | <!ENTITY % general-entities SYSTEM "../general.ent">
|
---|
4 | %general-entities;
|
---|
5 | ]>
|
---|
6 | <sect1 id="ch-bootable-kernel" xreflabel="Linux" 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>All default options: 4.20 SBU</seg>
|
---|
19 | <seg>All default options: 181 MB</seg></seglistitem>
|
---|
20 | </segmentedlist>
|
---|
21 |
|
---|
22 | <segmentedlist>
|
---|
23 | <segtitle>Linux installation depends on</segtitle>
|
---|
24 | <seglistitem><seg>Bash, Binutils, Coreutils, Findutils,
|
---|
25 | GCC, Glibc, Grep, Gzip, Make, Modutils, Perl, 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, compilation, and
|
---|
33 | installation. If you don't like the way this book configures the kernel, view
|
---|
34 | the <filename>README</filename> file in the kernel source tree for alternative
|
---|
35 | methods.</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 kernel team
|
---|
42 | recommends that this command be issued prior to <emphasis>each</emphasis>
|
---|
43 | kernel compilation. You shouldn't rely on the source tree being clean after
|
---|
44 | un-tarring.</para>
|
---|
45 |
|
---|
46 | <para>Also, ensure that the kernel does not attempt to pass hotplugging events
|
---|
47 | to userspace until userspace specifies that it is ready:</para>
|
---|
48 |
|
---|
49 | <screen><userinput>sed -i 's@/sbin/hotplug@/bin/true@' kernel/kmod.c</userinput></screen>
|
---|
50 |
|
---|
51 | <para>If, in <xref linkend="ch-scripts-console"/>, you decided you want
|
---|
52 | to compile the keymap into the kernel, issue the command below:</para>
|
---|
53 |
|
---|
54 | <screen><userinput>loadkeys -m /usr/share/kbd/keymaps/<replaceable>[path to keymap]</replaceable> > \
|
---|
55 | <replaceable>[unpacked sources dir]</replaceable>/linux-&linux-version;/drivers/char/defkeymap.c</userinput></screen>
|
---|
56 |
|
---|
57 | <para>For example, if you have a Dutch keyboard, you would use
|
---|
58 | <filename>/usr/share/kbd/keymaps/i386/qwerty/nl.map.gz</filename>.</para>
|
---|
59 |
|
---|
60 | <para>Configure the kernel via a menu-driven interface:</para>
|
---|
61 |
|
---|
62 | <screen><userinput>make menuconfig</userinput></screen>
|
---|
63 |
|
---|
64 | <para><command>make oldconfig</command> may be more appropriate in some
|
---|
65 | situations. See the <filename>README</filename> file for more
|
---|
66 | information.</para>
|
---|
67 |
|
---|
68 | <para>If you wish, you may skip kernel configuration by simply copying the
|
---|
69 | kernel config file, <filename>.config</filename>, from your host system
|
---|
70 | (assuming it is available) to the unpacked <filename class="directory">linux-&linux-version;</filename>
|
---|
71 | directory. However, we
|
---|
72 | don't recommend this option. You're much better off exploring all the
|
---|
73 | configuration menus and creating your own kernel configuration from
|
---|
74 | scratch.</para>
|
---|
75 |
|
---|
76 | <para>For POSIX shared memory support, ensure that the kernel config option
|
---|
77 | <quote>Virtual memory file system support</quote> is enabled. It resides within
|
---|
78 | the <quote>File systems</quote> menu and is normally enabled by default.</para>
|
---|
79 |
|
---|
80 | <para>LFS bootscripts make the assumption that you either compile
|
---|
81 | both <quote>Support for Host-side USB</quote> and
|
---|
82 | <quote>USB device filesystem</quote> directly into the kernel, or don't compile them at
|
---|
83 | all. Bootscripts will not work properly if it is a module (<filename>usbcore.ko</filename>).</para>
|
---|
84 |
|
---|
85 | <note><para>NPTL requires the kernel to be compiled with GCC 3.x, in this case
|
---|
86 | &gcc-version;. Compiling with 2.95.x is known to cause failures in the glibc
|
---|
87 | testsuite, so do <emphasis>not</emphasis> compile the kernel with gcc 2.95.x
|
---|
88 | unless you know what you're getting yourself into.</para></note>
|
---|
89 |
|
---|
90 | <para>Compile the kernel image and modules:</para>
|
---|
91 |
|
---|
92 | <screen><userinput>make</userinput></screen>
|
---|
93 |
|
---|
94 | <para>If you intend to use kernel modules, you may need an
|
---|
95 | <filename>/etc/modprobe.conf</filename> file. Information pertaining
|
---|
96 | to modules and to kernel configuration in general may be found in the
|
---|
97 | kernel documentation, which is found in the
|
---|
98 | <filename class="directory">linux-&linux-version;/Documentation</filename> directory.
