1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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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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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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39 | <para os="e">Configure the kernel via a menu-driven interface. |
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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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45 | |
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46 | <note os="f"><para>Since we are building for an embedded system we need to make sure |
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47 | our key components are built into the kernel and not as modules. Our key |
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48 | components are console/video, disk, and network. With out these built in our |
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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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51 | |
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52 | <screen os="g"><userinput>make ARCH=i386 CROSS_COMPILE=${CLFS_TARGET}- menuconfig</userinput></screen> |
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53 | |
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54 | <para os="h">Alternatively, <command>make oldconfig</command> may be more |
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55 | appropriate in some situations. See the <filename>README</filename> |
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56 | file for more information.</para> |
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57 | |
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58 | <para os="i">If desired, skip kernel configuration by copying the kernel |
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59 | config file, <filename>.config</filename>, from the host system |
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60 | (assuming it is available) to the root directory of the unpacked kernel |
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61 | sources. However, we do not recommend this option. It is often better |
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62 | to explore all the configuration menus and create the kernel configuration |
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63 | from scratch.</para> |
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64 | |
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65 | <para os="j">Compile the kernel image and modules:</para> |
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66 | |
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67 | <screen os="k"><userinput>make ARCH=i386 CROSS_COMPILE=${CLFS_TARGET}-</userinput></screen> |
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68 | |
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69 | <para os="l">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="m">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="n"><literal>alias char-major-XXX some-module</literal></screen> |
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87 | |
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88 | <para os="o">Because of the complications with Udev and modules, |
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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="p">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="q"><userinput>make ARCH=i386 CROSS_COMPILE=${CLFS_TARGET}- \ |
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96 | INSTALL_MOD_PATH=${CLFS} modules_install</userinput></screen> |
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97 | |
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98 | <para os="r">After kernel compilation is complete, additional steps are |
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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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102 | <para os="s">Issue the following command to install the kernel:</para> |
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103 | |
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104 | <screen os="t"><userinput>cp vmlinux ${CLFS}/boot/clfskernel-&linux-version;</userinput></screen> |
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105 | |
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106 | <para os="u"><filename>System.map</filename> is a symbol file for the kernel. |
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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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111 | <screen os="v"><userinput>cp System.map ${CLFS}/boot/System.map-&linux-version;</userinput></screen> |
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112 | |
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113 | <para os="w">If we compiled our kernel with modules and we made sure depmod.pl |
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114 | is avaiable from busybox, we need to create the module dependency list by |
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115 | issuing the following command:</para> |
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116 | |
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117 | <screen os="x"><userinput>${CLFS}/cross-tools/bin/depmod.pl -F ${CLFS}/boot/System.map -b ${CLFS}/lib/modules/&linux-version;</userinput></screen> |
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118 | |
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119 | <para os="y">The kernel configuration file <filename>.config</filename> |
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120 | produced by the <command>make menuconfig</command> step above contains |
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121 | all the configuration selections for the kernel that was just compiled. |
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122 | It is a good idea to keep this file for future reference:</para> |
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123 | |
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124 | <screen os="z"><userinput>cp .config ${CLFS}/boot/config-&linux-version;</userinput></screen> |
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125 | |
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126 | <warning os="aa"> |
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127 | <para>Some kernel documentation recommends creating a symlink from |
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128 | <filename class="symlink">/usr/src/linux</filename> pointing to the |
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129 | kernel source directory. This is specific to kernels prior to the |
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130 | 2.6 series and <emphasis>must not</emphasis> be created on an CLFS |
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131 | system as it can cause problems for packages you may wish to build |
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132 | once your base CLFS system is complete.</para> |
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133 | |
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134 | <para>Also, the headers in the system's <filename |
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135 | class="directory">include</filename> directory should |
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136 | <emphasis>always</emphasis> be the ones against which Glibc was |
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137 | compiled (from the Linux-Headers package) and should |
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138 | <emphasis>never</emphasis> be replaced by the kernel headers.</para> |
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139 | </warning> |
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140 | |
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141 | <para os="ab">The bootloaders section contains more information on |
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142 | how to configure the kernel for specifc bootloaders. Please refer |
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143 | to this section for your specific needs.</para> |
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144 | |
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145 | </sect2> |
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146 | |
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147 | <sect2 id="contents-kernel" role="content"> |
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148 | <title>Contents of Linux</title> |
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149 | |
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150 | <segmentedlist> |
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151 | <segtitle>Installed files</segtitle> |
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152 | |
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153 | <seglistitem> |
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154 | <seg>config-[linux-version], clfskernel-[linux-version], |
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155 | and System.map-[linux-version]</seg> |
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156 | </seglistitem> |
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157 | </segmentedlist> |
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158 | |
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159 | <variablelist> |
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160 | <bridgehead renderas="sect3">Short Descriptions</bridgehead> |
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161 | <?dbfo list-presentation="list"?> |
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162 | <?dbhtml list-presentation="table"?> |
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163 | |
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164 | <varlistentry id="config"> |
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165 | <term><filename>config-[linux-version]</filename></term> |
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166 | <listitem> |
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167 | <para>Contains all the configuration selections for the kernel</para> |
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168 | <indexterm zone="ch-bootable-kernel config"> |
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169 | <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary> |
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170 | </indexterm> |
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171 | </listitem> |
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172 | </varlistentry> |
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173 | |
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174 | <varlistentry id="clfskernel"> |
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175 | <term><filename>clfskernel-[linux-version]</filename></term> |
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176 | <listitem> |
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177 | <para>The engine of the Linux system. When turning on the |
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178 | computer, the kernel is the first part of the operating system |
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179 | that gets loaded. It detects and initializes all components of |
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180 | the computer's hardware, then makes these components available |
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181 | as a tree of files to the software and turns a single CPU into |
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182 | a multitasking machine capable of running scores of programs |
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183 | seemingly at the same time.</para> |
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184 | <indexterm zone="ch-bootable-kernel clfskernel"> |
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185 | <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary> |
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186 | </indexterm> |
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187 | </listitem> |
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188 | </varlistentry> |
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189 | |
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190 | <varlistentry id="System.map"> |
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191 | <term><filename>System.map-[linux-version]</filename></term> |
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192 | <listitem> |
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193 | <para>A list of addresses and symbols; it maps the entry points |
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194 | and addresses of all the functions and data structures in the |
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195 | kernel</para> |
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196 | <indexterm zone="ch-bootable-kernel System.map"> |
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197 | <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary> |
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198 | </indexterm> |
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199 | </listitem> |
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200 | </varlistentry> |
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201 | |
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202 | </variablelist> |
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203 | |
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204 | </sect2> |
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205 | |
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206 | </sect1> |
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