[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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| 11 | <title>Linux-&linux-version;</title>
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| 12 |
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| 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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| 16 |
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| 17 | <sect2 role="package">
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| 18 | <title/>
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| 19 |
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| 20 | <para>The Linux package contains the Linux kernel.</para>
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[673b0d8] | 21 |
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[b78c747] | 22 | <segmentedlist>
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| 23 | <segtitle>&buildtime;</segtitle>
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| 24 | <segtitle>&diskspace;</segtitle>
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[6370fa6] | 25 |
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[b78c747] | 26 | <seglistitem>
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[e4a5635] | 27 | <seg>&linux-ch8-sbu;</seg>
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| 28 | <seg>&linux-ch8-du;</seg>
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[b78c747] | 29 | </seglistitem>
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| 30 | </segmentedlist>
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[a001133] | 31 |
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[b78c747] | 32 | </sect2>
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[2081905] | 33 |
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[b78c747] | 34 | <sect2 role="installation">
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| 35 | <title>Installation of the kernel</title>
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[81fd230] | 36 |
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[b78c747] | 37 | <para>Building the kernel involves a few steps—configuration,
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| 38 | compilation, and installation. Read the <filename>README</filename> file
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| 39 | in the kernel source tree for alternative methods to the way this book
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| 40 | configures the kernel.</para>
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| 41 |
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| 42 | <para>Prepare for compilation by running the following command:</para>
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[b9e738a] | 43 |
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[1d609dce] | 44 | <screen><userinput>make mrproper</userinput></screen>
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[b9e738a] | 45 |
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[b78c747] | 46 | <para>This ensures that the kernel tree is absolutely clean. The
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| 47 | kernel team recommends that this command be issued prior to each
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| 48 | kernel compilation. Do not rely on the source tree being clean after
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| 49 | un-tarring.</para>
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[d72e04a] | 50 |
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[fa21b3d] | 51 | <!-- Support for compiling a keymap into the kernel is deliberately removed -->
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[81fd230] | 52 |
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[b78c747] | 53 | <para>Configure the kernel via a menu-driven interface. BLFS has some
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| 54 | information regarding particular kernel configuration requirements of
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| 55 | packages outside of LFS at <ulink
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| 56 | url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para>
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[2081905] | 57 |
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[2ccccf7] | 58 | <screen role="nodump"><userinput>make LANG=<replaceable><host_LANG_value></replaceable> LC_ALL= menuconfig</userinput></screen>
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| 59 |
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| 60 | <variablelist>
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| 61 | <title>The meaning of the make parameters:</title>
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| 62 |
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| 63 | <varlistentry>
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| 64 | <term><parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term>
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| 65 | <listitem>
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| 66 | <para>This establishes the locale setting to the one used on the host.
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| 67 | This is needed for a proper menuconfig ncurses interface line
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| 68 | drawing on UTF-8 linux text console.</para>
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| 69 |
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| 70 | <para>Be sure to replace <replaceable><host_LANG_value></replaceable>
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| 71 | by the value of the <envar>$LANG</envar> variable from your host.
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[01670aad] | 72 | If not set, you could use instead the host's value of <envar>$LC_ALL</envar>
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[2ccccf7] | 73 | or <envar>$LC_CTYPE</envar>.</para>
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| 74 | </listitem>
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| 75 | </varlistentry>
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| 76 |
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| 77 | </variablelist>
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[2081905] | 78 |
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[b78c747] | 79 | <para>Alternatively, <command>make oldconfig</command> may be more
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| 80 | appropriate in some situations. See the <filename>README</filename>
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| 81 | file for more information.</para>
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| 82 |
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| 83 | <para>If desired, skip kernel configuration by copying the kernel
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| 84 | config file, <filename>.config</filename>, from the host system
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| 85 | (assuming it is available) to the unpacked <filename
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| 86 | class="directory">linux-&linux-version;</filename> directory. However,
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| 87 | we do not recommend this option. It is often better to explore all the
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| 88 | configuration menus and create the kernel configuration from
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| 89 | scratch.</para>
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| 90 |
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| 91 | <para>Compile the kernel image and modules:</para>
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[2081905] | 92 |
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[9dfc02f] | 93 | <screen><userinput>make</userinput></screen>
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[2081905] | 94 |
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[d2c332bc] | 95 | <para>If using kernel modules, an <filename>/etc/modprobe.conf</filename>
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| 96 | file may be needed. Information pertaining to modules and kernel
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| 97 | configuration is located in <xref linkend="ch-scripts-udev"/> and in the
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| 98 | kernel documentation in the <filename
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[b78c747] | 99 | class="directory">linux-&linux-version;/Documentation</filename> directory.
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| 100 | Also, <filename>modprobe.conf(5)</filename> may be of interest.</para>
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[4b59d59] | 101 |
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[b78c747] | 102 | <para>Install the modules, if the kernel configuration uses them:</para>
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[2081905] | 103 |
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[9dfc02f] | 104 | <screen><userinput>make modules_install</userinput></screen>
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[2081905] | 105 |
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[b78c747] | 106 | <para>After kernel compilation is complete, additional steps are
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| 107 | required to complete the installation. Some files need to be copied to
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| 108 | the <filename class="directory">/boot</filename> directory.</para>
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[81fd230] | 109 |
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[b78c747] | 110 | <para>The path to the kernel image may vary depending on the platform
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| 111 | being used. The following command assumes an x86 architecture:</para>
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[2081905] | 112 |
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[5998892] | 113 | <screen><userinput>cp -v arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
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[2081905] | 114 |
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[b78c747] | 115 | <para><filename>System.map</filename> is a symbol file for the kernel.
