[f58cbc1] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 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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| 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-tools-kernel" role="wrap">
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| 9 | <?dbhtml filename="kernel.html"?>
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| 10 |
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| 11 | <sect1info condition="script">
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| 12 | <productname>kernel</productname>
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| 13 | <productnumber>&linux-version;</productnumber>
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| 14 | <address>&linux-url;</address>
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| 15 | </sect1info>
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| 16 |
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| 17 | <title>Linux-&linux-version;</title>
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| 18 |
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| 19 | <indexterm zone="ch-tools-kernel">
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| 20 | <primary sortas="a-Linux">Linux</primary>
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| 21 | <secondary>tools</secondary>
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| 22 | </indexterm>
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| 23 |
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| 24 | <sect2 role="package">
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| 25 | <title/>
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| 26 |
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| 27 | <para>The Linux package contains the Linux kernel.</para>
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| 28 |
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| 29 | <segmentedlist>
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| 30 | <segtitle>&buildtime;</segtitle>
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| 31 | <segtitle>&diskspace;</segtitle>
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| 32 |
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| 33 | <seglistitem>
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| 34 | <seg>&linux-tmp-sbu;</seg>
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| 35 | <seg>&linux-tmp-du;</seg>
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| 36 | </seglistitem>
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| 37 | </segmentedlist>
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| 38 |
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| 39 | </sect2>
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| 40 |
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| 41 | <sect2 role="installation">
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| 42 | <title>Installation of the kernel</title>
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| 43 |
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| 44 | <para>Building the kernel involves a few steps—configuration,
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| 45 | compilation, and installation. Read the <filename>README</filename> file
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| 46 | in the kernel source tree for alternative methods to the way this book
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| 47 | configures the kernel.</para>
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| 48 |
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| 49 | <para>Prepare for compilation by running the following command:</para>
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| 50 |
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| 51 | <screen><userinput remap="pre">make mrproper</userinput></screen>
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| 52 |
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| 53 | <para>This ensures that the kernel tree is absolutely clean. The
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| 54 | kernel team recommends that this command be issued prior to each
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| 55 | kernel compilation. Do not rely on the source tree being clean after
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| 56 | un-tarring.</para>
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| 57 |
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| 58 | <para>There are several ways to configure the kernel options. Usually,
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| 59 | This is done through a menu-driven interface, for example:</para>
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| 60 |
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[4f2d91dc] | 61 | <screen role="nodump"><userinput>make ARCH=<replaceable>x86</replaceable> CROSS_COMPILE=$LFS_TGT- menuconfig</userinput></screen>
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[f58cbc1] | 62 |
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| 63 | <variablelist>
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| 64 | <title>The meaning of make environment variables:</title>
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| 65 |
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| 66 | <varlistentry>
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| 67 | <term><command>ARCH=x86</command></term>
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| 68 | <listitem>
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[4f2d91dc] | 69 | <para>Configure the kernel for running on the target machine.
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| 70 | Replace <replaceable>x86</replaceable> with a value suitable
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| 71 | for your target machine if it's not a 32-bit or 64-bit x86.</para>
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[f58cbc1] | 72 | </listitem>
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| 73 | </varlistentry>
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| 74 |
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| 75 | <varlistentry>
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| 76 | <term><command>CROSS_COMPILE=$LFS_TGT-</command></term>
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| 77 | <listitem>
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| 78 | <para>Build the kernel with Binutils and GCC built in
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| 79 | <xref linkend='chapter-cross-tools'/>.</para>
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| 80 | </listitem>
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| 81 | </varlistentry>
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| 82 |
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| 83 | <varlistentry>
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| 84 | <term><command>menuconfig</command></term>
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| 85 | <listitem>
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| 86 | <para>This launches an ncurses menu-driven interface. For other
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| 87 | (graphical) interfaces, type <command>make help</command>.</para>
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| 88 | </listitem>
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| 89 | </varlistentry>
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| 90 |
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| 91 | <varlistentry>
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| 92 | <term>(optional) <parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term>
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| 93 | <listitem>
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| 94 | <para>This establishes the locale setting to the one used on the
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| 95 | host. This may be needed for a proper menuconfig ncurses interface
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| 96 | line drawing on a UTF-8 linux text console.</para>
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| 97 |
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| 98 | <para>If used, be sure to replace
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| 99 | <replaceable><host_LANG_value></replaceable> by the value of
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| 100 | the <envar>$LANG</envar> variable from your host. You can
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| 101 | alternatively use instead the host's value of <envar>$LC_ALL</envar>
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| 102 | or <envar>$LC_CTYPE</envar>.</para>
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| 103 | </listitem>
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| 104 | </varlistentry>
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| 105 |
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| 106 | </variablelist>
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| 107 |
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| 108 | <note>
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| 109 |
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| 110 | <para>A good starting place for setting up the kernel configuration is to
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| 111 | run <command>make ARCH=x86 CROSS_COMPILE=$LFS_TGT- defconfig</command>. This will set the base
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| 112 | configuration to a good state that takes your target system architecture
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| 113 | into account.</para>
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| 114 |
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| 115 | </note>
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| 116 |
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| 117 | <para>Read <xref linkend='ch-bootable-kernel'/> for more information
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| 118 | about kernel configuration. You should enable or disable some kernel
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| 119 | configuration options now:</para>
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| 120 |
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| 121 | <variablelist>
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| 122 | <title>Kernel configuration options and explanation:</title>
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| 123 |
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| 124 | <varlistentry>
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| 125 | <term>Set <parameter>CONFIG_MODULES=n</parameter></term>
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| 126 | <listitem>
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| 127 | <para>Modular kernel needs <command>modprobe</command> tool from
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| 128 | <application>Kmod</application> to load modules, which is not
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| 129 | installed in the temporary system.</para>
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| 130 | </listitem>
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| 131 | </varlistentry>
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| 132 |
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[9673470] | 133 | <varlistentry>
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| 134 | <term>Set <parameter>CONFIG_EXTRA_FIRMWARE="<replaceable>a.bin b.bin</replaceable>"</parameter></term>
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| 135 | <listitem>
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| 136 | <para>Build firmware blobs into the kernel. Some drivers may
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| 137 | require the firmwares to be in-kernel if the driver is not built
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| 138 | as module.</para>
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| 139 | <note>
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| 140 | <para>
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| 141 | The kernel binaries with third-party blobs are not
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| 142 | distributable. If you distribute such a kernel binary to
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| 143 | others, you may violate GPL. It's recommended to remove the
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| 144 | temporary kernel image after you've successfully boot your LFS
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| 145 | system with the new kernel image, which will be installed in
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| 146 | <xref linkend="ch-bootable-kernel"/>.
