[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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[b78c747] | 7 |
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[81fd230] | 8 | <sect1 id="ch-bootable-kernel" role="wrap">
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[b78c747] | 9 | <?dbhtml filename="kernel.html"?>
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| 10 |
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[e747759] | 11 | <sect1info condition="script">
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| 12 | <productname>linux</productname>
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| 13 | <productnumber>&linux-version;</productnumber>
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| 14 | <address>&linux-url;</address>
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| 15 | </sect1info>
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| 16 |
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[b78c747] | 17 | <title>Linux-&linux-version;</title>
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| 18 |
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| 19 | <indexterm zone="ch-bootable-kernel">
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| 20 | <primary sortas="a-Linux">Linux</primary>
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| 21 | </indexterm>
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| 22 |
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| 23 | <sect2 role="package">
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| 24 | <title/>
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| 25 |
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| 26 | <para>The Linux package contains the Linux kernel.</para>
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[673b0d8] | 27 |
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[b78c747] | 28 | <segmentedlist>
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| 29 | <segtitle>&buildtime;</segtitle>
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| 30 | <segtitle>&diskspace;</segtitle>
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[6370fa6] | 31 |
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[b78c747] | 32 | <seglistitem>
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[e4a5635] | 33 | <seg>&linux-ch8-sbu;</seg>
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| 34 | <seg>&linux-ch8-du;</seg>
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[b78c747] | 35 | </seglistitem>
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| 36 | </segmentedlist>
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[a001133] | 37 |
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[b78c747] | 38 | </sect2>
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[2081905] | 39 |
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[b78c747] | 40 | <sect2 role="installation">
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| 41 | <title>Installation of the kernel</title>
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[81fd230] | 42 |
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[b78c747] | 43 | <para>Building the kernel involves a few steps—configuration,
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| 44 | compilation, and installation. Read the <filename>README</filename> file
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| 45 | in the kernel source tree for alternative methods to the way this book
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| 46 | configures the kernel.</para>
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| 47 |
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| 48 | <para>Prepare for compilation by running the following command:</para>
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[b9e738a] | 49 |
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[0445a3d] | 50 | <screen><userinput remap="pre">make mrproper</userinput></screen>
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[b9e738a] | 51 |
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[b78c747] | 52 | <para>This ensures that the kernel tree is absolutely clean. The
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| 53 | kernel team recommends that this command be issued prior to each
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| 54 | kernel compilation. Do not rely on the source tree being clean after
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| 55 | un-tarring.</para>
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[d72e04a] | 56 |
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[fa21b3d] | 57 | <!-- Support for compiling a keymap into the kernel is deliberately removed -->
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[81fd230] | 58 |
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[764b5cf] | 59 | <para>Configure the kernel via a menu-driven interface. For general
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| 60 | information on kernel configuration see <ulink
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[e9ba8aa8] | 61 | url="&hints-root;kernel-configuration.txt"/>. BLFS has some information
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[764b5cf] | 62 | regarding particular kernel configuration requirements of packages outside
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| 63 | of LFS at <ulink
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[e9ba8aa8] | 64 | url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>. </para>
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| 65 |
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| 66 | <note><para>Due to recent changes in <application>udev</application>, be sure to
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| 67 | select:</para>
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[2ca8941] | 68 |
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[e9ba8aa8] | 69 | <screen role="nodump">Device Drivers --->
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| 70 | Generic Driver Options --->
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| 71 | Maintain a devtmpfs filesystem to mount at /dev</screen></note>
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[2081905] | 72 |
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[2ccccf7] | 73 | <screen role="nodump"><userinput>make LANG=<replaceable><host_LANG_value></replaceable> LC_ALL= menuconfig</userinput></screen>
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| 74 |
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| 75 | <variablelist>
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| 76 | <title>The meaning of the make parameters:</title>
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| 77 |
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| 78 | <varlistentry>
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| 79 | <term><parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term>
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| 80 | <listitem>
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| 81 | <para>This establishes the locale setting to the one used on the host.
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| 82 | This is needed for a proper menuconfig ncurses interface line
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| 83 | drawing on UTF-8 linux text console.</para>
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| 84 |
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| 85 | <para>Be sure to replace <replaceable><host_LANG_value></replaceable>
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| 86 | by the value of the <envar>$LANG</envar> variable from your host.