|
---|
99 | The modprobe.conf man page
|
---|
100 | <!-- removed for review from tldp.org
|
---|
101 | and the kernel HOWTO at
|
---|
102 | <ulink url="http://www.tldp.org/HOWTO/Kernel-HOWTO.html"/> -->
|
---|
103 | may also be of interest to you.</para>
|
---|
104 |
|
---|
105 | <para>Be very suspicious while reading other documentation, because it
|
---|
106 | usually applies to 2.4.x kernels only. As far as the editors know, kernel
|
---|
107 | configuration issues specific to Hotplug and Udev
|
---|
108 | are documented nowhere. The problem is that Udev will create a device node
|
---|
109 | only if Hotplug or a user-written script inserts the corresponding module
|
---|
110 | into the kernel, and not all modules are detectable by Hotplug. Note
|
---|
111 | that statements like
|
---|
112 | <screen>alias char-major-XXX some-module</screen>
|
---|
113 | in <filename>/etc/modprobe.conf</filename> file don't work with
|
---|
114 | Udev, and other aliases are often unnecessary with Hotplug.</para>
|
---|
115 |
|
---|
116 | <para>Because of all those compilcations with Hotplug, Udev and modules, we
|
---|
117 | strongly recommend you to start with a completely non-modular kernel
|
---|
118 | configuration, especially if this is the first time you use Udev.</para>
|
---|
119 |
|
---|
120 | <para>Install the modules, if your kernel configuration uses them:</para>
|
---|
121 |
|
---|
122 | <screen><userinput>make modules_install</userinput></screen>
|
---|
123 |
|
---|
124 | <para>If you have a lot of modules and very little space, you may want to
|
---|
125 | consider stripping and compressing the modules. For most people such compression
|
---|
126 | isn't worth the trouble, but if you're really pressed for space, then have a look at
|
---|
127 | <ulink url="http://www.linux-mips.org/archives/linux-mips/2002-04/msg00031.html"/>.</para>
|
---|
128 |
|
---|
129 | <para>Kernel compilation has finished but more steps are required to complete
|
---|
130 | the installation. Some files need to be copied to the <filename class="directory">/boot</filename>
|
---|
131 | directory.</para>
|
---|
132 |
|
---|
133 | <para>The path to the kernel image may vary depending on the platform you're
|
---|
134 | using. Issue the following command to install the kernel:</para>
|
---|
135 |
|
---|
136 | <screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
|
---|
137 |
|
---|
138 | <para><filename>System.map</filename> is a symbol file for the kernel. It maps
|
---|
139 | the function entry points of every function in the kernel API (Application Programming Interface), as well as the
|
---|
140 | addresses of the kernel data structures for the running kernel. Issue the
|
---|
141 | following command to install the map file:</para>
|
---|
142 |
|
---|
143 | <screen><userinput>cp System.map /boot/System.map-&linux-version;</userinput></screen>
|
---|
144 |
|
---|
145 | <para><filename>.config</filename> is the kernel configuration file that was
|
---|
146 | produced by the <command>make menuconfig</command> step above. It contains all
|
---|
147 | the config selections for the kernel that was just compiled. It's a good idea
|
---|
148 | to keep this file for future reference:</para>
|
---|
149 |
|
---|
150 | <screen><userinput>cp .config /boot/config-&linux-version;</userinput></screen>
|
---|
151 |
|
---|
152 | <para>It is important to note that the files in the kernel source directory are
|
---|
153 | not owned by <emphasis>root</emphasis>. Whenever you unpack a package as user
|
---|
154 | <emphasis>root</emphasis> (like we did here inside chroot), the files end up
|
---|
155 | having the user and group IDs of whatever they were on the packager's computer.
