1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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3 | <!ENTITY % general-entities SYSTEM "../general.ent">
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4 | %general-entities;
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5 | ]>
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6 | <sect1 id="ch-bootable-kernel" xreflabel="Linux" role="wrap">
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7 | <title>Linux-&linux-version;</title>
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8 | <?dbhtml filename="kernel.html"?>
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9 |
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10 | <indexterm zone="ch-bootable-kernel"><primary sortas="a-Linux">Linux</primary></indexterm>
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11 |
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12 | <sect2 role="package"><title/>
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13 | <para>The Linux package contains the kernel and the header files.</para>
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14 |
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15 | <segmentedlist>
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16 | <segtitle>&buildtime;</segtitle>
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17 | <segtitle>&diskspace;</segtitle>
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18 | <seglistitem><seg>All default options: 4.20 SBU</seg>
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19 | <seg>All default options: 181 MB</seg></seglistitem>
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20 | </segmentedlist>
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21 |
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22 | <segmentedlist>
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23 | <segtitle>Linux installation depends on</segtitle>
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24 | <seglistitem><seg>Bash, Binutils, Coreutils, Findutils,
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25 | GCC, Glibc, Grep, Gzip, Make, Modutils, Perl, Sed</seg></seglistitem>
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26 | </segmentedlist>
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27 | </sect2>
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28 |
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29 | <sect2 role="installation">
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30 | <title>Installation of the kernel</title>
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31 |
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32 | <para>Building the kernel involves a few steps: configuration, compilation, and
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33 | installation. If you don't like the way this book configures the kernel, view
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34 | the <filename>README</filename> file in the kernel source tree for alternative
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35 | methods.</para>
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36 |
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37 | <para>Prepare for compilation by running the following command:</para>
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38 |
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39 | <screen><userinput>make mrproper</userinput></screen>
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40 |
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41 | <para>This ensures that the kernel tree is absolutely clean. The kernel team
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42 | recommends that this command be issued prior to <emphasis>each</emphasis>
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43 | kernel compilation. You shouldn't rely on the source tree being clean after
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44 | un-tarring.</para>
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45 |
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46 | <para>Configure the kernel via a menu-driven interface:</para>
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47 |
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48 | <screen><userinput>make menuconfig</userinput></screen>
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49 |
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50 | <para><userinput>make oldconfig</userinput> may be more appropriate in some
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51 | situations. See the <filename>README</filename> file for more
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52 | information.</para>
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53 |
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54 | <para>If you wish, you may skip kernel configuration by simply copying the
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55 | kernel config file, <filename>.config</filename>, from your host system
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56 | (assuming it is available) to the unpacked <filename class="directory">linux-&linux-version;</filename>
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57 | directory. However, we
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58 | don't recommend this option. You're much better off exploring all the
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59 | configuration menus and creating your own kernel configuration from
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60 | scratch.</para>
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61 |
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62 | <para>For POSIX shared memory support, ensure that the kernel config option
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63 | <quote>Virtual memory file system support</quote> is enabled. It resides within
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64 | the <quote>File systems</quote> menu and is normally enabled by default.</para>
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65 |
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66 | <note><para>NPTL requires the kernel to be compiled with GCC 3.x, in this case
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67 | &gcc-version;. Compiling with 2.95.x is known to cause failures in the glibc
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68 | testsuite, so do <emphasis>not</emphasis> compile the kernel with gcc 2.95.x
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69 | unless you know what you're getting yourself into.</para></note>
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70 |
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71 | <para>Compile the kernel image and modules:</para>
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72 |
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73 | <screen><userinput>make</userinput></screen>
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74 |
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75 | <para>If you intend to use kernel modules, you will need an
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76 | <filename>/etc/modprobe.conf</filename> file. Information pertaining
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77 | to modules and to kernel configuration in general may be found in the
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78 | kernel documentation, which is found in the
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79 | <filename>linux-&linux-version;/Documentation</filename> directory. The
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80 | modules.conf man page and the kernel HOWTO at
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81 | <ulink url="http://www.tldp.org/HOWTO/Kernel-HOWTO.html"/> may also be of
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82 | interest to you.</para>
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83 |
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84 | <para>Install the modules:</para>
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85 |
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86 | <screen><userinput>make modules_install</userinput></screen>
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87 |
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88 | <para>If you have a lot of modules and very little space, you may want to
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89 | consider stripping and compressing the modules. For most people such compression
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90 | isn't worth the trouble, but if you're really pressed for space, then have a look at
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91 | <ulink url="http://www.linux-mips.org/archives/linux-mips/2002-04/msg00031.html"/>.</para>
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92 |
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93 | <para>Kernel compilation has finished but more steps are required to complete
