source: chapter10/kernel.xml@ 53beb36

multilib
Last change on this file since 53beb36 was 53beb36, checked in by Thomas Trepl (Moody) <thomas@…>, 2 years ago

Automatic merge of trunk into multilib

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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">General setup -->
109 &lt; &gt; Enable kernel headers through /sys/kernel/kheaders.tar.xz [CONFIG_IKHEADERS]
110Device Drivers ---&gt;
111 Graphics support ---&gt;
112 Frame buffer Devices ---&gt;
113 [*] Support for frame buffer devices ----
114 Generic Driver Options ---&gt;
115 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
116 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]</screen>
117
118 <screen role="nodump" revision="systemd">General setup -->
119 [ ] Auditing Support [CONFIG_AUDIT]
120 &lt; &gt; Enable kernel headers through /sys/kernel/kheaders.tar.xz [CONFIG_IKHEADERS]
121 [*] Control Group support [CONFIG_CGROUPS] ---&gt;
122 [*] Memory controller [CONFIG_MEMCG]
123 [ ] Enable deprecated sysfs features to support old userspace tools [CONFIG_SYSFS_DEPRECATED]
124 [*] Configure standard kernel features (expert users) [CONFIG_EXPERT] ---&gt;
125 [*] open by fhandle syscalls [CONFIG_FHANDLE]
126 CPU/Task time and stats accounting ---&gt;
127 [*] Pressure stall information tracking [CONFIG_PSI]
128General architecture-dependent options ---&gt;
129 [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP]
130Networking support ---&gt;
131 Networking options ---&gt;
132 &lt;*&gt; The IPv6 protocol [CONFIG_IPV6]
133Device Drivers ---&gt;
134 Firmware Drivers ---&gt;
135 [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID]
136 Graphics support ---&gt;
137 Frame buffer Devices ---&gt;
138 [*] Support for frame buffer devices ----
139 Generic Driver Options ---&gt;
140 [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
141 [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
142 Firmware Loader ---&gt;
143 [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER]
144File systems ---&gt;
145 [*] Inotify support for userspace [CONFIG_INOTIFY_USER]
146 Pseudo filesystems ---&gt;
147 [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL]</screen>
148 </note>
149
150 <note revision="systemd">
151 <para>While "The IPv6 Protocol" is not strictly
152 required, it is highly recommended by the systemd developers.</para>
153 </note>
154
155 <para revision="sysv">There are several other options that may be desired
156 depending on the requirements for the system. For a list of options needed
157 for BLFS packages, see the <ulink
158 url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS
159 Index of Kernel Settings</ulink>
160 (&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index).</para>
161
162 <note>
163 <para>If your host hardware is using UEFI and you wish to boot the
164 LFS system with it, you should adjust some kernel configuration
165 following <ulink url="&blfs-book;postlfs/grub-setup.html#uefi-kernel">
166 the BLFS page</ulink>.</para>
167 </note>
168
169 <note arch="ml_32,ml_x32,ml_all">
170 <para>
171 The kernel on a multilib system needs to be able to
172 identify and start binaries compiled for different architectures
173 than the default.
174 </para>
175
176 <para arch="ml_32,ml_all">
177 If support for any 32bit ABI was built, make sure that the option
178 "IA32 Emulation" is selected. The option 'IA32 a.out support' is
179 optional.
180 </para>
181
182 <para arch="ml_x32,ml_all">
183 If support for the x32bit ABI was built, make sure that the option
184 "x32 ABI for 64-bit mode" is selected.
185 </para>
186
187<screen arch="ml_32">Binary Emulations ---&gt;
188 [*] IA32 Emulation [CONFIG_IA32_EMULATION]
189 &lt;M&gt; IA32 a.out support [CONFIG_IA32_AOUT]
190</screen>
191<screen arch="ml_x32">Binary Emulations ---&gt;
192 [*] x32 ABI for 64-bit mode [CONFIG_X86_X32]
193</screen>
194<screen arch="ml_all">Binary Emulations ---&gt;
195 [*] IA32 Emulation [CONFIG_IA32_EMULATION]
196 &lt;M&gt; IA32 a.out support [CONFIG_IA32_AOUT]
197 [*] x32 ABI for 64-bit mode [CONFIG_X86_X32]
198</screen>
199 </note>
200
201 <variablelist>
202 <title>The rationale for the above configuration items:</title>
203
204 <varlistentry>
205 <term>
206 <parameter>
207 Enable kernel headers through /sys/kernel/kheaders.tar.xz
208 </parameter>
209 </term>
210 <listitem>
211 <para>This will require <command>cpio</command> building the kernel.
