source: BOOK/bootable/x86/kernel.xml @ ca8dde0

clfs-3.0.0-systemdclfs-3.0.0-sysvinitsystemdsysvinit
Last change on this file since ca8dde0 was ca8dde0, checked in by William Harrington <kb0iic@…>, 10 years ago

Add more configure options and some configure option reasons to kernel configureation notes.

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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    <note os="kc"><para>A good starting place for setting up the kernel
40    configuration is to run <command>make defconfig</command>. This will set the    base configuration to a good state that takes your current system
41    architecture into account.</para>
42
43    <para>Be sure to enable or disable following features or the system might
44    not work correctly or boot at all. Refer to
45    <filename>/usr/share/doc/systemd-&systemd-version;/README</filename>:</para>
46
47    <screen role="nodump">General setup  ---&gt;
48  [*] open by fhandle syscalls
49  [ ] Auditing support
50  [*] Control Group support
51Processor type and features  ---&gt;
52  [*] Enable seccomp to safely compute untrusted bytecode
53Networking support  ---&gt;
54  Networking options  ---&gt;
55    &lt;*&gt; The IPv6 protocol
56Device Drivers  ---&gt;
57  Generic Driver Options  ---&gt;
58    ()  path to uevent helper
59    [*] Maintain a devtmpfs filesystem to mount at /dev
60    [ ] Fallback user-helper invocation for firmware loading
61File systems  ---&gt;
62  [*] Inotify support for userspace
63  &lt;*&gt; Kernel automounter version 4 support (also supports v3)
64  Pseudo filesystems  ---&gt;
65    [*] Tmpfs POSIX Access Control Lists
66    [*] Tmpfs extended attributes
67Firmware Drivers ---&gt;
68  EFI (Extensible Firmware Interface) Support ---&gt;
69    &lt;*&gt; EFI Variable Support via sysfs
70-*- Enable the block layer ---&gt;
71  Partition Types ---&gt;
72    [*] Advanced partition selection
73    [*]   EFI GUID Partition support
74Kernel Hacking ---&gt;
75  [*] Collect scheduler debugging info
76  [*] Collect scheduler statistics</screen></note>
77
78    <note os="kd"><para>While "The IPv6 Protocol" is not strictly required, it
79    is highly recommended by the Systemd developers. "EFI Variable support" and
80    "EFI GUID Partition support" are for UEFI systems. "Collect scheduler
81    debugging info" and "Collect scheduler statistics" is for systemd-bootchart.
82    </para></note>
83
84    <para os="h">Configure the kernel via a menu-driven interface.
85    CBLFS has some information regarding particular kernel configuration
86    requirements of packages outside of CLFS at <ulink
87    url="&cblfs-root;"/>:</para>
88
89<screen os="i"><userinput>make menuconfig</userinput></screen>
90
91    <para os="j">Alternatively, <command>make oldconfig</command> may be more
92    appropriate in some situations. See the <filename>README</filename>
93    file for more information.</para>
94
95    <para os="k">If desired, skip kernel configuration by copying the kernel
96    config file, <filename>.config</filename>, from the host system
97    (assuming it is available) to the root directory of the unpacked kernel
98    sources. However, we do not recommend this option. It is often better
99    to explore all the configuration menus and create the kernel configuration
100    from scratch.</para>
101
102    <para os="m">Compile the kernel image and modules:</para>
103
104<screen os="n"><userinput>make</userinput></screen>
105
106    <para os="o">If using kernel modules, an
107    <filename>/etc/modprobe.conf</filename> file may be needed.
108    Information pertaining to modules and kernel configuration is
109    located in the kernel documentation in the <filename
110    class="directory">Documentation</filename> directory of the kernel
111    sources tree. Also, <filename>modprobe.conf(5)</filename> may
112    be of interest.</para>
113
114    <para os="p">Be very careful when reading other documentation relating to
115    kernel modules because it usually applies to 2.4.x kernels only. As
116    far as we know, kernel configuration issues specific to Hotplug and
117    Eudev are not documented. The problem is that Eudev will create a device
118    node only if Hotplug or a user-written script inserts the corresponding
119    module into the kernel, and not all modules are detectable by Hotplug.
120    Note that statements like the one below in the
121    <filename>/etc/modprobe.conf</filename> file do not work with Eudev:</para>
122
123<screen os="q"><literal>alias char-major-XXX some-module</literal></screen>
124
125    <para os="r">Because of the complications with Eudev and modules,
126    we strongly recommend starting with a completely non-modular kernel
127    configuration, especially if this is the first time using Eudev.</para>
128
129    <para os="s">Install the modules, if the kernel configuration uses
130    them:</para>
131
132<screen os="t"><userinput>make modules_install</userinput></screen>
133
134    <para os="s2">Install the firmware, if the kernel configuration uses
135    them:</para>
136
137<screen os="t2"><userinput>make firmware_install</userinput></screen>
138
139    <para os="u">After kernel compilation is complete, additional steps are
140    required to complete the installation. Some files need to be copied to
141    the <filename class="directory">/boot</filename> directory.</para>
142
143    <para os="v">Issue the following command to install the kernel:</para>