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94 | the installation. Some files need to be copied to the <filename>/boot</filename>
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95 | directory.</para>
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96 |
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97 | <para>The path to the kernel image may vary depending on the platform you're
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98 | using. Issue the following command to install the kernel:</para>
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99 |
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100 | <screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
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101 |
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102 | <para><filename>System.map</filename> is a symbol file for the kernel. It maps
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103 | the function entry points of every function in the kernel API (Application Programming Interface), as well as the
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104 | addresses of the kernel data structures for the running kernel. Issue the
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105 | following command to install the map file:</para>
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106 |
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107 | <screen><userinput>cp System.map /boot/System.map-&linux-version;</userinput></screen>
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108 |
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109 | <para><filename>.config</filename> is the kernel configuration file that was
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110 | produced by the <command>make menuconfig</command> step above. It contains all
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111 | the config selections for the kernel that was just compiled. It's a good idea
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112 | to keep this file for future reference:</para>
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113 |
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114 | <screen><userinput>cp .config /boot/config-&linux-version;</userinput></screen>
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115 |
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116 | <para>It is important to note that the files in the kernel source directory are
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117 | not owned by <emphasis>root</emphasis>. Whenever you unpack a package as user
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118 | <emphasis>root</emphasis> (like we did here inside chroot), the files end up
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119 | having the user and group IDs of whatever they were on the packager's computer.
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120 | This is usually not a problem for any other package you install because you
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121 | remove the source tree after the installation. But the Linux source tree is
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122 | often kept around for a long time, so there's a chance that whatever user ID
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123 | the packager used will be assigned to somebody on your machine and then that
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124 | person would have write access to the kernel source.</para>
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125 |
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126 | <para>If you are going to keep the kernel source tree around, you may want to
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127 | run <userinput>chown -R 0:0</userinput> on the
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128 | <filename>linux-&linux-version;</filename> directory to ensure all files are
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129 | owned by user <emphasis>root</emphasis>.</para>
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130 |
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131 | </sect2>
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132 |
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133 |
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134 | <sect2 id="contents-kernel" role="content"><title>Contents of Linux</title>
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135 |
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136 | <segmentedlist>
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137 | <segtitle>Installed files</segtitle>
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138 | <seglistitem><seg>the kernel, the kernel headers,
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139 | and the System.map</seg></seglistitem>
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140 | </segmentedlist>
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141 |
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142 | <variablelist><title>Short descriptions</title>
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143 |
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144 | <varlistentry>
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145 | <term id="kernel">The <emphasis>kernel</emphasis></term>
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146 | <listitem>
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147 | <indexterm zone="ch-bootable-kernel kernel"><primary sortas="b-kernel">kernel</primary></indexterm>
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148 | <para>is the engine of your GNU/Linux system.
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149 | When switching on your box, the kernel is the first part of your operating
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150 | system that gets loaded. It detects and initializes all the components of your
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151 | computer's hardware, then makes these components available as a tree of files
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152 | to the software, and turns a single CPU into a multi-tasking machine capable
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153 | of running scores of programs seemingly at the same time.</para>
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154 | </listitem>
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155 | </varlistentry>
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156 |
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157 | <varlistentry>
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158 | <term id="kernel-headers">The <emphasis>kernel headers</emphasis></term>
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159 | <listitem>
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160 | <indexterm zone="ch-bootable-kernel kernel-headers"><primary sortas="e-kernel-headers">kernel headers</primary></indexterm>
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161 | <para>define the interface to the
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162 | services that the kernel provides. The headers in your system's
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163 | <filename>include</filename> directory should <emphasis>always</emphasis> be
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164 | the ones against which Glibc was compiled and should therefore
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165 | <emphasis>not</emphasis> be replaced when upgrading the kernel.</para>
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166 | </listitem>
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167 | </varlistentry>
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168 |
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169 | <varlistentry>
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170 | <term id="System.map"><filename>System.map</filename></term>
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171 | <listitem>
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172 | <indexterm zone="ch-bootable-kernel System.map"><primary sortas="e-/boot/System.map">/boot/System.map</primary></indexterm>
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173 | <para>is a list of addresses and symbols. It maps the entry points and addresses
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174 | of all the functions and data structures in the kernel.</para>
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175 | </listitem>
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176 | </varlistentry>
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177 | </variablelist>
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178 |
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179 | </sect2>
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180 |
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181 | </sect1>
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