source: chapter10/kernel.xml@ 3d7b4f6

11.1 11.1-rc1 11.2 11.2-rc1 11.3 11.3-rc1 12.0 12.0-rc1 12.1 12.1-rc1 12.2 12.2-rc1 arm bdubbs/gcc13 multilib renodr/libudev-from-systemd s6-init trunk xry111/arm64 xry111/arm64-12.0 xry111/clfs-ng xry111/lfs-next xry111/loongarch xry111/loongarch-12.0 xry111/loongarch-12.1 xry111/loongarch-12.2 xry111/mips64el xry111/multilib xry111/pip3 xry111/rust-wip-20221008 xry111/update-glibc
Last change on this file since 3d7b4f6 was 3d7b4f6, checked in by Xi Ruoyao <xry111@…>, 3 years ago

clean up after condxml merge

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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 <sect1info condition="script">
12 <productname>kernel</productname>
13 <productnumber>&linux-version;</productnumber>
14 <address>&linux-url;</address>
15 </sect1info>
16
17 <title>Linux-&linux-version;</title>
18
19 <indexterm zone="ch-bootable-kernel">
20 <primary sortas="a-Linux">Linux</primary>
21 </indexterm>
22
23 <sect2 role="package">
24 <title/>
25
26 <para>The Linux package contains the Linux kernel.</para>
27
28 <segmentedlist>
29 <segtitle>&buildtime;</segtitle>
30 <segtitle>&diskspace;</segtitle>
31
32 <seglistitem>
33 <seg>&linux-knl-sbu;</seg>
34 <seg>&linux-knl-du;</seg>
35 </seglistitem>
36 </segmentedlist>
37
38 </sect2>
39
40 <sect2 role="installation">
41 <title>Installation of the kernel</title>
42
43 <para>Building the kernel involves a few steps&mdash;configuration,
44 compilation, and installation. Read the <filename>README</filename> file
45 in the kernel source tree for alternative methods to the way this book
46 configures the kernel.</para>
47
48 <para>Prepare for compilation by running the following command:</para>
49
50<screen><userinput remap="pre">make mrproper</userinput></screen>
51
52 <para>This ensures that the kernel tree is absolutely clean. The
53 kernel team recommends that this command be issued prior to each
54 kernel compilation. Do not rely on the source tree being clean after
55 un-tarring.</para>
56
57 <para>There are several ways to configure the kernel options. Usually,
58 This is done through a menu-driven interface, for example:</para>
59
60<screen role="nodump"><userinput>make menuconfig</userinput></screen>
61
62 <variablelist>
63 <title>The meaning of optional make environment variables:</title>
64
65 <varlistentry>
66 <term><parameter>LANG=&lt;host_LANG_value&gt; LC_ALL=</parameter></term>
67 <listitem>
68 <para>This establishes the locale setting to the one used on the
69 host. This may be needed for a proper menuconfig ncurses interface
70 line drawing on a UTF-8 linux text console.</para>
71
72 <para>If used, be sure to replace
73 <replaceable>&lt;host_LANG_value&gt;</replaceable> by the value of
74 the <envar>$LANG</envar> variable from your host. You can
75 alternatively use instead the host's value of <envar>$LC_ALL</envar>
76 or <envar>$LC_CTYPE</envar>.</para>
77 </listitem>
78 </varlistentry>
79
80 <varlistentry>
81 <term><command>make menuconfig</command></term>
82 <listitem>
83 <para>This launches an ncurses menu-driven interface. For other
84 (graphical) interfaces, type <command>make help</command>.</para>
85 </listitem>
86 </varlistentry>
87 </variablelist>
88
89 <!-- Support for compiling a keymap into the kernel is deliberately removed -->
90
91 <para>For general information on kernel configuration see <ulink
92 url="&hints-root;kernel-configuration.txt"/>. BLFS has some information
93 regarding particular kernel configuration requirements of packages outside
94 of LFS at <ulink
95 url="&blfs-book;longindex.html#kernel-config-index"/>. Additional
96 information about configuring and building the kernel can be found at
97 <ulink url="http://www.kroah.com/lkn/"/> </para>
98
99 <note>
100 <para>A good starting place for setting up the kernel configuration is to
101 run <command>make defconfig</command>. This will set the base
102 configuration to a good state that takes your current system architecture
103 into account.</para>
104
105 <para>Be sure to enable/disable/set the following features or the system might
106 not work correctly or boot at all:</para>
107
108 <screen role="nodump" revision="sysv">Device Drivers ---&gt;
109 Generic Driver Options ---&gt;
110 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
111 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]</screen>
112
113 <screen role="nodump" revision="systemd">General setup -->
114 [ ] Auditing Support [CONFIG_AUDIT]
115 [*] Control Group support [CONFIG_CGROUPS]
116 [ ] Enable deprecated sysfs features to support old userspace tools [CONFIG_SYSFS_DEPRECATED]
117 [*] Configure standard kernel features (expert users) [CONFIG_EXPERT] ---&gt;
118 [*] open by fhandle syscalls [CONFIG_FHANDLE]
119Firmware Drivers ---&gt;
120 [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID]
121General architecture-dependent options ---&gt;
122 [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP]