212 <command>cpio</command> is not installed by LFS.</para>
213 </listitem>
214 </varlistentry>
215
216 <varlistentry>
217 <term><parameter>Support for uevent helper</parameter></term>
218 <listitem>
219 <para>Having this option set may interfere with device
220 management when using Udev/Eudev. </para>
221 </listitem>
222 </varlistentry>
223
224 <varlistentry>
225 <term><parameter>Maintain a devtmpfs</parameter></term>
226 <listitem>
227 <para>This will create automated device nodes which are populated by the
228 kernel, even without Udev running. Udev then runs on top of this,
229 managing permissions and adding symlinks. This configuration
230 item is required for all users of Udev/Eudev.</para>
231 </listitem>
232 </varlistentry>
233
234 </variablelist>
235
236 <para>Alternatively, <command>make oldconfig</command> may be more
237 appropriate in some situations. See the <filename>README</filename>
238 file for more information.</para>
239
240 <para>If desired, skip kernel configuration by copying the kernel
241 config file, <filename>.config</filename>, from the host system
242 (assuming it is available) to the unpacked <filename
243 class="directory">linux-&linux-version;</filename> directory. However,
244 we do not recommend this option. It is often better to explore all the
245 configuration menus and create the kernel configuration from
246 scratch.</para>
247
248 <para>Compile the kernel image and modules:</para>
249
250<screen><userinput remap="make">make</userinput></screen>
251
252 <para>If using kernel modules, module configuration in <filename
253 class="directory">/etc/modprobe.d</filename> may be required.
254 Information pertaining to modules and kernel configuration is
255 located in <xref linkend="ch-config-udev"/> and in the kernel
256 documentation in the <filename
257 class="directory">linux-&linux-version;/Documentation</filename> directory.
258 Also, <filename>modprobe.d(5)</filename> may be of interest.</para>
259
260 <para>Unless module support has been disabled in the kernel configuration,
261 install the modules with:</para>
262
263<screen><userinput remap="install">make modules_install</userinput></screen>
264
265 <para>After kernel compilation is complete, additional steps are
266 required to complete the installation. Some files need to be copied to
267 the <filename class="directory">/boot</filename> directory.</para>
268
269 <caution>
270 <para>If the host system has a separate /boot partition, the files copied
271 below should go there. The easiest way to do that is to bind /boot on the
272 host (outside chroot) to /mnt/lfs/boot before proceeding. As the root
273 user in the <emphasis>host system</emphasis>:</para>
274
275<screen role="nodump"><userinput>mount --bind /boot /mnt/lfs/boot</userinput></screen>
276 </caution>
277
278 <para>The path to the kernel image may vary depending on the platform being
279 used. The filename below can be changed to suit your taste, but the stem of
280 the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
281 the automatic setup of the boot process described in the next section. The
282 following command assumes an x86 architecture:</para>
283
284<screen><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
285
286 <para><filename>System.map</filename> is a symbol file for the kernel.
287 It maps the function entry points of every function in the kernel API,
288 as well as the addresses of the kernel data structures for the running
289 kernel. It is used as a resource when investigating kernel problems.
