[a9e389d] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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[bd48e48] | 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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[a9e389d] | 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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| 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"><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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| 25 | <para os="a">Building the kernel involves a few steps—configuration, |
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| 26 | compilation, and installation. Read the <filename>README</filename> |
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| 27 | file in the kernel source tree for alternative methods to the way this |
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| 28 | book configures the kernel.</para> |
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| 29 | |
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| 30 | <para os="b">Prepare for compilation by running the following command:</para> |
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| 31 | |
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| 32 | <screen os="c"><userinput>make mrproper</userinput></screen> |
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| 33 | |
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| 34 | <para os="d">This ensures that the kernel tree is absolutely clean. The |
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| 35 | kernel team recommends that this command be issued prior to each |
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| 36 | kernel compilation. Do not rely on the source tree being clean after |
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| 37 | un-tarring.</para> |
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| 38 | |
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[f23b5ee] | 39 | <para os="e">Configure the kernel via a menu-driven interface. |
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[a9e389d] | 40 | Please note that the udev bootscript requires "rtc" and "tmpfs" to be |
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| 41 | enabled and built into the kernel, not as modules. BLFS has |
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| 42 | some information regarding particular kernel configuration requirements of |
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| 43 | packages outside of CLFS at <ulink |
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| 44 | url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>:</para> |
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[3ca2208] | 45 | |
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[81d9bce] | 46 | <note os="f"><para>Since we are building for an embedded system we need to make sure |
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[89cc05c] | 47 | our key components are built into the kernel and not as modules. Our key |
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[81d9bce] | 48 | components are console/video, disk, and network. With out these built in our |
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[89cc05c] | 49 | system will not function properly. If your concerned about disk space, your kernel |
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| 50 | should be without modules.</para></note> |
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[a9e389d] | 51 | |
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[6a3c6dc] | 52 | <screen os="g"><userinput>make ARCH=${CLFS_ARCH} CROSS_COMPILE=${CLFS_TARGET}- menuconfig</userinput></screen> |
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[a9e389d] | 53 | |
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[81d9bce] | 54 | <para os="h">Alternatively, <command>make oldconfig</command> may be more |
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[a9e389d] | 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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[81d9bce] | 58 | <para os="i">If desired, skip kernel configuration by copying the kernel |
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[a9e389d] | 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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[81d9bce] | 65 | <para os="j">Compile the kernel image and modules:</para> |
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[a9e389d] | 66 | |
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[6a3c6dc] | 67 | <screen os="k"><userinput>make ARCH=${CLFS_ARCH} CROSS_COMPILE=${CLFS_TARGET}-</userinput></screen> |
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[a9e389d] | 68 | |
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[81d9bce] | 69 | <para os="l">If using kernel modules, an |
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[a9e389d] | 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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[81d9bce] | 77 | <para os="m">Be very careful when reading other documentation relating to |
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[a9e389d] | 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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[81d9bce] | 86 | <screen os="n"><literal>alias char-major-XXX some-module</literal></screen> |
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[a9e389d] | 87 | |
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[81d9bce] | 88 | <para os="o">Because of the complications with Udev and modules, |
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[a9e389d] | 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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[81d9bce] | 92 | <para os="p">Install the modules, if the kernel configuration uses |
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[a9e389d] | 93 | them:</para> |
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| 94 | |
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[6a3c6dc] | 95 | <screen os="q"><userinput>make ARCH=${CLFS_ARCH} CROSS_COMPILE=${CLFS_TARGET}- \ |
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[a9e389d] | 96 | INSTALL_MOD_PATH=${CLFS} modules_install</userinput></screen> |
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| 97 | |
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[81d9bce] | 98 | <para os="r">After kernel compilation is complete, additional steps are |
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[a9e389d] | 99 | required to complete the installation. Some files need to be copied to |
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| 100 | the <filename class="directory">${CLFS}/boot</filename> directory.</para> |
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| 101 | |
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[81d9bce] | 102 | <para os="s">Issue the following command to install the kernel:</para> |
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[a9e389d] | 103 | |
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[81d9bce] | 104 | <screen os="t"><userinput>cp vmlinux ${CLFS}/boot/clfskernel-&linux-version;</userinput></screen> |
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[a9e389d] | 105 | |
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[81d9bce] | 106 | <para os="u"><filename>System.map</filename> is a symbol file for the kernel. |
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[a9e389d] | 107 | It maps the function entry points of every function in the kernel API, |
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| 108 | as well as the addresses of the kernel data structures for the running |
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| 109 | kernel. Issue the following command to install the map file:</para> |
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| 110 | |
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[81d9bce] | 111 | <screen os="v"><userinput>cp System.map ${CLFS}/boot/System.map-&linux-version;</userinput></screen> |
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[f23b5ee] | 112 | |
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[3ca2208] | 113 | <para os="w">If we compiled our kernel with modules and we made sure |
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| 114 | <command>depmod.pl</command> is avaiable from BusyBox, we need to create the |
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| 115 | module dependency list by issuing the following command:</para> |
