source: chapter10/kernel.xml@ 1c16a05

11.0 11.0-rc1 11.0-rc2 11.0-rc3 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 arm bdubbs/gcc13 ml-11.0 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/mips64el xry111/pip3 xry111/rust-wip-20221008 xry111/update-glibc
Last change on this file since 1c16a05 was 1c16a05, checked in by Xi Ruoyao <xry111@…>, 3 years ago

modify the reference to lfs-uefi hint to BLFS instead

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File size: 16.7 KB
1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "" [
4 <!ENTITY % general-entities SYSTEM "../general.ent">
5 %general-entities;
8<sect1 id="ch-bootable-kernel" role="wrap">
9 <?dbhtml filename="kernel.html"?>
11 <sect1info condition="script">
12 <productname>kernel</productname>
13 <productnumber>&linux-version;</productnumber>
14 <address>&linux-url;</address>
15 </sect1info>
17 <title>Linux-&linux-version;</title>
19 <indexterm zone="ch-bootable-kernel">
20 <primary sortas="a-Linux">Linux</primary>
21 </indexterm>
23 <sect2 role="package">
24 <title/>
26 <para>The Linux package contains the Linux kernel.</para>
28 <segmentedlist>
29 <segtitle>&buildtime;</segtitle>
30 <segtitle>&diskspace;</segtitle>
32 <seglistitem>
33 <seg>&linux-knl-sbu;</seg>
34 <seg>&linux-knl-du;</seg>
35 </seglistitem>
36 </segmentedlist>
38 </sect2>
40 <sect2 role="installation">
41 <title>Installation of the kernel</title>
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>
48 <para>Prepare for compilation by running the following command:</para>
50<screen><userinput remap="pre">make mrproper</userinput></screen>
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>
57 <para>There are several ways to configure the kernel options. Usually,
58 This is done through a menu-driven interface, for example:</para>
60<screen role="nodump"><userinput>make menuconfig</userinput></screen>
62 <variablelist>
63 <title>The meaning of optional make environment variables:</title>
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>
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>
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>
89 <!-- Support for compiling a keymap into the kernel is deliberately removed -->
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=""/> </para>
99 <note>
101 <para>A good starting place for setting up the kernel configuration is to
102 run <command>make defconfig</command>. This will set the base
103 configuration to a good state that takes your current system architecture
104 into account.</para>
106 <para>Be sure to enable/disable/set the following features or the system might
107 not work correctly or boot at all:</para>
109 <screen role="nodump" revision="sysv">Device Drivers ---&gt;
110 Generic Driver Options ---&gt;
111 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
112 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]</screen>
114 <screen role="nodump" revision="systemd">General setup -->
115 [ ] Auditing Support [CONFIG_AUDIT]
116 [*] Control Group support [CONFIG_CGROUPS]
117 [ ] Enable deprecated sysfs features to support old userspace tools [CONFIG_SYSFS_DEPRECATED]
118 [*] Configure standard kernel features (expert users) [CONFIG_EXPERT] ---&gt;
119 [*] open by fhandle syscalls [CONFIG_FHANDLE]
120Processor type and features ---&gt;
121 [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP]
122Firmware Drivers ---&gt;
123 [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID]
124Networking support ---&gt;
125 Networking options ---&gt;
126 &lt;*&gt; The IPv6 protocol [CONFIG_IPV6]
127Device Drivers ---&gt;
128 Generic Driver Options ---&gt;
129 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
130 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
131 Firmware Loader ---&gt;
132 [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER]
133File systems ---&gt;
134 [*] Inotify support for userspace [CONFIG_INOTIFY_USER]
135 Pseudo filesystems ---&gt;
136 [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL]</screen>
137 </note>
139 <note revision="systemd">
140 <para>While "The IPv6 Protocol" is not strictly
141 required, it is highly recommended by the systemd developers.</para>
142 </note>
