[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[46a2e9c] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.4/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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[46a2e9c] | 7 |
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[81fd230] | 8 | <sect1 id="ch-bootable-kernel" role="wrap">
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[46a2e9c] | 9 | <?dbhtml filename="kernel.html"?>
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[673b0d8] | 10 |
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[46a2e9c] | 11 | <title>Linux-&linux-version;</title>
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[6370fa6] | 12 |
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[46a2e9c] | 13 | <indexterm zone="ch-bootable-kernel">
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| 14 | <primary sortas="a-Linux">Linux</primary>
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| 15 | </indexterm>
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[5888299] | 16 |
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[46a2e9c] | 17 | <sect2 role="package">
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| 18 | <title/>
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[a001133] | 19 |
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[46a2e9c] | 20 | <para>The Linux package contains the Linux kernel.</para>
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[a001133] | 21 |
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[46a2e9c] | 22 | <segmentedlist>
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| 23 | <segtitle>&buildtime;</segtitle>
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| 24 | <segtitle>&diskspace;</segtitle>
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[2081905] | 25 |
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[46a2e9c] | 26 | <seglistitem>
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| 27 | <seg>4.20 SBU</seg>
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| 28 | <seg>181 MB</seg>
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| 29 | </seglistitem>
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| 30 | </segmentedlist>
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[81fd230] | 31 |
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[46a2e9c] | 32 | <segmentedlist>
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| 33 | <segtitle>&dependencies;</segtitle>
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[b9e738a] | 34 |
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[46a2e9c] | 35 | <seglistitem>
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| 36 | <seg>Bash, Binutils, Coreutils, Findutils, GCC, Glibc, Grep, Gzip,
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| 37 | Make, Modutils, Perl, and Sed</seg>
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| 38 | </seglistitem>
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| 39 | </segmentedlist>
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[b9e738a] | 40 |
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[46a2e9c] | 41 | </sect2>
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[d72e04a] | 42 |
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[46a2e9c] | 43 | <sect2 role="installation">
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| 44 | <title>Installation of the kernel</title>
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[89d204ea] | 45 |
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[46a2e9c] | 46 | <para>Building the kernel involves a few steps—configuration,
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| 47 | compilation, and installation. Read the <filename>README</filename> file
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| 48 | in the kernel source tree for alternative methods to the way this book
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| 49 | configures the kernel.</para>
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[89d204ea] | 50 |
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[46a2e9c] | 51 | <para>By default, the Linux kernel generates wrong sequences of bytes when
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| 52 | dead keys are used in UTF-8 keyboard mode. Also, one cannot copy and paste
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| 53 | non-ASCII characters when UTF-8 mode is active. Fix these issues with the
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| 54 | patch:</para>
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[81fd230] | 55 |
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[46a2e9c] | 56 | <screen><userinput>patch -Np1 -i ../&linux-utf8-patch;</userinput></screen>
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[2081905] | 57 |
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[46a2e9c] | 58 | <para>Prepare for compilation by running the following command:</para>
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[2081905] | 59 |
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[46a2e9c] | 60 | <screen><userinput>make mrproper</userinput></screen>
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[81fd230] | 61 |
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[46a2e9c] | 62 | <para>This ensures that the kernel tree is absolutely clean. The
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| 63 | kernel team recommends that this command be issued prior to each
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| 64 | kernel compilation. Do not rely on the source tree being clean after
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| 65 | un-tarring.</para>
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[81fd230] | 66 |
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[46a2e9c] | 67 | <!-- Support for compiling a keymap into the kernel is deliberately removed -->
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| 68 |
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| 69 | <para>Configure the kernel via a menu-driven interface. BLFS has some
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| 70 | information regarding particular kernel configuration requirements of
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| 71 | packages outside of LFS at <ulink
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| 72 | url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para>
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| 73 |
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| 74 | <screen role="nodump"><userinput>make menuconfig</userinput></screen>
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[741921c] | 75 |