123Networking support ---&gt;
124 Networking options ---&gt;
125 &lt;*&gt; The IPv6 protocol [CONFIG_IPV6]
126Device Drivers ---&gt;
127 Generic Driver Options ---&gt;
128 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
129 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
130 Firmware Loader ---&gt;
131 [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER]
132File systems ---&gt;
133 [*] Inotify support for userspace [CONFIG_INOTIFY_USER]
134 Pseudo filesystems ---&gt;
135 [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL]</screen>
136 </note>
137
138 <note revision="systemd">
139 <para>While "The IPv6 Protocol" is not strictly
140 required, it is highly recommended by the systemd developers.</para>
141 </note>
142
143 <para revision="sysv">There are several other options that may be desired
144 depending on the requirements for the system. For a list of options needed
145 for BLFS packages, see the <ulink
146 url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS
147 Index of Kernel Settings</ulink>
148 (&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index).</para>
149
150 <note>
151 <para>If your host hardware is using UEFI and you wish to boot the
152 LFS system with it, you should adjust some kernel configuration
153 following <ulink url="&blfs-book;postlfs/grub-setup.html#uefi-kernel">
154 the BLFS page</ulink>.</para>
155 </note>
156
157 <variablelist>
158 <title>The rationale for the above configuration items:</title>
159
160 <varlistentry>
161 <term><parameter>Support for uevent helper</parameter></term>
162 <listitem>
163 <para>Having this option set may interfere with device
164 management when using Udev/Eudev. </para>
165 </listitem>
166 </varlistentry>
167
168 <varlistentry>
169 <term><parameter>Maintain a devtmpfs</parameter></term>
170 <listitem>
171 <para>This will create automated device nodes which are populated by the
172 kernel, even without Udev running. Udev then runs on top of this,
173 managing permissions and adding symlinks. This configuration
174 item is required for all users of Udev/Eudev.</para>
175 </listitem>
176 </varlistentry>
177
178 </variablelist>
179
180 <para>Alternatively, <command>make oldconfig</command> may be more
181 appropriate in some situations. See the <filename>README</filename>
182 file for more information.</para>
183
184 <para>If desired, skip kernel configuration by copying the kernel
185 config file, <filename>.config</filename>, from the host system
186 (assuming it is available) to the unpacked <filename
187 class="directory">linux-&linux-version;</filename> directory. However,
188 we do not recommend this option. It is often better to explore all the
189 configuration menus and create the kernel configuration from
190 scratch.</para>
191
192 <para>Compile the kernel image and modules:</para>
193
194<screen><userinput remap="make">make</userinput></screen>
195
196 <para>If using kernel modules, module configuration in <filename
197 class="directory">/etc/modprobe.d</filename> may be required.
198 Information pertaining to modules and kernel configuration is
199 located in <xref linkend="ch-config-udev"/> and in the kernel
200 documentation in the <filename
201 class="directory">linux-&linux-version;/Documentation</filename> directory.
202 Also, <filename>modprobe.d(5)</filename> may be of interest.</para>
203
204 <para>Unless module support has been disabled in the kernel configuration,
205 install the modules with:</para>
206
207<screen><userinput remap="install">make modules_install</userinput></screen>
208
209 <para>After kernel compilation is complete, additional steps are
210 required to complete the installation. Some files need to be copied to
211 the <filename class="directory">/boot</filename> directory.</para>
212
213 <caution>
214 <para>If the host system has a separate /boot partition, the files copied
215 below should go there. The easiest way to do that is to bind /boot on the
216 host (outside chroot) to /mnt/lfs/boot before proceeding. As the root
217 user in the <emphasis>host system</emphasis>:</para>
218
219<screen role="nodump"><userinput>mount --bind /boot /mnt/lfs/boot</userinput></screen>
220 </caution>
221
222 <para>The path to the kernel image may vary depending on the platform being
223 used. The filename below can be changed to suit your taste, but the stem of
224 the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
225 the automatic setup of the boot process described in the next section. The
226 following command assumes an x86 architecture:</para>
227
228<screen><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
229
230 <para><filename>System.map</filename> is a symbol file for the kernel.
231 It maps the function entry points of every function in the kernel API,
232 as well as the addresses of the kernel data structures for the running
233 kernel. It is used as a resource when investigating kernel problems.
