[3f8be484] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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[aa18ac0] | 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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[3f8be484] | 4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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| 5 | %general-entities; |
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| 6 | ]> |
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| 7 | |
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| 8 | <sect1 id="ch-bootable-kernel" role="wrap"> |
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| 9 | <?dbhtml filename="kernel.html"?> |
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| 10 | |
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[43daa01] | 11 | <title>Linux-&linux-version;</title> |
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[3f8be484] | 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"><title/> |
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| 18 | <para>The Linux package contains the Linux kernel.</para> |
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| 19 | |
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| 20 | </sect2> |
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| 21 | |
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| 22 | <sect2 role="installation"> |
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| 23 | <title>Installation of the kernel</title> |
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| 24 | |
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[4a7ae16] | 25 | <para os="a1">A number of vulnerabilities have come to light after the |
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| 26 | stable kernel team stopped supporting 2.6.24. The following patch addresses |
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| 27 | them:</para> |
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| 28 | |
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| 29 | <screen os="a2"><userinput>patch -Np1 -i ../&linux-security-patch;</userinput></screen> |
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| 30 | |
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[3f8be484] | 31 | <para os="a">Building the kernel involves a few steps—configuration, |
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| 32 | compilation, and installation. Read the <filename>README</filename> |
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| 33 | file in the kernel source tree for alternative methods to the way this |
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| 34 | book configures the kernel.</para> |
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| 35 | |
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| 36 | <para os="b">Prepare for compilation by running the following command:</para> |
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| 37 | |
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| 38 | <screen os="c"><userinput>make mrproper</userinput></screen> |
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| 39 | |
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| 40 | <para os="d">This ensures that the kernel tree is absolutely clean. The |
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| 41 | kernel team recommends that this command be issued prior to each |
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| 42 | kernel compilation. Do not rely on the source tree being clean after |
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| 43 | un-tarring.</para> |
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| 44 | |
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[77e81f1] | 45 | <para os="h">Configure the kernel via a menu-driven interface. |
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| 46 | Please note that the udev bootscript requires "rtc" and "tmpfs" to be |
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[0d4607d] | 47 | enabled and built into the kernel, not as modules. CBLFS has |
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[3f8be484] | 48 | some information regarding particular kernel configuration requirements of |
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[fb40919] | 49 | packages outside of CLFS at <ulink |
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[0d4607d] | 50 | url="&cblfs-root;"/>:</para> |
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[3f8be484] | 51 | |
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| 52 | <screen os="i"><userinput>make menuconfig</userinput></screen> |
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| 53 | |
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| 54 | <para os="j">Alternatively, <command>make oldconfig</command> may be more |
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| 55 | appropriate in some situations. See the <filename>README</filename> |
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| 56 | file for more information.</para> |
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| 57 | |
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| 58 | <para os="k">If desired, skip kernel configuration by copying the kernel |
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| 59 | config file, <filename>.config</filename>, from the host system |
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| 60 | (assuming it is available) to the root directory of the unpacked kernel |
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| 61 | sources. However, we do not recommend this option. It is often better |
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| 62 | to explore all the configuration menus and create the kernel configuration |
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| 63 | from scratch.</para> |
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| 64 | |
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| 65 | <para os="m">Compile the kernel image and modules:</para> |
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| 66 | |
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| 67 | <screen os="n"><userinput>make</userinput></screen> |
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| 68 | |
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| 69 | <para os="o">If using kernel modules, an |
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| 70 | <filename>/etc/modprobe.conf</filename> file may be needed. |
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| 71 | Information pertaining to modules and kernel configuration is |
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| 72 | located in the kernel documentation in the <filename |
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| 73 | class="directory">Documentation</filename> directory of the kernel |
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| 74 | sources tree. Also, <filename>modprobe.conf(5)</filename> may |
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| 75 | be of interest.</para> |
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| 76 | |
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| 77 | <para os="p">Be very careful when reading other documentation relating to |
