| 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-bootable-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-bootable-kernel">
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| 20 | <primary sortas="a-Linux">Linux</primary>
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| 21 | </indexterm>
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| 22 |
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| 23 | <sect2 role="package">
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| 24 | <title/>
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| 25 |
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| 26 | <para>The Linux package contains the Linux kernel.</para>
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| 27 |
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| 28 | <segmentedlist>
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| 29 | <segtitle>&buildtime;</segtitle>
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| 30 | <segtitle>&diskspace;</segtitle>
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| 31 |
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| 32 | <seglistitem>
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| 33 | <seg>&linux-knl-sbu;</seg>
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| 34 | <seg>&linux-knl-du;</seg>
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| 35 | </seglistitem>
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| 36 | </segmentedlist>
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| 37 |
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| 38 | </sect2>
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| 39 |
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| 40 | <sect2 role="installation">
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| 41 | <title>Installation of the kernel</title>
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| 42 |
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| 43 | <para>Building the kernel involves a few steps—configuration,
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| 44 | compilation, and installation. Read the <filename>README</filename> file
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| 45 | in the kernel source tree for alternative methods to the way this book
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| 46 | configures the kernel.</para>
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| 47 |
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| 48 | <important>
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| 49 | <para>
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| 50 | Building the linux kernel for the first time is one of the most
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| 51 | challenging tasks in LFS. Getting it right depends on the specific
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| 52 | hardware for the target system and your specific needs. There are
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| 53 | almost 12,000 configuration items that are available for the kernel
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| 54 | although only about a third of them are needed for most computers. The
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| 55 | LFS editors recommend that users not familiar with this process follow
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| 56 | the procedures below fairly closely. The objective is to get an
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| 57 | initial system to a point where you can log in at the command line when
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| 58 | you reboot later in <xref linkend="ch-finish-reboot"/>. At this point
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| 59 | optimization and customization is not a goal.
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| 60 | </para>
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| 61 |
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| 62 |
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| 63 | <para>
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| 64 | For general information on kernel configuration see <ulink
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| 65 | url="&hints-root;kernel-configuration.txt"/>. Additional information
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| 66 | about configuring and building the kernel can be found at <ulink
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| 67 | url="&anduin-sources;/kernel-nutshell/"/>.
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| 68 | These references are a bit
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| 69 | dated, but still give a reasonable overview of the process.
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| 70 | </para>
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| 71 |
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| 72 | <para>
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| 73 | If all else fails, you can ask for help on the <ulink
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| 74 | url="https://www.linuxfromscratch.org/mail.html">lfs-support</ulink>
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| 75 | mailing list. Note that subscribing is required in order for the list
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| 76 | to avoid spam.
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| 77 | </para>
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| 78 | </important>
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| 79 |
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| 80 | <para>Prepare for compilation by running the following command:</para>
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| 81 |
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| 82 | <screen><userinput remap="pre">make mrproper</userinput></screen>
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| 83 |
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| 84 | <para>This ensures that the kernel tree is absolutely clean. The
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| 85 | kernel team recommends that this command be issued prior to each
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| 86 | kernel compilation. Do not rely on the source tree being clean after
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| 87 | un-tarring.</para>
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| 88 |
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| 89 | <para>There are several ways to configure the kernel options. Usually,
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| 90 | This is done through a menu-driven interface, for example:</para>
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| 91 |
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| 92 | <screen role="nodump"><userinput>make menuconfig</userinput></screen>
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| 93 |
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| 94 | <variablelist>
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| 95 | <title>The meaning of optional make environment variables:</title>
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| 96 |
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| 97 | <varlistentry>
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| 98 | <term><parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term>
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| 99 | <listitem>
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| 100 | <para>This establishes the locale setting to the one used on the
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| 101 | host. This may be needed for a proper menuconfig ncurses interface
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| 102 | line drawing on a UTF-8 linux text console.</para>
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| 103 |
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| 104 | <para>If used, be sure to replace
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| 105 | <replaceable><host_LANG_value></replaceable> by the value of
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| 106 | the <envar>$LANG</envar> variable from your host. You can
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| 107 | alternatively use instead the host's value of <envar>$LC_ALL</envar>
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| 108 | or <envar>$LC_CTYPE</envar>.</para>
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| 109 | </listitem>
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| 110 | </varlistentry>
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| 111 |
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| 112 | <varlistentry>
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| 113 | <term><command>make menuconfig</command></term>
