source: chapter10/kernel.xml@ 8b0e9795

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Last change on this file since 8b0e9795 was 8b0e9795, checked in by Xi Ruoyao <xry111@…>, 3 years ago

kernel: don't force frame pointer unwinder for sysv, and remove an empty line in sysd

git-svn-id: 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

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File size: 16.8 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 <!-- Support for compiling a keymap into the kernel is deliberately removed -->
59 <para>Configure the kernel via a menu-driven interface. For general
60 information on kernel configuration see <ulink
61 url="&hints-root;kernel-configuration.txt"/>. BLFS has some information
62 regarding particular kernel configuration requirements of packages outside
63 of LFS at <ulink
64 url="&blfs-book;longindex.html#kernel-config-index"/>. Additional
65 information about configuring and building the kernel can be found at
66 <ulink url=""/> </para>
68 <note>
70 <para>A good starting place for setting up the kernel configuration is to
71 run <command>make defconfig</command>. This will set the base
72 configuration to a good state that takes your current system architecture
73 into account.</para>
75 <para>Be sure to enable/disable/set the following features or the system might
76 not work correctly or boot at all:</para>
78 <screen role="nodump" revision="sysv">
79Device Drivers ---&gt;
80 Generic Driver Options ---&gt;
81 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
82 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]</screen>
84 <screen role="nodump" revision="systemd">General setup -->
85 [*] Control Group support [CONFIG_CGROUPS]
86 [ ] Enable deprecated sysfs features to support old userspace tools [CONFIG_SYSFS_DEPRECATED]
87 [*] Configure standard kernel features (expert users) [CONFIG_EXPERT] ---&gt;
88 [*] open by fhandle syscalls [CONFIG_FHANDLE]
89 [ ] Auditing support [CONFIG_AUDIT]
90Processor type and features ---&gt;
91 [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP]
92Firmware Drivers ---&gt;
93 [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID]
94Networking support ---&gt;
95 Networking options ---&gt;
96 &lt;*&gt; The IPv6 protocol [CONFIG_IPV6]
97Device Drivers ---&gt;
98 Generic Driver Options ---&gt;
99 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
100 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
101 Firmware Loader ---&gt;
102 [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER]
103File systems ---&gt;
104 [*] Inotify support for userspace [CONFIG_INOTIFY_USER]
105 &lt;*&gt; Kernel automounter support (supports v3, v4, and v5) [CONFIG_AUTOFS_FS]
106 Pseudo filesystems ---&gt;
107 [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL]
108 [*] Tmpfs extended attributes [CONFIG_TMPFS_XATTR]</screen>
109 </note>
111 <note revision="systemd">
112 <para>While "The IPv6 Protocol" is not strictly
113 required, it is highly recommended by the systemd developers.</para>
114 </note>
116 <para revision="sysv">There are several other options that may be desired
117 depending on the requirements for the system. For a list of options needed
118 for BLFS packages, see the <ulink
119 url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS
120 Index of Kernel Settings</ulink>
121 (&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index).</para>
123 <note>
124 <para>If your host hardware is using UEFI, then the 'make defconfig'
125 above should automatically add in some EFI-related kernel options.</para>
127 <para>In order to allow your LFS kernel to be booted from within your
128 host's UEFI boot environment, your kernel must have this option
129 selected:</para>
131<screen role="nodump">Processor type and features ---&gt;
132 [*] EFI stub support [CONFIG_EFI_STUB]</screen>
134 <para>A fuller description of managing UEFI environments from within LFS
135 is covered by the lfs-uefi.txt hint at
136 <ulink
137 url="&hints-root;lfs-uefi.txt"/>.
