[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[b78c747] | 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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[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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[0ebe9fa4] | 58 | <screen role="nodump"><userinput>make menuconfig</userinput></screen>
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[2081905] | 59 |
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[b78c747] | 60 | <para>Alternatively, <command>make oldconfig</command> may be more
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| 61 | appropriate in some situations. See the <filename>README</filename>
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| 62 | file for more information.</para>
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| 63 |
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| 64 | <para>If desired, skip kernel configuration by copying the kernel
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| 65 | config file, <filename>.config</filename>, from the host system
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| 66 | (assuming it is available) to the unpacked <filename
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| 67 | class="directory">linux-&linux-version;</filename> directory. However,
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| 68 | we do not recommend this option. It is often better to explore all the
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| 69 | configuration menus and create the kernel configuration from
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| 70 | scratch.</para>
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| 71 |
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| 72 | <para>Compile the kernel image and modules:</para>
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[2081905] | 73 |
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[9dfc02f] | 74 | <screen><userinput>make</userinput></screen>
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[2081905] | 75 |
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[d2c332bc] | 76 | <para>If using kernel modules, an <filename>/etc/modprobe.conf</filename>
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| 77 | file may be needed. Information pertaining to modules and kernel
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| 78 | configuration is located in <xref linkend="ch-scripts-udev"/> and in the
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| 79 | kernel documentation in the <filename
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[b78c747] | 80 | class="directory">linux-&linux-version;/Documentation</filename> directory.
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| 81 | Also, <filename>modprobe.conf(5)</filename> may be of interest.</para>
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[4b59d59] | 82 |
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[b78c747] | 83 | <para>Install the modules, if the kernel configuration uses them:</para>
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[2081905] | 84 |
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[9dfc02f] | 85 | <screen><userinput>make modules_install</userinput></screen>
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[2081905] | 86 |
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[b78c747] | 87 | <para>After kernel compilation is complete, additional steps are
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| 88 | required to complete the installation. Some files need to be copied to
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| 89 | the <filename class="directory">/boot</filename> directory.</para>
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[81fd230] | 90 |
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[b78c747] | 91 | <para>The path to the kernel image may vary depending on the platform
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| 92 | being used. The following command assumes an x86 architecture:</para>
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[2081905] | 93 |
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[5998892] | 94 | <screen><userinput>cp -v arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
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[2081905] | 95 |
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[b78c747] | 96 | <para><filename>System.map</filename> is a symbol file for the kernel.
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| 97 | It maps the function entry points of every function in the kernel API,
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| 98 | as well as the addresses of the kernel data structures for the running
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| 99 | kernel. Issue the following command to install the map file:</para>
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[81fd230] | 100 |
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[5998892] | 101 | <screen><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
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[2081905] | 102 |
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[b78c747] | 103 | <para>The kernel configuration file <filename>.config</filename>
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| 104 | produced by the <command>make menuconfig</command> step
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| 105 | above contains all the configuration selections for the kernel
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| 106 | that was just compiled. It is a good idea to keep this file for future
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| 107 | reference:</para>
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[81fd230] | 108 |
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[5998892] | 109 | <screen><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen>
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[2081905] | 110 |
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[a1e18fa] | 111 | <para>Install the documentation for the Linux kernel:</para>
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| 112 |
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[c226182] | 113 | <screen><userinput>install -d /usr/share/doc/linux-&linux-version; &&
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| 114 | cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
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[a1e18fa] | 115 |
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[b78c747] | 116 | <para>It is important to note that the files in the kernel source
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| 117 | directory are not owned by <emphasis>root</emphasis>. Whenever a
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| 118 | package is unpacked as user <emphasis>root</emphasis> (like we did
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| 119 | inside chroot), the files have the user and group IDs of whatever
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| 120 | they were on the packager's computer. This is usually not a problem
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| 121 | for any other package to be installed because the source tree is
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| 122 | removed after the installation. However, the Linux source tree is
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| 123 | often retained for a long time. Because of this, there is a chance
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| 124 | that whatever user ID the packager used will be assigned to somebody
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| 125 | on the machine. That person would then have write access to the kernel
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| 126 | source.</para>