290 Issue the following command to install the map file:</para>
291
292<screen><userinput remap="install">cp -iv System.map /boot/System.map-&linux-version;</userinput></screen>
293
294 <para>The kernel configuration file <filename>.config</filename>
295 produced by the <command>make menuconfig</command> step
296 above contains all the configuration selections for the kernel
297 that was just compiled. It is a good idea to keep this file for future
298 reference:</para>
299
300<screen><userinput remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen>
301
302 <para>Install the documentation for the Linux kernel:</para>
303
304<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
305cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
306
307 <para>It is important to note that the files in the kernel source
308 directory are not owned by <emphasis>root</emphasis>. Whenever a
309 package is unpacked as user <emphasis>root</emphasis> (like we did
310 inside chroot), the files have the user and group IDs of whatever
311 they were on the packager's computer. This is usually not a problem
312 for any other package to be installed because the source tree is
313 removed after the installation. However, the Linux source tree is
314 often retained for a long time. Because of this, there is a chance
315 that whatever user ID the packager used will be assigned to somebody
316 on the machine. That person would then have write access to the kernel
317 source.</para>
318
319 <note>
320 <para>In many cases, the configuration of the kernel will need to be
321 updated for packages that will be installed later in BLFS. Unlike
322 other packages, it is not necessary to remove the kernel source tree
323 after the newly built kernel is installed.</para>
324
325 <para>If the kernel source tree is going to be retained, run
326 <command>chown -R 0:0</command> on the <filename
327 class="directory">linux-&linux-version;</filename> directory to ensure
328 all files are owned by user <emphasis>root</emphasis>.</para>
329 </note>
330
331 <warning>
332 <para>Some kernel documentation recommends creating a symlink from
333 <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
334 source directory. This is specific to kernels prior to the 2.6 series and
335 <emphasis>must not</emphasis> be created on an LFS system as it can cause
336 problems for packages you may wish to build once your base LFS system is
337 complete.</para>
338 </warning>
339
340 <warning>
341 <para>The headers in the system's <filename
342 class="directory">include</filename> directory (<filename
343 class="directory">/usr/include</filename>) should
344 <emphasis>always</emphasis> be the ones against which Glibc was compiled,
345 that is, the sanitised headers installed in <xref
346 linkend="ch-tools-linux-headers"/>. Therefore, they should
347 <emphasis>never</emphasis> be replaced by either the raw kernel headers
348 or any other kernel sanitized headers.</para>
349 </warning>
350
351 </sect2>
352
353 <sect2 id="conf-modprobe" role="configuration">
354 <title>Configuring Linux Module Load Order</title>
355
356 <indexterm zone="conf-modprobe">
357 <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
358 </indexterm>
359
360 <para>Most of the time Linux modules are loaded automatically, but
361 sometimes it needs some specific direction. The program that loads
362 modules, <command>modprobe</command> or <command>insmod</command>, uses
363 <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
364 needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
365 uhci_hcd) have been built as modules, they will be loaded in the correct
366 order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
367 to avoid a warning being output at boot time.</para>
368
369 <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
370 the following:</para>
371
372<screen><userinput>install -v -m755 -d /etc/modprobe.d
373cat &gt; /etc/modprobe.d/usb.conf &lt;&lt; "EOF"
374<literal># Begin /etc/modprobe.d/usb.conf
375
376install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
377install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
378
379# End /etc/modprobe.d/usb.conf</literal>
380EOF</userinput></screen>
381
382 </sect2>
383
384 <sect2 id="contents-kernel" role="content">
385 <title>Contents of Linux</title>
386
387 <segmentedlist>
388 <segtitle>Installed files</segtitle>
389 <segtitle>Installed directories</segtitle>
390
391 <seglistitem>
392 <seg>config-&linux-version;,
393 vmlinuz-&linux-version;-lfs-&version;,
394 and System.map-&linux-version;</seg>
395 <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
396 </seglistitem>
397 </segmentedlist>
398
399 <variablelist>
400 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
401 <?dbfo list-presentation="list"?>
402 <?dbhtml list-presentation="table"?>
403
404 <varlistentry id="config">
405 <term><filename>config-&linux-version;</filename></term>
406 <listitem>
407 <para>Contains all the configuration selections for the kernel</para>
408 <indexterm zone="ch-bootable-kernel config">
409 <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
410 </indexterm>
411 </listitem>
412 </varlistentry>
413
414 <varlistentry id="lfskernel">
415 <term><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term>
416 <listitem>
417 <para>The engine of the Linux system. When turning on the computer,
418 the kernel is the first part of the operating system that gets loaded.
419 It detects and initializes all components of the computer's hardware,
420 then makes these components available as a tree of files to the
421 software and turns a single CPU into a multitasking machine capable
422 of running scores of programs seemingly at the same time</para>
423 <indexterm zone="ch-bootable-kernel lfskernel">
424 <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
425 </indexterm>
426 </listitem>
427 </varlistentry>
428
429 <varlistentry id="System.map">
430 <term><filename>System.map-&linux-version;</filename></term>
431 <listitem>
432 <para>A list of addresses and symbols; it maps the entry points and
433 addresses of all the functions and data structures in the
434 kernel</para>
435 <indexterm zone="ch-bootable-kernel System.map">
436 <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
437 </indexterm>
438 </listitem>
439 </varlistentry>
440
441 </variablelist>
442
443 </sect2>
444
445</sect1>
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