138 </para>
139 </note>
141 <variablelist>
142 <title>The rationale for the above configuration items:</title>
144 <varlistentry>
145 <term><parameter>Support for uevent helper</parameter></term>
146 <listitem>
147 <para>Having this option set may interfere with device
148 management when using Udev/Eudev. </para>
149 </listitem>
150 </varlistentry>
152 <varlistentry>
153 <term><parameter>Maintain a devtmpfs</parameter></term>
154 <listitem>
155 <para>This will create automated device nodes which are populated by the
156 kernel, even without Udev running. Udev then runs on top of this,
157 managing permissions and adding symlinks. This configuration
158 item is required for all users of Udev/Eudev.</para>
159 </listitem>
160 </varlistentry>
162 </variablelist>
164<screen role="nodump"><userinput>make menuconfig</userinput></screen>
166 <variablelist>
167 <title>The meaning of optional make environment variables:</title>
169 <varlistentry>
170 <term><parameter>LANG=&lt;host_LANG_value&gt; LC_ALL=</parameter></term>
171 <listitem>
172 <para>This establishes the locale setting to the one used on the
173 host. This may be needed for a proper menuconfig ncurses interface
174 line drawing on a UTF-8 linux text console.</para>
176 <para>If used, be sure to replace
177 <replaceable>&lt;host_LANG_value&gt;</replaceable> by the value of
178 the <envar>$LANG</envar> variable from your host. You can
179 alternatively use instead the host's value of <envar>$LC_ALL</envar>
180 or <envar>$LC_CTYPE</envar>.</para>
181 </listitem>
182 </varlistentry>
184 </variablelist>
186 <para>Alternatively, <command>make oldconfig</command> may be more
187 appropriate in some situations. See the <filename>README</filename>
188 file for more information.</para>
190 <para>If desired, skip kernel configuration by copying the kernel
191 config file, <filename>.config</filename>, from the host system
192 (assuming it is available) to the unpacked <filename
193 class="directory">linux-&linux-version;</filename> directory. However,
194 we do not recommend this option. It is often better to explore all the
195 configuration menus and create the kernel configuration from
196 scratch.</para>
198 <para>Compile the kernel image and modules:</para>
200<screen><userinput remap="make">make</userinput></screen>
202 <para>If using kernel modules, module configuration in <filename
203 class="directory">/etc/modprobe.d</filename> may be required.
204 Information pertaining to modules and kernel configuration is
205 located in <xref linkend="ch-config-udev"/> and in the kernel
206 documentation in the <filename
207 class="directory">linux-&linux-version;/Documentation</filename> directory.
208 Also, <filename>modprobe.d(5)</filename> may be of interest.</para>
210 <para>Unless module support has been disabled in the kernel configuration,
211 install the modules with:</para>
213<screen><userinput remap="install">make modules_install</userinput></screen>
215 <para>After kernel compilation is complete, additional steps are
216 required to complete the installation. Some files need to be copied to
217 the <filename class="directory">/boot</filename> directory.</para>
219 <caution>
220 <para>If the host system has a separate /boot partition, the files copied
221 below should go there. The easiest way to do that is to bind /boot on the
222 host (outside chroot) to /mnt/lfs/boot before proceeding. As the root
223 user in the <emphasis>host system</emphasis>:</para>
225<screen role="nodump"><userinput>mount --bind /boot /mnt/lfs/boot</userinput></screen>
226 </caution>
228 <para>The path to the kernel image may vary depending on the platform being
229 used. The filename below can be changed to suit your taste, but the stem of
230 the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
231 the automatic setup of the boot process described in the next section. The
232 following command assumes an x86 architecture:</para>
234<screen revision="sysv"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
236<screen revision="systemd"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&versiond;</userinput></screen>
238 <para><filename></filename> is a symbol file for the kernel.
239 It maps the function entry points of every function in the kernel API,
240 as well as the addresses of the kernel data structures for the running
241 kernel. It is used as a resource when investigating kernel problems.