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[01670aad] | 87 | If not set, you could use instead the host's value of <envar>$LC_ALL</envar>
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[2ccccf7] | 88 | or <envar>$LC_CTYPE</envar>.</para>
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| 89 | </listitem>
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| 90 | </varlistentry>
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| 91 |
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| 92 | </variablelist>
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[2081905] | 93 |
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[b78c747] | 94 | <para>Alternatively, <command>make oldconfig</command> may be more
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| 95 | appropriate in some situations. See the <filename>README</filename>
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| 96 | file for more information.</para>
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| 97 |
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| 98 | <para>If desired, skip kernel configuration by copying the kernel
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| 99 | config file, <filename>.config</filename>, from the host system
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| 100 | (assuming it is available) to the unpacked <filename
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| 101 | class="directory">linux-&linux-version;</filename> directory. However,
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| 102 | we do not recommend this option. It is often better to explore all the
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| 103 | configuration menus and create the kernel configuration from
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| 104 | scratch.</para>
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| 105 |
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| 106 | <para>Compile the kernel image and modules:</para>
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[2081905] | 107 |
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[0445a3d] | 108 | <screen><userinput remap="make">make</userinput></screen>
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[2081905] | 109 |
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[b67f2d6] | 110 | <para>If using kernel modules, module configuration in <filename
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| 111 | class="directory">/etc/modprobe.d</filename> may be required.
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| 112 | Information pertaining to modules and kernel configuration is
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| 113 | located in <xref linkend="ch-scripts-udev"/> and in the kernel
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| 114 | documentation in the <filename
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[b78c747] | 115 | class="directory">linux-&linux-version;/Documentation</filename> directory.
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| 116 | Also, <filename>modprobe.conf(5)</filename> may be of interest.</para>
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[4b59d59] | 117 |
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[b78c747] | 118 | <para>Install the modules, if the kernel configuration uses them:</para>
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[2081905] | 119 |
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[0445a3d] | 120 | <screen><userinput remap="install">make modules_install</userinput></screen>
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[2081905] | 121 |
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[b78c747] | 122 | <para>After kernel compilation is complete, additional steps are
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| 123 | required to complete the installation. Some files need to be copied to
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| 124 | the <filename class="directory">/boot</filename> directory.</para>
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[81fd230] | 125 |
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[f9bcaec] | 126 | <para>The path to the kernel image may vary depending on the platform being
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| 127 | used. The filename below can be changed to suit your taste, but the stem of
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[fe1643e] | 128 | the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
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[f9bcaec] | 129 | the automatic setup of the boot process described in the next section. The
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| 130 | following command assumes an x86 architecture:</para>
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[2081905] | 131 |
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[fe1643e] | 132 | <screen><userinput remap="install">cp -v arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
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[2081905] | 133 |
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[b78c747] | 134 | <para><filename>System.map</filename> is a symbol file for the kernel.
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| 135 | It maps the function entry points of every function in the kernel API,
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| 136 | as well as the addresses of the kernel data structures for the running
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[2ca8941] | 137 | kernel. It is used as a resource when investigating kernel problems.
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[6028823] | 138 | Issue the following command to install the map file:</para>
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[81fd230] | 139 |
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[0445a3d] | 140 | <screen><userinput remap="install">cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
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[2081905] | 141 |
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[b78c747] | 142 | <para>The kernel configuration file <filename>.config</filename>
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| 143 | produced by the <command>make menuconfig</command> step
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| 144 | above contains all the configuration selections for the kernel
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| 145 | that was just compiled. It is a good idea to keep this file for future
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| 146 | reference:</para>
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[81fd230] | 147 |
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[0445a3d] | 148 | <screen><userinput remap="install">cp -v .config /boot/config-&linux-version;</userinput></screen>
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[2081905] | 149 |
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[a1e18fa] | 150 | <para>Install the documentation for the Linux kernel:</para>
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| 151 |
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[0445a3d] | 152 | <screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
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[c226182] | 153 | cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
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[a1e18fa] | 154 |
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[b78c747] | 155 | <para>It is important to note that the files in the kernel source
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| 156 | directory are not owned by <emphasis>root</emphasis>. Whenever a
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| 157 | package is unpacked as user <emphasis>root</emphasis> (like we did
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| 158 | inside chroot), the files have the user and group IDs of whatever
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| 159 | they were on the packager's computer. This is usually not a problem
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| 160 | for any other package to be installed because the source tree is
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| 161 | removed after the installation. However, the Linux source tree is
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| 162 | often retained for a long time. Because of this, there is a chance
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| 163 | that whatever user ID the packager used will be assigned to somebody
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| 164 | on the machine. That person would then have write access to the kernel
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| 165 | source.</para>
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| 166 |
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| 167 | <para>If the kernel source tree is going to be retained, run
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| 168 | <command>chown -R 0:0</command> on the <filename
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| 169 | class="directory">linux-&linux-version;</filename> directory to ensure
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| 170 | all files are owned by user <emphasis>root</emphasis>.</para>
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| 171 |
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| 172 | <warning>
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| 173 | <para>Some kernel documentation recommends creating a symlink from
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| 174 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
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| 175 | source directory. This is specific to kernels prior to the 2.6 series and
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| 176 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
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| 177 | problems for packages you may wish to build once your base LFS system is
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| 178 | complete.</para>
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[6c75ca3] | 179 | </warning>
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[b78c747] | 180 |
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[6c75ca3] | 181 | <warning>
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| 182 | <para>The headers in the system's
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[b78c747] | 183 | <filename class="directory">include</filename> directory should
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| 184 | <emphasis>always</emphasis> be the ones against which Glibc was compiled,
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[2ccccf7] | 185 | that is, the sanitised headers from this Linux kernel tarball.