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| 78 | kernel modules because it usually applies to 2.4.x kernels only. As |
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| 79 | far as we know, kernel configuration issues specific to Hotplug and |
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| 80 | Udev are not documented. The problem is that Udev will create a device |
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| 81 | node only if Hotplug or a user-written script inserts the corresponding |
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| 82 | module into the kernel, and not all modules are detectable by Hotplug. |
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| 83 | Note that statements like the one below in the |
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| 84 | <filename>/etc/modprobe.conf</filename> file do not work with Udev:</para> |
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| 85 | |
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| 86 | <screen os="q"><literal>alias char-major-XXX some-module</literal></screen> |
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| 87 | |
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[5d9d2e5] | 88 | <para os="r">Because of the complications with Udev and modules, |
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[3f8be484] | 89 | we strongly recommend starting with a completely non-modular kernel |
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| 90 | configuration, especially if this is the first time using Udev.</para> |
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| 91 | |
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| 92 | <para os="s">Install the modules, if the kernel configuration uses |
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| 93 | them:</para> |
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| 94 | |
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| 95 | <screen os="t"><userinput>make modules_install</userinput></screen> |
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| 96 | |
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| 97 | <para os="u">After kernel compilation is complete, additional steps are |
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| 98 | required to complete the installation. Some files need to be copied to |
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| 99 | the <filename class="directory">/boot</filename> directory.</para> |
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| 100 | |
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| 101 | <para os="v">Issue the following command to install the kernel:</para> |
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| 102 | |
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[e51ba26] | 103 | <screen><userinput>cp -v arch/i386/boot/bzImage /boot/clfskernel-&linux-version;</userinput></screen> |
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[3f8be484] | 104 | |
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| 105 | <para os="w"><filename>System.map</filename> is a symbol file for the kernel. |
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| 106 | It maps the function entry points of every function in the kernel API, |
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| 107 | as well as the addresses of the kernel data structures for the running |
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| 108 | kernel. Issue the following command to install the map file:</para> |
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| 109 | |
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[e51ba26] | 110 | <screen os="w1"><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen> |
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[3f8be484] | 111 | |
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| 112 | <para os="x">The kernel configuration file <filename>.config</filename> |
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| 113 | produced by the <command>make menuconfig</command> step above contains |
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| 114 | all the configuration selections for the kernel that was just compiled. |
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| 115 | It is a good idea to keep this file for future reference:</para> |
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| 116 | |
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[e51ba26] | 117 | <screen os="x1"><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen> |
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[3f8be484] | 118 | |
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| 119 | <para os="y">It is important to note that the files in the kernel source |
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| 120 | directory are not owned by <systemitem class="username">root</systemitem>. |
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| 121 | Whenever a package is unpacked as user <systemitem |
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[a7fa075] | 122 | class="username">root</systemitem> (like we do inside the final-system |
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| 123 | build environment), the files have the user and group IDs of whatever |
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[3f8be484] | 124 | they were on the packager's computer. This is usually not a problem |
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| 125 | for any other package to be installed because the source tree is |
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| 126 | removed after the installation. However, the Linux source tree is |
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[a7fa075] | 127 | often retained for a long time. Because of this, there is a chance |
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[3f8be484] | 128 | that whatever user ID the packager used will be assigned to somebody |
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| 129 | on the machine. That person would then have write access to the kernel |
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| 130 | source.</para> |
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| 131 | |
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[43daa01] | 132 | <para os="y1">If the kernel source tree is going to retained, run |
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[3f8be484] | 133 | <command>chown -R 0:0</command> on the <filename |
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[43daa01] | 134 | class="directory">linux-&linux-version;</filename> directory to |
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[3f8be484] | 135 | ensure all files are owned by user <systemitem |
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| 136 | class="username">root</systemitem>.</para> |
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| 137 | |
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| 138 | <warning os="z"> |
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| 139 | <para>Some kernel documentation recommends creating a symlink from |
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| 140 | <filename class="symlink">/usr/src/linux</filename> pointing to the |