234 Issue the following command to install the map file:</para>
235
236<screen><userinput remap="install">cp -iv System.map /boot/System.map-&linux-version;</userinput></screen>
237
238 <para>The kernel configuration file <filename>.config</filename>
239 produced by the <command>make menuconfig</command> step
240 above contains all the configuration selections for the kernel
241 that was just compiled. It is a good idea to keep this file for future
242 reference:</para>
243
244<screen><userinput remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen>
245
246 <para>Install the documentation for the Linux kernel:</para>
247
248<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
249cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
250
251 <para>It is important to note that the files in the kernel source
252 directory are not owned by <emphasis>root</emphasis>. Whenever a
253 package is unpacked as user <emphasis>root</emphasis> (like we did
254 inside chroot), the files have the user and group IDs of whatever
255 they were on the packager's computer. This is usually not a problem
256 for any other package to be installed because the source tree is
257 removed after the installation. However, the Linux source tree is
258 often retained for a long time. Because of this, there is a chance
259 that whatever user ID the packager used will be assigned to somebody
260 on the machine. That person would then have write access to the kernel
261 source.</para>
262
263 <note>
264 <para>In many cases, the configuration of the kernel will need to be
265 updated for packages that will be installed later in BLFS. Unlike
266 other packages, it is not necessary to remove the kernel source tree
267 after the newly built kernel is installed.</para>
268
269 <para>If the kernel source tree is going to be retained, run
270 <command>chown -R 0:0</command> on the <filename
271 class="directory">linux-&linux-version;</filename> directory to ensure
272 all files are owned by user <emphasis>root</emphasis>.</para>
273 </note>
274
275 <warning>
276 <para>Some kernel documentation recommends creating a symlink from
277 <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
278 source directory. This is specific to kernels prior to the 2.6 series and
279 <emphasis>must not</emphasis> be created on an LFS system as it can cause
280 problems for packages you may wish to build once your base LFS system is
281 complete.</para>
282 </warning>
283
284 <warning>
285 <para>The headers in the system's <filename
286 class="directory">include</filename> directory (<filename
287 class="directory">/usr/include</filename>) should
288 <emphasis>always</emphasis> be the ones against which Glibc was compiled,
289 that is, the sanitised headers installed in <xref
290 linkend="ch-tools-linux-headers"/>. Therefore, they should
291 <emphasis>never</emphasis> be replaced by either the raw kernel headers
292 or any other kernel sanitized headers.</para>
293 </warning>
294
295 </sect2>
296
297 <sect2 id="conf-modprobe" role="configuration">
298 <title>Configuring Linux Module Load Order</title>
299
300 <indexterm zone="conf-modprobe">
301 <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
302 </indexterm>
303
304 <para>Most of the time Linux modules are loaded automatically, but
305 sometimes it needs some specific direction. The program that loads
306 modules, <command>modprobe</command> or <command>insmod</command>, uses
307 <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
308 needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
309 uhci_hcd) have been built as modules, they will be loaded in the correct
310 order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
311 to avoid a warning being output at boot time.</para>
312
313 <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
314 the following:</para>
315
316<screen><userinput>install -v -m755 -d /etc/modprobe.d
317cat &gt; /etc/modprobe.d/usb.conf &lt;&lt; "EOF"
318<literal># Begin /etc/modprobe.d/usb.conf
319
320install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
321install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
322
323# End /etc/modprobe.d/usb.conf</literal>
324EOF</userinput></screen>
325
326 </sect2>
327
328 <sect2 id="contents-kernel" role="content">
329 <title>Contents of Linux</title>
330
331 <segmentedlist>
332 <segtitle>Installed files</segtitle>
333 <segtitle>Installed directories</segtitle>
334
335 <seglistitem>
336 <seg>config-&linux-version;,
337 vmlinuz-&linux-version;-lfs-&version;,
338 and System.map-&linux-version;</seg>
339 <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
340 </seglistitem>
341 </segmentedlist>
342
343 <variablelist>
344 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
345 <?dbfo list-presentation="list"?>
346 <?dbhtml list-presentation="table"?>
347
348 <varlistentry id="config">
349 <term><filename>config-&linux-version;</filename></term>
350 <listitem>
351 <para>Contains all the configuration selections for the kernel</para>
352 <indexterm zone="ch-bootable-kernel config">
353 <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
354 </indexterm>
355 </listitem>
356 </varlistentry>
357
358 <varlistentry id="lfskernel">
359 <term><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term>
360 <listitem>
361 <para>The engine of the Linux system. When turning on the computer,
362 the kernel is the first part of the operating system that gets loaded.
363 It detects and initializes all components of the computer's hardware,
364 then makes these components available as a tree of files to the
365 software and turns a single CPU into a multitasking machine capable
366 of running scores of programs seemingly at the same time</para>
367 <indexterm zone="ch-bootable-kernel lfskernel">
368 <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
369 </indexterm>
370 </listitem>
371 </varlistentry>
372
373 <varlistentry id="System.map">
374 <term><filename>System.map-&linux-version;</filename></term>
375 <listitem>
376 <para>A list of addresses and symbols; it maps the entry points and
377 addresses of all the functions and data structures in the
378 kernel</para>
379 <indexterm zone="ch-bootable-kernel System.map">
380 <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
381 </indexterm>
382 </listitem>
383 </varlistentry>
384
385 </variablelist>
386
387 </sect2>
388
389</sect1>
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