144 <para revision="sysv">There are several other options that may be desired
145 depending on the requirements for the system. For a list of options needed
146 for BLFS packages, see the <ulink
147 url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS
148 Index of Kernel Settings</ulink>
149 (&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index).</para>
151 <note>
152 <para>If your host hardware is using UEFI and you wish to boot the
153 LFS system with it, you should adjust some kernel configuration
154 following <ulink url="&blfs-book;postlfs/grub-setup.html#uefi-kernel">
155 the BLFS page</ulink>.</para>
156 </note>
158 <variablelist>
159 <title>The rationale for the above configuration items:</title>
161 <varlistentry>
162 <term><parameter>Support for uevent helper</parameter></term>
163 <listitem>
164 <para>Having this option set may interfere with device
165 management when using Udev/Eudev. </para>
166 </listitem>
167 </varlistentry>
169 <varlistentry>
170 <term><parameter>Maintain a devtmpfs</parameter></term>
171 <listitem>
172 <para>This will create automated device nodes which are populated by the
173 kernel, even without Udev running. Udev then runs on top of this,
174 managing permissions and adding symlinks. This configuration
175 item is required for all users of Udev/Eudev.</para>
176 </listitem>
177 </varlistentry>
179 </variablelist>
181 <para>Alternatively, <command>make oldconfig</command> may be more
182 appropriate in some situations. See the <filename>README</filename>
183 file for more information.</para>
185 <para>If desired, skip kernel configuration by copying the kernel
186 config file, <filename>.config</filename>, from the host system
187 (assuming it is available) to the unpacked <filename
188 class="directory">linux-&linux-version;</filename> directory. However,
189 we do not recommend this option. It is often better to explore all the
190 configuration menus and create the kernel configuration from
191 scratch.</para>
193 <para>Compile the kernel image and modules:</para>
195<screen><userinput remap="make">make</userinput></screen>
197 <para>If using kernel modules, module configuration in <filename
198 class="directory">/etc/modprobe.d</filename> may be required.
199 Information pertaining to modules and kernel configuration is
200 located in <xref linkend="ch-config-udev"/> and in the kernel
201 documentation in the <filename
202 class="directory">linux-&linux-version;/Documentation</filename> directory.
203 Also, <filename>modprobe.d(5)</filename> may be of interest.</para>
205 <para>Unless module support has been disabled in the kernel configuration,
206 install the modules with:</para>
208<screen><userinput remap="install">make modules_install</userinput></screen>
210 <para>After kernel compilation is complete, additional steps are
211 required to complete the installation. Some files need to be copied to
212 the <filename class="directory">/boot</filename> directory.</para>
214 <caution>
215 <para>If the host system has a separate /boot partition, the files copied
216 below should go there. The easiest way to do that is to bind /boot on the
217 host (outside chroot) to /mnt/lfs/boot before proceeding. As the root
218 user in the <emphasis>host system</emphasis>:</para>
220<screen role="nodump"><userinput>mount --bind /boot /mnt/lfs/boot</userinput></screen>
221 </caution>
223 <para>The path to the kernel image may vary depending on the platform being
224 used. The filename below can be changed to suit your taste, but the stem of
225 the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
226 the automatic setup of the boot process described in the next section. The
227 following command assumes an x86 architecture:</para>
229<screen revision="sysv"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
231<screen revision="systemd"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&versiond;</userinput></screen>
233 <para><filename></filename> is a symbol file for the kernel.
234 It maps the function entry points of every function in the kernel API,
235 as well as the addresses of the kernel data structures for the running
236 kernel. It is used as a resource when investigating kernel problems.