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| 141 | kernel source directory. This is specific to kernels prior to the |
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[fb40919] | 142 | 2.6 series and <emphasis>must not</emphasis> be created on a CLFS |
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[3f8be484] | 143 | system as it can cause problems for packages you may wish to build |
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[fb40919] | 144 | once your base CLFS system is complete.</para> |
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[3f8be484] | 145 | |
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| 146 | <para>Also, the headers in the system's <filename |
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| 147 | class="directory">include</filename> directory should |
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| 148 | <emphasis>always</emphasis> be the ones against which Glibc was |
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[5d9d2e5] | 149 | compiled (from the Linux-Headers package) and should |
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| 150 | <emphasis>never</emphasis> be replaced by the kernel headers.</para> |
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[3f8be484] | 151 | </warning> |
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| 152 | |
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| 153 | </sect2> |
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| 154 | |
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| 155 | <sect2 id="contents-kernel" role="content"> |
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| 156 | <title>Contents of Linux</title> |
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| 157 | |
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| 158 | <segmentedlist> |
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| 159 | <segtitle>Installed files</segtitle> |
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| 160 | |
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| 161 | <seglistitem> |
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[3f76cac] | 162 | <seg>config-[linux-version], clfskernel-[linux-version], |
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[3f8be484] | 163 | and System.map-[linux-version]</seg> |
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| 164 | </seglistitem> |
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| 165 | </segmentedlist> |
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| 166 | |
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| 167 | <variablelist> |
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| 168 | <bridgehead renderas="sect3">Short Descriptions</bridgehead> |
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| 169 | <?dbfo list-presentation="list"?> |
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| 170 | <?dbhtml list-presentation="table"?> |
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| 171 | |
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| 172 | <varlistentry id="config"> |
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| 173 | <term><filename>config-[linux-version]</filename></term> |
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| 174 | <listitem> |
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| 175 | <para>Contains all the configuration selections for the kernel</para> |
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| 176 | <indexterm zone="ch-bootable-kernel config"> |
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| 177 | <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary> |
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| 178 | </indexterm> |
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| 179 | </listitem> |
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| 180 | </varlistentry> |
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| 181 | |
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[3f76cac] | 182 | <varlistentry id="clfskernel"> |
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| 183 | <term><filename>clfskernel-[linux-version]</filename></term> |
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[3f8be484] | 184 | <listitem> |
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| 185 | <para>The engine of the Linux system. When turning on the |
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| 186 | computer, the kernel is the first part of the operating system |
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| 187 | that gets loaded. It detects and initializes all components of |
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| 188 | the computer's hardware, then makes these components available |
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| 189 | as a tree of files to the software and turns a single CPU into |
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| 190 | a multitasking machine capable of running scores of programs |
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| 191 | seemingly at the same time.</para> |
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[3f76cac] | 192 | <indexterm zone="ch-bootable-kernel clfskernel"> |
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| 193 | <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary> |
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[3f8be484] | 194 | </indexterm> |
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| 195 | </listitem> |
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| 196 | </varlistentry> |
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| 197 | |
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| 198 | <varlistentry id="System.map"> |
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| 199 | <term><filename>System.map-[linux-version]</filename></term> |
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| 200 | <listitem> |
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| 201 | <para>A list of addresses and symbols; it maps the entry points |
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| 202 | and addresses of all the functions and data structures in the |
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| 203 | kernel</para> |
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| 204 | <indexterm zone="ch-bootable-kernel System.map"> |
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| 205 | <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary> |
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| 206 | </indexterm> |
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| 207 | </listitem> |
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| 208 | </varlistentry> |
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| 209 | |
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| 210 | </variablelist> |
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| 211 | |
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| 212 | </sect2> |
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| 213 | |
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| 214 | </sect1> |
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