144
145<screen><userinput>cp -v arch/i386/boot/bzImage /boot/vmlinuz-clfs-&linux-version;</userinput></screen>
146
147    <para os="w"><filename>System.map</filename> is a symbol file for the kernel.
148    It maps the function entry points of every function in the kernel API,
149    as well as the addresses of the kernel data structures for the running
150    kernel. Issue the following command to install the map file:</para>
151
152<screen os="w1"><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
153
154    <para os="x">The kernel configuration file <filename>.config</filename>
155    produced by the <command>make menuconfig</command> step above contains
156    all the configuration selections for the kernel that was just compiled.
157    It is a good idea to keep this file for future reference:</para>
158
159<screen os="x1"><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
160
161    <para os="y">It is important to note that the files in the kernel source
162    directory are not owned by <systemitem class="username">root</systemitem>.
163    Whenever a package is unpacked as user <systemitem
164    class="username">root</systemitem> (like we do inside the final-system
165    build environment), the files have the user and group IDs of whatever
166    they were on the packager's computer. This is usually not a problem
167    for any other package to be installed because the source tree is
168    removed after the installation. However, the Linux source tree is
169    often retained for a long time. Because of this, there is a chance
170    that whatever user ID the packager used will be assigned to somebody
171    on the machine. That person would then have write access to the kernel
172    source.</para>
173
174    <para os="y1">If the kernel source tree is going to retained, run
175    <command>chown -R 0:0</command> on the <filename
176    class="directory">linux-&linux-version;</filename> directory to
177    ensure all files are owned by user <systemitem
178    class="username">root</systemitem>.</para>
179
180    <warning os="z">
181      <para>Some kernel documentation recommends creating a symlink from
182      <filename class="symlink">/usr/src/linux</filename> pointing to the
183      kernel source directory. This is specific to kernels prior to the
184      2.6 series and <emphasis>must not</emphasis> be created on a CLFS
185      system as it can cause problems for packages you may wish to build
186      once your base CLFS system is complete.</para>
187
188      <para>Also, the headers in the system's <filename
189      class="directory">include</filename> directory should
190      <emphasis>always</emphasis> be the ones against which Glibc was
191      compiled and should <emphasis>never</emphasis> be replaced by headers
192      from a different kernel version.</para>
193    </warning>
194
195  </sect2>
196
197  <sect2 id="contents-kernel" role="content">
198    <title>Contents of Linux</title>
199
200    <segmentedlist>
201      <segtitle>Installed files</segtitle>
202      <segtitle>Installed directory</segtitle>
203
204      <seglistitem>
205        <seg>config-[linux-version], clfskernel-[linux-version],
206        and System.map-[linux-version]</seg>
207        <seg>/lib/modules</seg>
208      </seglistitem>
209    </segmentedlist>
210
211    <variablelist>
212      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
213      <?dbfo list-presentation="list"?>
214      <?dbhtml list-presentation="table"?>
215
216      <varlistentry id="config">
217        <term><filename>config-[linux-version]</filename></term>
218        <listitem>
219          <para>Contains all the configuration selections for the kernel</para>
220          <indexterm zone="ch-bootable-kernel config">
221            <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary>
222          </indexterm>
223        </listitem>
224      </varlistentry>
225
226      <varlistentry id="clfskernel">
227        <term><filename>clfskernel-[linux-version]</filename></term>
228        <listitem>
229          <para>The engine of the Linux system. When turning on the
230          computer, the kernel is the first part of the operating system
231          that gets loaded. It detects and initializes all components of
232          the computer's hardware, then makes these components available
233          as a tree of files to the software and turns a single CPU into
234          a multitasking machine capable of running scores of programs
235          seemingly at the same time.</para>
236          <indexterm zone="ch-bootable-kernel clfskernel">
237            <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary>
238          </indexterm>
239        </listitem>
240      </varlistentry>
241
242      <varlistentry id="System.map">
243        <term><filename>System.map-[linux-version]</filename></term>
244        <listitem>
245          <para>A list of addresses and symbols; it maps the entry points
246          and addresses of all the functions and data structures in the
247          kernel</para>
248          <indexterm zone="ch-bootable-kernel System.map">
249            <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary>
250          </indexterm>
251        </listitem>
252      </varlistentry>
253
254    </variablelist>
255
256  </sect2>
257
258</sect1>
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