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| 127 |
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| 128 | <para>If the kernel source tree is going to be retained, run
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| 129 | <command>chown -R 0:0</command> on the <filename
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| 130 | class="directory">linux-&linux-version;</filename> directory to ensure
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| 131 | all files are owned by user <emphasis>root</emphasis>.</para>
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| 132 |
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| 133 | <warning>
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| 134 | <para>Some kernel documentation recommends creating a symlink from
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| 135 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
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| 136 | source directory. This is specific to kernels prior to the 2.6 series and
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| 137 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
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| 138 | problems for packages you may wish to build once your base LFS system is
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| 139 | complete.</para>
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| 140 |
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| 141 | <para>Also, the headers in the system's
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| 142 | <filename class="directory">include</filename> directory should
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| 143 | <emphasis>always</emphasis> be the ones against which Glibc was compiled,
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[2cf5d490] | 144 | that is, the sanitised headers from the Linux kernel tarball, and
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| 145 | therefore, should <emphasis>never</emphasis> be replaced by the raw kernel
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| 146 | headers.</para>
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[b78c747] | 147 | </warning>
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| 148 |
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| 149 | </sect2>
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| 150 |
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| 151 | <sect2 id="contents-kernel" role="content">
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| 152 | <title>Contents of Linux</title>
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| 153 |
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| 154 | <segmentedlist>
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| 155 | <segtitle>Installed files</segtitle>
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| 156 |
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| 157 | <seglistitem>
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| 158 | <seg>config-&linux-version;, lfskernel-&linux-version;, and
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| 159 | System.map-&linux-version;</seg>
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| 160 | </seglistitem>
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| 161 | </segmentedlist>
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| 162 |
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| 163 | <variablelist>
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| 164 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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| 165 | <?dbfo list-presentation="list"?>
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| 166 | <?dbhtml list-presentation="table"?>
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| 167 |
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| 168 | <varlistentry id="config">
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| 169 | <term><filename>config-&linux-version;</filename></term>
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| 170 | <listitem>
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| 171 | <para>Contains all the configuration selections for the kernel</para>
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| 172 | <indexterm zone="ch-bootable-kernel config">
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| 173 | <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
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| 174 | </indexterm>
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| 175 | </listitem>
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| 176 | </varlistentry>
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| 177 |
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| 178 | <varlistentry id="lfskernel">
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| 179 | <term><filename>lfskernel-&linux-version;</filename></term>
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| 180 | <listitem>
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| 181 | <para>The engine of the Linux system. When turning on the computer,
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| 182 | the kernel is the first part of the operating system that gets loaded.
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| 183 | It detects and initializes all components of the computer's hardware,
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| 184 | then makes these components available as a tree of files to the
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| 185 | software and turns a single CPU into a multitasking machine capable
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| 186 | of running scores of programs seemingly at the same time</para>
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| 187 | <indexterm zone="ch-bootable-kernel lfskernel">
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| 188 | <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
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| 189 | </indexterm>
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| 190 | </listitem>
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| 191 | </varlistentry>
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| 192 |
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| 193 | <varlistentry id="System.map">
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| 194 | <term><filename>System.map-&linux-version;</filename></term>
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| 195 | <listitem>
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| 196 | <para>A list of addresses and symbols; it maps the entry points and
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| 197 | addresses of all the functions and data structures in the
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| 198 | kernel</para>
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| 199 | <indexterm zone="ch-bootable-kernel System.map">
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| 200 | <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
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| 201 | </indexterm>
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| 202 | </listitem>
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| 203 | </varlistentry>
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| 204 |
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| 205 | </variablelist>
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| 206 |
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| 207 | </sect2>
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[673b0d8] | 208 |
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[6370fa6] | 209 | </sect1>
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