237 Issue the following command to install the map file:</para>
239<screen><userinput remap="install">cp -iv /boot/;</userinput></screen>
241 <para>The kernel configuration file <filename>.config</filename>
242 produced by the <command>make menuconfig</command> step
243 above contains all the configuration selections for the kernel
244 that was just compiled. It is a good idea to keep this file for future
245 reference:</para>
247<screen><userinput remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen>
249 <para>Install the documentation for the Linux kernel:</para>
251<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
252cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
254 <para>It is important to note that the files in the kernel source
255 directory are not owned by <emphasis>root</emphasis>. Whenever a
256 package is unpacked as user <emphasis>root</emphasis> (like we did
257 inside chroot), the files have the user and group IDs of whatever
258 they were on the packager's computer. This is usually not a problem
259 for any other package to be installed because the source tree is
260 removed after the installation. However, the Linux source tree is
261 often retained for a long time. Because of this, there is a chance
262 that whatever user ID the packager used will be assigned to somebody
263 on the machine. That person would then have write access to the kernel
264 source.</para>
266 <note>
267 <para>In many cases, the configuration of the kernel will need to be
268 updated for packages that will be installed later in BLFS. Unlike
269 other packages, it is not necessary to remove the kernel source tree
270 after the newly built kernel is installed.</para>
272 <para>If the kernel source tree is going to be retained, run
273 <command>chown -R 0:0</command> on the <filename
274 class="directory">linux-&linux-version;</filename> directory to ensure
275 all files are owned by user <emphasis>root</emphasis>.</para>
276 </note>
278 <warning>
279 <para>Some kernel documentation recommends creating a symlink from
280 <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
281 source directory. This is specific to kernels prior to the 2.6 series and
282 <emphasis>must not</emphasis> be created on an LFS system as it can cause
283 problems for packages you may wish to build once your base LFS system is
284 complete.</para>
285 </warning>
287 <warning>
288 <para>The headers in the system's <filename
289 class="directory">include</filename> directory (<filename
290 class="directory">/usr/include</filename>) should
291 <emphasis>always</emphasis> be the ones against which Glibc was compiled,
292 that is, the sanitised headers installed in <xref
293 linkend="ch-tools-linux-headers"/>. Therefore, they should
294 <emphasis>never</emphasis> be replaced by either the raw kernel headers
295 or any other kernel sanitized headers.</para>
296 </warning>
298 </sect2>
300 <sect2 id="conf-modprobe" role="configuration">
301 <title>Configuring Linux Module Load Order</title>
303 <indexterm zone="conf-modprobe">
304 <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
305 </indexterm>
307 <para>Most of the time Linux modules are loaded automatically, but
308 sometimes it needs some specific direction. The program that loads
309 modules, <command>modprobe</command> or <command>insmod</command>, uses
310 <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
311 needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
312 uhci_hcd) have been built as modules, they will be loaded in the correct
313 order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
314 to avoid a warning being output at boot time.</para>
316 <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
317 the following:</para>
319<screen><userinput>install -v -m755 -d /etc/modprobe.d
320cat &gt; /etc/modprobe.d/usb.conf &lt;&lt; "EOF"
321<literal># Begin /etc/modprobe.d/usb.conf
323install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
324install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
326# End /etc/modprobe.d/usb.conf</literal>
329 </sect2>
331 <sect2 id="contents-kernel" role="content">
332 <title>Contents of Linux</title>
334 <segmentedlist>
335 <segtitle>Installed files</segtitle>
336 <segtitle>Installed directories</segtitle>
338 <seglistitem>
339 <seg>config-&linux-version;,
340 <phrase revision="sysv">vmlinuz-&linux-version;-lfs-&version;,</phrase>
341 <phrase revision="systemd">vmlinuz-&linux-version;-lfs-&versiond;,</phrase>
342 and;</seg>
343 <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
344 </seglistitem>
345 </segmentedlist>
347 <variablelist>
348 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
349 <?dbfo list-presentation="list"?>
350 <?dbhtml list-presentation="table"?>
352 <varlistentry id="config">
353 <term><filename>config-&linux-version;</filename></term>
354 <listitem>
355 <para>Contains all the configuration selections for the kernel</para>
356 <indexterm zone="ch-bootable-kernel config">
357 <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
358 </indexterm>
359 </listitem>
360 </varlistentry>
362 <varlistentry id="lfskernel">
363 <term revision="sysv"><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term>
364 <term revision="systemd"><filename>vmlinuz-&linux-version;-lfs-&versiond;</filename></term>
365 <listitem>
366 <para>The engine of the Linux system. When turning on the computer,
367 the kernel is the first part of the operating system that gets loaded.
368 It detects and initializes all components of the computer's hardware,
369 then makes these components available as a tree of files to the
370 software and turns a single CPU into a multitasking machine capable
371 of running scores of programs seemingly at the same time</para>
372 <indexterm zone="ch-bootable-kernel lfskernel">
373 <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
374 </indexterm>
375 </listitem>
376 </varlistentry>
378 <varlistentry id="">
379 <term><filename>;</filename></term>
380 <listitem>
381 <para>A list of addresses and symbols; it maps the entry points and
382 addresses of all the functions and data structures in the
383 kernel</para>
384 <indexterm zone="ch-bootable-kernel">
385 <primary sortas="e-/boot/">/boot/;</primary>
386 </indexterm>
387 </listitem>
388 </varlistentry>
390 </variablelist>
392 </sect2>
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