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[01670aad] | 186 | Therefore, they should <emphasis>never</emphasis> be replaced by either
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[2ccccf7] | 187 | the raw kernel headers or any other kernel sanitized headers.</para>
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[b78c747] | 188 | </warning>
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| 189 |
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| 190 | </sect2>
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| 191 |
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[200e466] | 192 | <sect2 id="conf-modprobe" role="configuration">
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| 193 | <title>Configuring Linux Module Load Order</title>
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| 194 |
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| 195 | <indexterm zone="conf-modprobe">
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[b67f2d6] | 196 | <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
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[200e466] | 197 | </indexterm>
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| 198 |
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[cdd87ad] | 199 | <para>Most of the time Linux modules are loaded automatically, but
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| 200 | sometimes it needs some specific direction. The program that loads
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| 201 | modules, <command>modprobe</command> or <command>insmod</command>, uses
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| 202 | <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
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| 203 | needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
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| 204 | uhci_hcd) have been built as modules, they will be loaded in the correct
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| 205 | order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
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| 206 | to avoid a warning being output at boot time.</para>
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[200e466] | 207 |
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[b67f2d6] | 208 | <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
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[200e466] | 209 | the following:</para>
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| 210 |
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[23ba7a00] | 211 | <screen><userinput>install -v -m755 -d /etc/modprobe.d
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[b67f2d6] | 212 | cat > /etc/modprobe.d/usb.conf << "EOF"
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| 213 | <literal># Begin /etc/modprobe.d/usb.conf
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[200e466] | 214 |
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| 215 | install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
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| 216 | install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
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| 217 |
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[b67f2d6] | 218 | # End /etc/modprobe.d/usb.conf</literal>
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[200e466] | 219 | EOF</userinput></screen>
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| 220 |
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| 221 | </sect2>
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| 222 |
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[b78c747] | 223 | <sect2 id="contents-kernel" role="content">
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| 224 | <title>Contents of Linux</title>
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| 225 |
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| 226 | <segmentedlist>
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| 227 | <segtitle>Installed files</segtitle>
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[fe05b08] | 228 | <segtitle>Installed directories</segtitle>
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[b78c747] | 229 |
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| 230 | <seglistitem>
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[2ca8941] | 231 | <seg>config-&linux-version;,
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[c19d13c] | 232 | vmlinux-&linux-version;-lfs-&version;-&linux-version;, and
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[b78c747] | 233 | System.map-&linux-version;</seg>
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[fe05b08] | 234 | <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
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[b78c747] | 235 | </seglistitem>
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| 236 | </segmentedlist>
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| 237 |
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| 238 | <variablelist>
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| 239 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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| 240 | <?dbfo list-presentation="list"?>
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| 241 | <?dbhtml list-presentation="table"?>
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| 242 |
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| 243 | <varlistentry id="config">
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| 244 | <term><filename>config-&linux-version;</filename></term>
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| 245 | <listitem>
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| 246 | <para>Contains all the configuration selections for the kernel</para>
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| 247 | <indexterm zone="ch-bootable-kernel config">
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| 248 | <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
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| 249 | </indexterm>
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| 250 | </listitem>
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| 251 | </varlistentry>
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| 252 |
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| 253 | <varlistentry id="lfskernel">
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[f86263c] | 254 | <term><filename>vmlinux-&linux-version;-lfs-&version;</filename></term>
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[b78c747] | 255 | <listitem>
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| 256 | <para>The engine of the Linux system. When turning on the computer,
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| 257 | the kernel is the first part of the operating system that gets loaded.
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| 258 | It detects and initializes all components of the computer's hardware,
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| 259 | then makes these components available as a tree of files to the
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| 260 | software and turns a single CPU into a multitasking machine capable
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| 261 | of running scores of programs seemingly at the same time</para>
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| 262 | <indexterm zone="ch-bootable-kernel lfskernel">
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| 263 | <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
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| 264 | </indexterm>
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| 265 | </listitem>
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| 266 | </varlistentry>
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| 267 |
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| 268 | <varlistentry id="System.map">
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| 269 | <term><filename>System.map-&linux-version;</filename></term>
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| 270 | <listitem>
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| 271 | <para>A list of addresses and symbols; it maps the entry points and
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| 272 | addresses of all the functions and data structures in the
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| 273 | kernel</para>
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| 274 | <indexterm zone="ch-bootable-kernel System.map">
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| 275 | <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
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| 276 | </indexterm>
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| 277 | </listitem>
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| 278 | </varlistentry>
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| 279 |
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| 280 | </variablelist>
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| 281 |
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| 282 | </sect2>
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[673b0d8] | 283 |
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[6370fa6] | 284 | </sect1>
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