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[f23b5ee] | 116 | |
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[3ca2208] | 117 | <screen os="x"><userinput>${CLFS}/cross-tools/bin/depmod.pl -F ${CLFS}/boot/System.map \ |
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| 118 | -b ${CLFS}/lib/modules/&linux-version;</userinput></screen> |
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[a9e389d] | 119 | |
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[81d9bce] | 120 | <para os="y">The kernel configuration file <filename>.config</filename> |
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[a9e389d] | 121 | produced by the <command>make menuconfig</command> step above contains |
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| 122 | all the configuration selections for the kernel that was just compiled. |
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| 123 | It is a good idea to keep this file for future reference:</para> |
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| 124 | |
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[81d9bce] | 125 | <screen os="z"><userinput>cp .config ${CLFS}/boot/config-&linux-version;</userinput></screen> |
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[a9e389d] | 126 | |
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[81d9bce] | 127 | <warning os="aa"> |
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[a9e389d] | 128 | <para>Some kernel documentation recommends creating a symlink from |
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| 129 | <filename class="symlink">/usr/src/linux</filename> pointing to the |
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| 130 | kernel source directory. This is specific to kernels prior to the |
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| 131 | 2.6 series and <emphasis>must not</emphasis> be created on an CLFS |
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| 132 | system as it can cause problems for packages you may wish to build |
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| 133 | once your base CLFS system is complete.</para> |
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| 134 | |
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| 135 | </warning> |
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| 136 | |
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[81d9bce] | 137 | <para os="ab">The bootloaders section contains more information on |
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| 138 | how to configure the kernel for specifc bootloaders. Please refer |
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| 139 | to this section for your specific needs.</para> |
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| 140 | |
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[a9e389d] | 141 | </sect2> |
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| 142 | |
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| 143 | <sect2 id="contents-kernel" role="content"> |
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| 144 | <title>Contents of Linux</title> |
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| 145 | |
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| 146 | <segmentedlist> |
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| 147 | <segtitle>Installed files</segtitle> |
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| 148 | |
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| 149 | <seglistitem> |
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| 150 | <seg>config-[linux-version], clfskernel-[linux-version], |
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| 151 | and System.map-[linux-version]</seg> |
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| 152 | </seglistitem> |
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| 153 | </segmentedlist> |
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| 154 | |
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| 155 | <variablelist> |
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| 156 | <bridgehead renderas="sect3">Short Descriptions</bridgehead> |
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| 157 | <?dbfo list-presentation="list"?> |
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| 158 | <?dbhtml list-presentation="table"?> |
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| 159 | |
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| 160 | <varlistentry id="config"> |
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| 161 | <term><filename>config-[linux-version]</filename></term> |
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| 162 | <listitem> |
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| 163 | <para>Contains all the configuration selections for the kernel</para> |
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| 164 | <indexterm zone="ch-bootable-kernel config"> |
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| 165 | <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary> |
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| 166 | </indexterm> |
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| 167 | </listitem> |
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| 168 | </varlistentry> |
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| 169 | |
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| 170 | <varlistentry id="clfskernel"> |
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| 171 | <term><filename>clfskernel-[linux-version]</filename></term> |
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| 172 | <listitem> |
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| 173 | <para>The engine of the Linux system. When turning on the |
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| 174 | computer, the kernel is the first part of the operating system |
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| 175 | that gets loaded. It detects and initializes all components of |
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| 176 | the computer's hardware, then makes these components available |
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| 177 | as a tree of files to the software and turns a single CPU into |
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| 178 | a multitasking machine capable of running scores of programs |
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| 179 | seemingly at the same time.</para> |
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| 180 | <indexterm zone="ch-bootable-kernel clfskernel"> |
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| 181 | <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary> |
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| 182 | </indexterm> |
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| 183 | </listitem> |
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| 184 | </varlistentry> |
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| 185 | |
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| 186 | <varlistentry id="System.map"> |
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| 187 | <term><filename>System.map-[linux-version]</filename></term> |
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| 188 | <listitem> |
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| 189 | <para>A list of addresses and symbols; it maps the entry points |
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| 190 | and addresses of all the functions and data structures in the |
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| 191 | kernel</para> |
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| 192 | <indexterm zone="ch-bootable-kernel System.map"> |
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| 193 | <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary> |
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| 194 | </indexterm> |
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| 195 | </listitem> |
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| 196 | </varlistentry> |
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| 197 | |
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| 198 | </variablelist> |
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| 199 | |
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| 200 | </sect2> |
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| 201 | |
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| 202 | </sect1> |
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