|
---|
156 | This is usually not a problem for any other package you install because you
|
---|
157 | remove the source tree after the installation. But the Linux source tree is
|
---|
158 | often kept around for a long time, so there's a chance that whatever user ID
|
---|
159 | the packager used will be assigned to somebody on your machine and then that
|
---|
160 | person would have write access to the kernel source.</para>
|
---|
161 |
|
---|
162 | <para>If you are going to keep the kernel source tree around, you may want to
|
---|
163 | run <command>chown -R 0:0</command> on the
|
---|
164 | <filename class="directory">linux-&linux-version;</filename> directory to ensure all files are
|
---|
165 | owned by user <emphasis>root</emphasis>.</para>
|
---|
166 |
|
---|
167 | </sect2>
|
---|
168 |
|
---|
169 |
|
---|
170 | <sect2 id="contents-kernel" role="content"><title>Contents of Linux</title>
|
---|
171 |
|
---|
172 | <segmentedlist>
|
---|
173 | <segtitle>Installed files</segtitle>
|
---|
174 | <seglistitem><seg>the kernel, the kernel headers,
|
---|
175 | and the System.map</seg></seglistitem>
|
---|
176 | </segmentedlist>
|
---|
177 |
|
---|
178 | <variablelist><title>Short descriptions</title>
|
---|
179 |
|
---|
180 | <varlistentry id="kernel">
|
---|
181 | <term>The <emphasis>kernel</emphasis></term>
|
---|
182 | <listitem>
|
---|
183 | <indexterm zone="ch-bootable-kernel kernel"><primary sortas="b-kernel">kernel</primary></indexterm>
|
---|
184 | <para>is the engine of your Linux system.
|
---|
185 | When switching on your box, the kernel is the first part of your operating
|
---|
186 | system that gets loaded. It detects and initializes all the components of your
|
---|
187 | computer's hardware, then makes these components available as a tree of files
|
---|
188 | to the software, and turns a single CPU into a multi-tasking machine capable
|
---|
189 | of running scores of programs seemingly at the same time.</para>
|
---|
190 | </listitem>
|
---|
191 | </varlistentry>
|
---|
192 |
|
---|
193 | <varlistentry id="kernel-headers">
|
---|
194 | <term>The <emphasis>kernel headers</emphasis></term>
|
---|
195 | <listitem>
|
---|
196 | <indexterm zone="ch-bootable-kernel kernel-headers"><primary sortas="e-kernel-headers">kernel headers</primary></indexterm>
|
---|
197 | <para>define the interface to the
|
---|
198 | services that the kernel provides. The headers in your system's
|
---|
199 | <filename class="directory">include</filename> directory should <emphasis>always</emphasis> be
|
---|
200 | the ones against which Glibc was compiled and should therefore
|
---|
201 | <emphasis>not</emphasis> be replaced when upgrading the kernel.</para>
|
---|
202 | </listitem>
|
---|
203 | </varlistentry>
|
---|
204 |
|
---|
205 | <varlistentry id="System.map">
|
---|
206 | <term><filename>System.map</filename></term>
|
---|
207 | <listitem>
|
---|
208 | <indexterm zone="ch-bootable-kernel System.map"><primary sortas="e-/boot/System.map">/boot/System.map</primary></indexterm>
|
---|
209 | <para>is a list of addresses and symbols. It maps the entry points and addresses
|
---|
210 | of all the functions and data structures in the kernel.</para>
|
---|
211 | </listitem>
|
---|
212 | </varlistentry>
|
---|
213 | </variablelist>
|
---|
214 |
|
---|
215 | </sect2>
|
---|
216 |
|
---|
217 | </sect1>
|
---|