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| 116 | It maps the function entry points of every function in the kernel API,
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| 117 | as well as the addresses of the kernel data structures for the running
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| 118 | kernel. Issue the following command to install the map file:</para>
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[81fd230] | 119 |
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[5998892] | 120 | <screen><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
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[2081905] | 121 |
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[b78c747] | 122 | <para>The kernel configuration file <filename>.config</filename>
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| 123 | produced by the <command>make menuconfig</command> step
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| 124 | above contains all the configuration selections for the kernel
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| 125 | that was just compiled. It is a good idea to keep this file for future
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| 126 | reference:</para>
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[81fd230] | 127 |
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[5998892] | 128 | <screen><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
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[2081905] | 129 |
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[a1e18fa] | 130 | <para>Install the documentation for the Linux kernel:</para>
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| 131 |
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[71eb6ac] | 132 | <screen><userinput>install -d /usr/share/doc/linux-&linux-version;
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[c226182] | 133 | cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
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[a1e18fa] | 134 |
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[b78c747] | 135 | <para>It is important to note that the files in the kernel source
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| 136 | directory are not owned by <emphasis>root</emphasis>. Whenever a
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| 137 | package is unpacked as user <emphasis>root</emphasis> (like we did
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| 138 | inside chroot), the files have the user and group IDs of whatever
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| 139 | they were on the packager's computer. This is usually not a problem
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| 140 | for any other package to be installed because the source tree is
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| 141 | removed after the installation. However, the Linux source tree is
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| 142 | often retained for a long time. Because of this, there is a chance
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| 143 | that whatever user ID the packager used will be assigned to somebody
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| 144 | on the machine. That person would then have write access to the kernel
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| 145 | source.</para>
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| 146 |
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| 147 | <para>If the kernel source tree is going to be retained, run
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| 148 | <command>chown -R 0:0</command> on the <filename
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| 149 | class="directory">linux-&linux-version;</filename> directory to ensure
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| 150 | all files are owned by user <emphasis>root</emphasis>.</para>
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| 151 |
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| 152 | <warning>
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| 153 | <para>Some kernel documentation recommends creating a symlink from
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| 154 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
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| 155 | source directory. This is specific to kernels prior to the 2.6 series and
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| 156 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
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| 157 | problems for packages you may wish to build once your base LFS system is
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| 158 | complete.</para>
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[6c75ca3] | 159 | </warning>
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[b78c747] | 160 |
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[6c75ca3] | 161 | <warning>
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| 162 | <para>The headers in the system's
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[b78c747] | 163 | <filename class="directory">include</filename> directory should
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| 164 | <emphasis>always</emphasis> be the ones against which Glibc was compiled,
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[2ccccf7] | 165 | that is, the sanitised headers from this Linux kernel tarball.
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[01670aad] | 166 | Therefore, they should <emphasis>never</emphasis> be replaced by either
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[2ccccf7] | 167 | the raw kernel headers or any other kernel sanitized headers.</para>
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[b78c747] | 168 | </warning>
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| 169 |
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| 170 | </sect2>
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| 171 |
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| 172 | <sect2 id="contents-kernel" role="content">
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| 173 | <title>Contents of Linux</title>
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| 174 |
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| 175 | <segmentedlist>
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| 176 | <segtitle>Installed files</segtitle>
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| 177 |
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| 178 | <seglistitem>
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| 179 | <seg>config-&linux-version;, lfskernel-&linux-version;, and
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| 180 | System.map-&linux-version;</seg>
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| 181 | </seglistitem>
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| 182 | </segmentedlist>
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| 183 |
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| 184 | <variablelist>
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| 185 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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| 186 | <?dbfo list-presentation="list"?>
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| 187 | <?dbhtml list-presentation="table"?>
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| 188 |
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| 189 | <varlistentry id="config">
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| 190 | <term><filename>config-&linux-version;</filename></term>
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| 191 | <listitem>
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| 192 | <para>Contains all the configuration selections for the kernel</para>
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| 193 | <indexterm zone="ch-bootable-kernel config">
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| 194 | <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
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| 195 | </indexterm>
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| 196 | </listitem>
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| 197 | </varlistentry>
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| 198 |
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| 199 | <varlistentry id="lfskernel">
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| 200 | <term><filename>lfskernel-&linux-version;</filename></term>
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| 201 | <listitem>
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| 202 | <para>The engine of the Linux system. When turning on the computer,
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| 203 | the kernel is the first part of the operating system that gets loaded.
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| 204 | It detects and initializes all components of the computer's hardware,
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| 205 | then makes these components available as a tree of files to the
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| 206 | software and turns a single CPU into a multitasking machine capable
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| 207 | of running scores of programs seemingly at the same time</para>
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| 208 | <indexterm zone="ch-bootable-kernel lfskernel">
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| 209 | <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
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| 210 | </indexterm>
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| 211 | </listitem>
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| 212 | </varlistentry>
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| 213 |
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| 214 | <varlistentry id="System.map">
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| 215 | <term><filename>System.map-&linux-version;</filename></term>
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| 216 | <listitem>
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| 217 | <para>A list of addresses and symbols; it maps the entry points and
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| 218 | addresses of all the functions and data structures in the
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| 219 | kernel</para>
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| 220 | <indexterm zone="ch-bootable-kernel System.map">
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| 221 | <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
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| 222 | </indexterm>
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| 223 | </listitem>
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| 224 | </varlistentry>
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| 225 |
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| 226 | </variablelist>
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| 227 |
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| 228 | </sect2>
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[673b0d8] | 229 |
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[6370fa6] | 230 | </sect1>
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