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">
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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 | <para>The Linux package contains the kernel and the header files.</para>
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13 |
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14 | <screen>&buildtime; All default options: 4.20 SBU
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15 | &diskspace; All default options: 181 MB</screen>
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16 |
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17 | <para>Linux installation depends on: Bash, Binutils, Coreutils, Findutils,
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18 | GCC, Glibc, Grep, Gzip, Make, Modutils, Perl, Sed.</para>
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19 |
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20 |
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21 |
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22 | <sect2>
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23 | <title>Installation of the kernel</title>
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24 |
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25 | <para>Building the kernel involves a few steps: configuration, compilation, and
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26 | installation. If you don't like the way this book configures the kernel, view
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27 | the <filename>README</filename> file in the kernel source tree for alternative
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28 | methods.</para>
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29 |
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30 | <para>Prepare for compilation by running the following command:</para>
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31 |
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32 | <screen><userinput>make mrproper</userinput></screen>
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33 |
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34 | <para>This ensures that the kernel tree is absolutely clean. The kernel team
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35 | recommends that this command be issued prior to <emphasis>each</emphasis>
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36 | kernel compilation. You shouldn't 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>Configure the kernel via a menu-driven interface:</para>
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40 |
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41 | <screen><userinput>make menuconfig</userinput></screen>
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42 |
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43 | <para><userinput>make oldconfig</userinput> may be more appropriate in some
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44 | situations. See the <filename>README</filename> file for more
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45 | information.</para>
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46 |
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47 | <para>If you wish, you may skip kernel configuration by simply copying the
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48 | kernel config file, <filename>.config</filename>, from your host system
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49 | (assuming it is available) to the unpacked <filename class="directory">linux-&linux-version;</filename>
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50 | directory. However, we
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51 | don't recommend this option. You're much better off exploring all the
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52 | configuration menus and creating your own kernel configuration from
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53 | scratch.</para>
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54 |
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55 | <para>For POSIX shared memory support, ensure that the kernel config option
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56 | <quote>Virtual memory file system support</quote> is enabled. It resides within
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57 | the <quote>File systems</quote> menu and is normally enabled by default.</para>
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58 |
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59 | <note><para>NPTL requires the kernel to be compiled with GCC 3.x, in this case
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60 | &gcc-version;. Compiling with 2.95.x is known to cause failures in the glibc
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61 | testsuite, so do <emphasis>not</emphasis> compile the kernel with gcc 2.95.x
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62 | unless you know what you're getting yourself into.</para></note>
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63 |
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64 | <para>Compile the kernel image and modules:</para>
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65 |
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66 | <screen><userinput>make</userinput></screen>
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67 |
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68 | <para>If you intend to use kernel modules, you will need an
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69 | <filename>/etc/modprobe.conf</filename> file. Information pertaining
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70 | to modules and to kernel configuration in general may be found in the
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71 | kernel documentation, which is found in the
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72 | <filename>linux-&linux-version;/Documentation</filename> directory. The
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73 | modules.conf man page and the kernel HOWTO at
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74 | <ulink url="http://www.tldp.org/HOWTO/Kernel-HOWTO.html"/> may also be of
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75 | interest to you.</para>
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76 |
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77 | <para>Install the modules:</para>
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78 |
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79 | <screen><userinput>make modules_install</userinput></screen>
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80 |
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81 | <para>If you have a lot of modules and very little space, you may want to
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82 | consider stripping and compressing the modules. For most people such compression
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83 | isn't worth the trouble, but if you're really pressed for space, then have a look at
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84 | <ulink url="http://www.linux-mips.org/archives/linux-mips/2002-04/msg00031.html"/>.</para>
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85 |
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86 | <para>Kernel compilation has finished but more steps are required to complete
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87 | the installation. Some files need to be copied to the <filename>/boot</filename>
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88 | directory.</para>
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89 |
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90 | <para>The path to the kernel image may vary depending on the platform you're
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91 | using. Issue the following command to install the kernel:</para>
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92 |
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93 | <screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen>
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94 |
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95 | <para><filename>System.map</filename> is a symbol file for the kernel. It maps
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96 | the function entry points of every function in the kernel API (Application Programming Interface), as well as the
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97 | addresses of the kernel data structures for the running kernel. Issue the
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98 | following command to install the map file:</para>
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99 |
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100 | <screen><userinput>cp System.map /boot/System.map-&linux-version;</userinput></screen>
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101 |
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102 | <para><filename>.config</filename> is the kernel configuration file that was
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103 | produced by the <command>make menuconfig</command> step above. It contains all
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104 | the config selections for the kernel that was just compiled. It's a good idea
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105 | to keep this file for future reference:</para>
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106 |
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107 | <screen><userinput>cp .config /boot/config-&linux-version;</userinput></screen>
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108 |
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109 | <para>It is important to note that the files in the kernel source directory are
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110 | not owned by <emphasis>root</emphasis>. Whenever you unpack a package as user
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111 | <emphasis>root</emphasis> (like we did here inside chroot), the files end up
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112 | having the user and group IDs of whatever they were on the packager's computer.
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113 | This is usually not a problem for any other package you install because you
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114 | remove the source tree after the installation. But the Linux source tree is
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115 | often kept around for a long time, so there's a chance that whatever user ID
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116 | the packager used will be assigned to somebody on your machine and then that
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117 | person would have write access to the kernel source.</para>
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118 |
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119 | <para>If you are going to keep the kernel source tree around, you may want to
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120 | run <userinput>chown -R 0:0</userinput> on the
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121 | <filename>linux-2.4.25</filename> directory to ensure all files are
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122 | owned by user <emphasis>root</emphasis>.</para>
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123 |
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124 | </sect2>
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125 |
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126 |
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127 | <sect2 id="contents-kernel"><title>Contents of Linux</title>
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128 |
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129 | <para><emphasis>Installed files</emphasis>: the kernel, the kernel headers,
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130 | and the System.map</para>
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131 |
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132 | </sect2>
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133 |
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134 | <sect2><title>Short descriptions</title>
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135 |
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136 | <indexterm zone="ch-bootable-kernel kernel"><primary sortas="b-kernel">kernel</primary></indexterm>
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137 | <para id="kernel">The <emphasis>kernel</emphasis> is the engine of your GNU/Linux system.
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138 | When switching on your box, the kernel is the first part of your operating
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139 | system that gets loaded. It detects and initializes all the components of your
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140 | computer's hardware, then makes these components available as a tree of files
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141 | to the software, and turns a single CPU into a multi-tasking machine capable
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142 | of running scores of programs seemingly at the same time.</para>
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143 |
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144 | <indexterm zone="ch-bootable-kernel kernel-headers"><primary sortas="e-kernel-headers">kernel headers</primary></indexterm>
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145 | <para id="kernel-headers">The <emphasis>kernel headers</emphasis> define the interface to the
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146 | services that the kernel provides. The headers in your system's
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147 | <filename>include</filename> directory should <emphasis>always</emphasis> be
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148 | the ones against which Glibc was compiled and should therefore
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149 | <emphasis>not</emphasis> be replaced when upgrading the kernel.</para>
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150 |
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151 | <indexterm zone="ch-bootable-kernel System.map"><primary sortas="e-/boot/System.map">/boot/System.map</primary></indexterm>
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152 | <para id="System.map">The <filename>System.map</filename> file is a list of addresses and
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153 | symbols. It maps the entry points and addresses of all the functions and data
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154 | structures in the kernel.</para>
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155 |
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156 | </sect2>
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157 |
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158 |
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159 |
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160 | </sect1>
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