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| 147 | </para>
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| 148 | </note>
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| 149 | </listitem>
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| 150 | </varlistentry>
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| 151 |
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| 152 | <varlistentry>
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| 153 | <term>Set <parameter>CONFIG_EXTRA_FIRMWARE_DIR="<replaceable>$LFS</replaceable>/lib/firmware"</parameter></term>
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| 154 | <listitem>
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| 155 | <para>The building system will search
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| 156 | <filename class="directory">/lib/firmware</filename> for firmware
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| 157 | blobs in <parameter>CONFIG_EXTRA_FIRMWARE</parameter>. Note that
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| 158 | you'll need to install the needed firmwares into
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| 159 | <filename class="directory">$LFS/lib/firmware</filename> first,
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| 160 | and manually replace <envar>$LFS</envar> with the value in
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| 161 | configuration. The firmwares in
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| 162 | <filename class="directory">$LFS/lib/filename</filename> will be
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| 163 | copied to the target machine along with the system, so kernel and
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| 164 | kernel modules which will be built in
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| 165 | <xref linkend="ch-bootable-kernel"/> can load them without
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| 166 | <parameter>CONFIG_EXTRA_FIRMWARE</parameter>.</para>
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| 167 | </listitem>
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| 168 | </varlistentry>
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| 169 |
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[f58cbc1] | 170 | <varlistentry>
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[8b37712] | 171 | <term>Set <parameter>CONFIG_EXT2=y</parameter>,
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| 172 | <parameter>CONFIG_EXT4=y</parameter>,
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| 173 | and <parameter>CONFIG_VFAT_FS=y</parameter></term>
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[f58cbc1] | 174 | <listitem>
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| 175 | <para>They are needed to access the filesystems we'll make for the
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| 176 | target system.</para>
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| 177 | </listitem>
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| 178 | </varlistentry>
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[8b37712] | 179 |
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| 180 | <varlistentry>
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[dd80883] | 181 | <term>
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| 182 | Set <parameter>CONFIG_MODULE_SIG=n</parameter>,
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| 183 | <parameter>CONFIG_SECURITY=n</parameter>,
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| 184 | <parameter>CONFIG_STACK_VALIDATION=n</parameter>,
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| 185 | <parameter>CONFIG_SYSTEM_TRUSTED_KEYRING=n</parameter>,
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| 186 | and <parameter>CONFIG_SYSTEM_REVOCATION_LIST=n</parameter>
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| 187 | </term>
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[8b37712] | 188 | <listitem>
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| 189 | <para>They are unneeded for the temporary kernel, and they need
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| 190 | additional dependencies which may be unavailable on the host
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| 191 | distro. You can enable them building the kernel for the final LFS
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| 192 | system in Chapter 10 if you need these features.</para>
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| 193 | </listitem>
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| 194 | </varlistentry>
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[f58cbc1] | 195 | </variablelist>
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| 196 |
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| 197 | <para>Compile the kernel image:</para>
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| 198 |
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| 199 | <screen><userinput remap="make">make ARCH=x86 CROSS_COMPILE=$LFS_TGT-</userinput></screen>
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| 200 |
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| 201 | <para>Install the kernel image into the
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| 202 | <filename class="directory">$LFS/boot</filename> directory:</para>
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| 203 |
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[31e8da4] | 204 | <screen><userinput remap="install">install -vm644 arch/x86/boot/bzImage $LFS/boot/vmlinuz</userinput></screen>
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[f58cbc1] | 205 |
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| 206 | </sect2>
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| 207 |
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| 208 | <sect2 role="content">
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| 209 | <title/>
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| 210 |
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| 211 | <para>Details on this package are located in
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| 212 | <xref linkend="contents-kernel" role="."/></para>
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| 213 |
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| 214 | </sect2>
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| 215 |
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| 216 | </sect1>
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