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| 114 | <listitem>
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| 115 | <para>This launches an ncurses menu-driven interface. For other
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| 116 | (graphical) interfaces, type <command>make help</command>.</para>
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| 117 | </listitem>
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| 118 | </varlistentry>
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| 119 | </variablelist>
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| 120 |
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| 121 | <!-- Support for compiling a keymap into the kernel is deliberately removed -->
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| 122 |
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| 123 |
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| 124 | <note>
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| 125 | <para>A good starting place for setting up the kernel configuration is to
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| 126 | run <command>make defconfig</command>. This will set the base
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| 127 | configuration to a good state that takes your current system architecture
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| 128 | into account.</para>
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| 129 |
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| 130 | <para>Be sure to enable/disable/set the following features or the system might
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| 131 | not work correctly or boot at all:</para>
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| 132 |
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| 133 | <screen role="nodump" revision="sysv">General setup --->
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| 134 | [ ] Compile the kernel with warnings as errors [CONFIG_WERROR]
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| 135 | CPU/Task time and stats accounting --->
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| 136 | [*] Pressure stall information tracking [CONFIG_PSI]
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| 137 | [ ] Require boot parameter to enable pressure stall information tracking
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| 138 | [CONFIG_PSI_DEFAULT_DISABLED]
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| 139 | < > Enable kernel headers through /sys/kernel/kheaders.tar.xz [CONFIG_IKHEADERS]
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| 140 | [*] Control Group support [CONFIG_CGROUPS] --->
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| 141 | [*] Memory controller [CONFIG_MEMCG]
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| 142 | [ ] Configure standard kernel features (expert users) [CONFIG_EXPERT]
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| 143 |
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| 144 | Processor type and features --->
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| 145 | [*] Build a relocatable kernel [CONFIG_RELOCATABLE]
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| 146 | [*] Randomize the address of the kernel image (KASLR) [CONFIG_RANDOMIZE_BASE]
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| 147 |
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| 148 | General architecture-dependent options --->
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| 149 | [*] Stack Protector buffer overflow detection [CONFIG_STACKPROTECTOR]
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| 150 | [*] Strong Stack Protector [CONFIG_STACKPROTECTOR_STRONG]
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| 151 |
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| 152 | Device Drivers --->
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| 153 | Generic Driver Options --->
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| 154 | [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
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| 155 | [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
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| 156 | [*] Automount devtmpfs at /dev, after the kernel mounted the rootfs
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| 157 | [CONFIG_DEVTMPFS_MOUNT]
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| 158 | Graphics support --->
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| 159 | Frame buffer Devices --->
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| 160 | <*> Support for frame buffer devices --->
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| 161 | Console display driver support --->
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| 162 | [*] Framebuffer Console support [CONFIG_FRAMEBUFFER_CONSOLE]</screen>
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| 163 |
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| 164 | <screen role="nodump" revision="systemd">
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| 165 | General setup --->
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| 166 | [ ] Compile the kernel with warnings as errors [CONFIG_WERROR]
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| 167 | [ ] Auditing Support [CONFIG_AUDIT]
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| 168 | CPU/Task time and stats accounting --->
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| 169 | [*] Pressure stall information tracking [CONFIG_PSI]
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| 170 | [ ] Require boot parameter to enable pressure stall information tracking
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| 171 | [CONFIG_PSI_DEFAULT_DISABLED]
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| 172 | < > Enable kernel headers through /sys/kernel/kheaders.tar.xz [CONFIG_IKHEADERS]
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| 173 | [*] Control Group support [CONFIG_CGROUPS] --->
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| 174 | [*] Memory controller [CONFIG_MEMCG]
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| 175 | [ ] Configure standard kernel features (expert users) [CONFIG_EXPERT]
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| 176 |
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| 177 | Processor type and features --->
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| 178 | [*] Build a relocatable kernel [CONFIG_RELOCATABLE]
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| 179 | [*] Randomize the address of the kernel image (KASLR) [CONFIG_RANDOMIZE_BASE]
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| 180 |
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| 181 | General architecture-dependent options --->
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| 182 | [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP]
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| 183 | [*] Stack Protector buffer overflow detection [CONFIG_STACKPROTECTOR]
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| 184 | [*] Strong Stack Protector [CONFIG_STACKPROTECTOR_STRONG]
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| 185 |
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| 186 | [*] Networking support ---> [CONFIG_NET]
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| 187 | Networking options --->
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| 188 | [*] TCP/IP networking [CONFIG_INET]
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| 189 | <*> The IPv6 protocol [CONFIG_IPV6]
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| 190 |
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| 191 | Device Drivers --->
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| 192 | Generic Driver Options --->
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| 193 | [ ] Support for uevent helper [CONFIG_UEVENT_HELPER]
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| 194 | [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS]
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| 195 | [*] Automount devtmpfs at /dev, after the kernel mounted the rootfs
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| 196 | [CONFIG_DEVTMPFS_MOUNT]
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| 197 | Firmware Loader --->
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| 198 | [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER]
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| 199 | Firmware Drivers --->
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| 200 | [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID]
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| 201 | Graphics support --->