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[46a2e9c] | 76 | <para>Alternatively, <command>make oldconfig</command> may be more
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| 77 | appropriate in some situations. See the <filename>README</filename>
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| 78 | file for more information.</para>
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| 79 |
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| 80 | <para>If desired, skip kernel configuration by copying the kernel
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| 81 | config file, <filename>.config</filename>, from the host system
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| 82 | (assuming it is available) to the unpacked <filename
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| 83 | class="directory">linux-&linux-version;</filename> directory. However,
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| 84 | we do not recommend this option. It is often better to explore all the
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| 85 | configuration menus and create the kernel configuration from
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| 86 | scratch.</para>
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| 87 |
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| 88 | <note>
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| 89 | <para>NPTL requires the kernel to be compiled with GCC-3.x or later, in
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| 90 | this case &gcc-version;. It is not recommended to compile the kernel with
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| 91 | GCC-2.95.x, as this causes failures in the Glibc test suite. Normally,
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| 92 | this wouldn't be mentioned as LFS doesn't build GCC-2.95.x. Unfortunately,
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| 93 | the kernel documentation is outdated and still claims GCC-2.95.3 is the
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| 94 | recommended compiler.</para>
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| 95 | </note>
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| 96 |
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| 97 | <para>Compile the kernel image and modules:</para>
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[2081905] | 98 |
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[9dfc02f] | 99 | <screen><userinput>make</userinput></screen>
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[2081905] | 100 |
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[46a2e9c] | 101 | <para>If using kernel modules, an <filename>/etc/modprobe.conf</filename> file
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| 102 | may be needed. Information pertaining to modules and kernel configuration is
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| 103 | located in the kernel documentation in the <filename
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| 104 | class="directory">linux-&linux-version;/Documentation</filename> directory.
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| 105 | Also, <filename>modprobe.conf(5)</filename> may be of interest.</para>
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[4b59d59] | 106 |
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[46a2e9c] | 107 | <para>Be very careful when reading other documentation relating to kernel
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| 108 | modules because it usually applies to 2.4.x kernels only. As far as we know,
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| 109 | kernel configuration issues specific to Hotplug and Udev are not documented.
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| 110 | The problem is that Udev will create a device node only if Hotplug or a
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| 111 | user-written script inserts the corresponding module into the kernel, and not
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| 112 | all modules are detectable by Hotplug. Note that statements like the one below
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| 113 | in the <filename>/etc/modprobe.conf</filename> file do not work with
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| 114 | Udev:</para>
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[81fd230] | 115 |
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[46a2e9c] | 116 | <screen><literal>alias char-major-XXX some-module</literal></screen>
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[81fd230] | 117 |
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[46a2e9c] | 118 | <para>Because of the complications with Hotplug, Udev, and modules, we
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| 119 | strongly recommend starting with a completely non-modular kernel
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| 120 | configuration, especially if this is the first time using Udev.</para>
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[81fd230] | 121 |
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[46a2e9c] | 122 | <para>Install the modules, if the kernel configuration uses them:</para>
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[2081905] | 123 |
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[9dfc02f] | 124 | <screen><userinput>make modules_install</userinput></screen>
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[2081905] | 125 |
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[46a2e9c] | 126 | <para>After kernel compilation is complete, additional steps are
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| 127 | required to complete the installation. Some files need to be copied to
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| 128 | the <filename class="directory">/boot</filename> directory.</para>
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[81fd230] | 129 |
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[46a2e9c] | 130 | <para>The path to the kernel image may vary depending on the platform
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| 131 | being used. The following command assumes an x86 architecture:</para>
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[2081905] | 132 |
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[5998892] | 133 | <screen><userinput>cp -v arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
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[2081905] | 134 |
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[46a2e9c] | 135 | <para><filename>System.map</filename> is a symbol file for the kernel.