242 Issue the following command to install the map file:</para>
244<screen><userinput remap="install">cp -iv /boot/;</userinput></screen>
246 <para>The kernel configuration file <filename>.config</filename>
247 produced by the <command>make menuconfig</command> step
248 above contains all the configuration selections for the kernel
249 that was just compiled. It is a good idea to keep this file for future
250 reference:</para>
252<screen><userinput remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen>
254 <para>Install the documentation for the Linux kernel:</para>
256<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
257cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
259 <para>It is important to note that the files in the kernel source
260 directory are not owned by <emphasis>root</emphasis>. Whenever a
261 package is unpacked as user <emphasis>root</emphasis> (like we did
262 inside chroot), the files have the user and group IDs of whatever
263 they were on the packager's computer. This is usually not a problem
264 for any other package to be installed because the source tree is
265 removed after the installation. However, the Linux source tree is
266 often retained for a long time. Because of this, there is a chance
267 that whatever user ID the packager used will be assigned to somebody
268 on the machine. That person would then have write access to the kernel
269 source.</para>
271 <note>
272 <para>In many cases, the configuration of the kernel will need to be
273 updated for packages that will be installed later in BLFS. Unlike
274 other packages, it is not necessary to remove the kernel source tree
275 after the newly built kernel is installed.</para>
277 <para>If the kernel source tree is going to be retained, run
278 <command>chown -R 0:0</command> on the <filename
279 class="directory">linux-&linux-version;</filename> directory to ensure
280 all files are owned by user <emphasis>root</emphasis>.</para>
281 </note>
283 <warning>
284 <para>Some kernel documentation recommends creating a symlink from
285 <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
286 source directory. This is specific to kernels prior to the 2.6 series and
287 <emphasis>must not</emphasis> be created on an LFS system as it can cause
288 problems for packages you may wish to build once your base LFS system is
289 complete.</para>
290 </warning>
292 <warning>
293 <para>The headers in the system's <filename
294 class="directory">include</filename> directory (<filename
295 class="directory">/usr/include</filename>) should
296 <emphasis>always</emphasis> be the ones against which Glibc was compiled,
297 that is, the sanitised headers installed in <xref
298 linkend="ch-tools-linux-headers"/>. Therefore, they should
299 <emphasis>never</emphasis> be replaced by either the raw kernel headers
300 or any other kernel sanitized headers.</para>
301 </warning>
303 </sect2>
305 <sect2 id="conf-modprobe" role="configuration">
306 <title>Configuring Linux Module Load Order</title>
308 <indexterm zone="conf-modprobe">
309 <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
310 </indexterm>
312 <para>Most of the time Linux modules are loaded automatically, but
313 sometimes it needs some specific direction. The program that loads
314 modules, <command>modprobe</command> or <command>insmod</command>, uses
315 <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
316 needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
317 uhci_hcd) have been built as modules, they will be loaded in the correct
318 order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
319 to avoid a warning being output at boot time.</para>
321 <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
322 the following:</para>
324<screen><userinput>install -v -m755 -d /etc/modprobe.d
325cat &gt; /etc/modprobe.d/usb.conf &lt;&lt; "EOF"
326<literal># Begin /etc/modprobe.d/usb.conf
328install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
329install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
331# End /etc/modprobe.d/usb.conf</literal>
334 </sect2>
336 <sect2 id="contents-kernel" role="content">
337 <title>Contents of Linux</title>
339 <segmentedlist>
340 <segtitle>Installed files</segtitle>
341 <segtitle>Installed directories</segtitle>
343 <seglistitem>
344 <seg>config-&linux-version;,
345 <phrase revision="sysv">vmlinuz-&linux-version;-lfs-&version;,</phrase>
346 <phrase revision="systemd">vmlinuz-&linux-version;-lfs-&versiond;,</phrase>
347 and;</seg>
348 <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
349 </seglistitem>
350 </segmentedlist>
352 <variablelist>
353 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
354 <?dbfo list-presentation="list"?>
355 <?dbhtml list-presentation="table"?>
357 <varlistentry id="config">
358 <term><filename>config-&linux-version;</filename></term>
359 <listitem>
360 <para>Contains all the configuration selections for the kernel</para>
361 <indexterm zone="ch-bootable-kernel config">
362 <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
363 </indexterm>
364 </listitem>
365 </varlistentry>
367 <varlistentry id="lfskernel">
368 <term revision="sysv"><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term>
369 <term revision="systemd"><filename>vmlinuz-&linux-version;-lfs-&versiond;</filename></term>
370 <listitem>
371 <para>The engine of the Linux system. When turning on the computer,
372 the kernel is the first part of the operating system that gets loaded.
373 It detects and initializes all components of the computer's hardware,
374 then makes these components available as a tree of files to the
375 software and turns a single CPU into a multitasking machine capable
376 of running scores of programs seemingly at the same time</para>
377 <indexterm zone="ch-bootable-kernel lfskernel">
378 <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
379 </indexterm>
380 </listitem>
381 </varlistentry>
383 <varlistentry id="">
384 <term><filename>;</filename></term>
385 <listitem>
386 <para>A list of addresses and symbols; it maps the entry points and
387 addresses of all the functions and data structures in the
388 kernel</para>
389 <indexterm zone="ch-bootable-kernel">
390 <primary sortas="e-/boot/">/boot/;</primary>
391 </indexterm>
392 </listitem>
393 </varlistentry>
395 </variablelist>
397 </sect2>
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