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| 136 | It maps the function entry points of every function in the kernel API,
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| 137 | as well as the addresses of the kernel data structures for the running
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| 138 | kernel. Issue the following command to install the map file:</para>
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[81fd230] | 139 |
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[5998892] | 140 | <screen><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
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[2081905] | 141 |
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[46a2e9c] | 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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[5998892] | 148 | <screen><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
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[2081905] | 149 |
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[46a2e9c] | 150 | <para>It is important to note that the files in the kernel source
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| 151 | directory are not owned by <emphasis>root</emphasis>. Whenever a
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| 152 | package is unpacked as user <emphasis>root</emphasis> (like we did
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| 153 | inside chroot), the files have the user and group IDs of whatever
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| 154 | they were on the packager's computer. This is usually not a problem
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| 155 | for any other package to be installed because the source tree is
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| 156 | removed after the installation. However, the Linux source tree is
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| 157 | often retained for a long time. Because of this, there is a chance
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| 158 | that whatever user ID the packager used will be assigned to somebody
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| 159 | on the machine. That person would then have write access to the kernel
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| 160 | source.</para>
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| 161 |
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| 162 | <para>If the kernel source tree is going to be retained, run
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| 163 | <command>chown -R 0:0</command> on the <filename
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| 164 | class="directory">linux-&linux-version;</filename> directory to ensure
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| 165 | all files are owned by user <emphasis>root</emphasis>.</para>
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| 166 |
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| 167 | <warning>
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| 168 | <para>Some kernel documentation recommends creating a symlink from
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| 169 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
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| 170 | source directory. This is specific to kernels prior to the 2.6 series and
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| 171 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
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| 172 | problems for packages you may wish to build once your base LFS system is
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| 173 | complete.</para>
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| 174 |
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| 175 | <para>Also, the headers in the system's
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| 176 | <filename class="directory">include</filename> directory should
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| 177 | <emphasis>always</emphasis> be the ones against which Glibc was compiled,
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| 178 | that is, the ones from the Linux-Libc-Headers package, and therefore, should
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| 179 | <emphasis>never</emphasis> be replaced by the kernel headers.</para>
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| 180 | </warning>
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| 181 |
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| 182 | </sect2>
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| 183 |
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| 184 |
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| 185 | <sect2 id="contents-kernel" role="content">
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| 186 | <title>Contents of Linux</title>
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| 187 |
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| 188 | <segmentedlist>
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| 189 | <segtitle>Installed files</segtitle>
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| 190 |
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| 191 | <seglistitem>
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| 192 | <seg>config-&linux-version;, lfskernel-&linux-version;, and
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| 193 | System.map-&linux-version;</seg>
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| 194 | </seglistitem>
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| 195 | </segmentedlist>
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| 196 |
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| 197 | <variablelist>
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| 198 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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| 199 | <?dbfo list-presentation="list"?>
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| 200 | <?dbhtml list-presentation="table"?>
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| 201 |
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| 202 | <varlistentry id="config">
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| 203 | <term><filename>config-&linux-version;</filename></term>
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| 204 | <listitem>
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| 205 | <para>Contains all the configuration selections for the kernel</para>
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| 206 | <indexterm zone="ch-bootable-kernel config">
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| 207 | <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
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| 208 | </indexterm>
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| 209 | </listitem>
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| 210 | </varlistentry>
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| 211 |
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| 212 | <varlistentry id="lfskernel">
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| 213 | <term><filename>lfskernel-&linux-version;</filename></term>
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| 214 | <listitem>
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| 215 | <para>The engine of the Linux system. When turning on the computer,
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| 216 | the kernel is the first part of the operating system that gets loaded.
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| 217 | It detects and initializes all components of the computer's hardware,
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| 218 | then makes these components available as a tree of files to the
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| 219 | software and turns a single CPU into a multitasking machine capable
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| 220 | of running scores of programs seemingly at the same time</para>
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| 221 | <indexterm zone="ch-bootable-kernel lfskernel">
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| 222 | <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
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| 223 | </indexterm>
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| 224 | </listitem>
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| 225 | </varlistentry>
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| 226 |
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| 227 | <varlistentry id="System.map">
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| 228 | <term><filename>System.map-&linux-version;</filename></term>
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| 229 | <listitem>
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| 230 | <para>A list of addresses and symbols; it maps the entry points and
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| 231 | addresses of all the functions and data structures in the
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| 232 | kernel</para>
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| 233 | <indexterm zone="ch-bootable-kernel System.map">
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| 234 | <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
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| 235 | </indexterm>
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| 236 | </listitem>
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| 237 | </varlistentry>
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| 238 |
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| 239 | </variablelist>
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| 240 |
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| 241 | </sect2>
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[673b0d8] | 242 |
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[6370fa6] | 243 | </sect1>
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