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| 202 | Frame buffer Devices --->
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| 203 | <*> Support for frame buffer devices --->
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| 204 | Console display driver support --->
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| 205 | [*] Framebuffer Console support [CONFIG_FRAMEBUFFER_CONSOLE]
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| 206 |
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| 207 | File systems --->
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| 208 | [*] Inotify support for userspace [CONFIG_INOTIFY_USER]
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| 209 | Pseudo filesystems --->
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| 210 | [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL]</screen>
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| 211 |
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| 212 | <para>Enable some additional features if you are building a 64-bit
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| 213 | system. If you are using menuconfig, enable them in the order of
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| 214 | <parameter>CONFIG_PCI_MSI</parameter> first, then
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| 215 | <parameter>CONFIG_IRQ_REMAP</parameter>, at last
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| 216 | <parameter>CONFIG_X86_X2APIC</parameter> because an option only
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| 217 | shows up after its dependencies are selected.</para>
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| 218 |
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| 219 | <screen role="nodump">Processor type and features --->
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| 220 | [*] Support x2apic [CONFIG_X86_X2APIC]
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| 221 |
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| 222 | Device Drivers --->
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| 223 | [*] PCI Support ---> [CONFIG_PCI]
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| 224 | [*] Message Signaled Interrupts (MSI and MSI-X) [CONFIG_PCI_MSI]
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| 225 | [*] IOMMU Hardware Support ---> [CONFIG_IOMMU_SUPPORT]
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| 226 | [*] Support for Interrupt Remapping [CONFIG_IRQ_REMAP]</screen>
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| 227 |
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| 228 | <para>If you are building a 32-bit system running on a hardware
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| 229 | with RAM more than 4GB, adjust the configuration so the kernel will
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| 230 | be able to use up to 64GB physical RAM:</para>
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| 231 |
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| 232 | <screen role="nodump">Processor type and features --->
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| 233 | High Memory Support --->
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| 234 | (X) 64GB [CONFIG_HIGHMEM64G]</screen>
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| 235 |
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| 236 | <para>If the partition for the LFS system is in a NVME SSD (i. e. the
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| 237 | device node for the partition is <filename>/dev/nvme*</filename>
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| 238 | instead of <filename>/dev/sd*</filename>), enable NVME support or
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| 239 | the LFS system won't boot:</para>
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| 240 |
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| 241 | <screen role="nodump">Device Drivers --->
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| 242 | NVME Support --->
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| 243 | <*> NVM Express block device [CONFIG_BLK_DEV_NVME]</screen>
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| 244 | </note>
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| 245 |
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| 246 | <note revision="systemd">
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| 247 | <para>While "The IPv6 Protocol" is not strictly
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| 248 | required, it is highly recommended by the systemd developers.</para>
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| 249 | </note>
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| 250 |
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| 251 | <para>There are several other options that may be desired
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| 252 | depending on the requirements for the system. For a list of options needed
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| 253 | for BLFS packages, see the <ulink
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| 254 | url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS
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| 255 | Index of Kernel Settings</ulink>.</para>
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| 256 |
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| 257 | <note>
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| 258 | <para>If your host hardware is using UEFI and you wish to boot the
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| 259 | LFS system with it, you should adjust some kernel configuration
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| 260 | following <ulink url="&blfs-book;postlfs/grub-setup.html#uefi-kernel">
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| 261 | the BLFS page</ulink> <emphasis role='bold'>even if you'll use the
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| 262 | UEFI bootloader from the host distro</emphasis>.</para>
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| 263 | </note>
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| 264 |
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| 265 | <variablelist>
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| 266 | <title>The rationale for the above configuration items:</title>
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| 267 |
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| 268 | <varlistentry>
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| 269 | <term><parameter>Randomize the address of the kernel image (KASLR)</parameter></term>
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| 270 | <listitem>
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| 271 | <para>Enable ASLR for kernel image, to mitigate some attacks based
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| 272 | on fixed addresses of sensitive data or code in the kernel.</para>
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| 273 | </listitem>
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| 274 | </varlistentry>
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| 275 |
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| 276 | <varlistentry>
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| 277 | <term>
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| 278 | <parameter>
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| 279 | Compile the kernel with warnings as errors
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| 280 | </parameter>
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| 281 | </term>
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| 282 | <listitem>
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| 283 | <para>This may cause building failure if the compiler and/or
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| 284 | configuration are different from those of the kernel
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| 285 | developers.</para>
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| 286 | </listitem>
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| 287 | </varlistentry>
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| 288 |
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| 289 | <varlistentry>
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| 290 | <term>
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| 291 | <parameter>
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| 292 | Enable kernel headers through /sys/kernel/kheaders.tar.xz
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| 293 | </parameter>
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| 294 | </term>
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| 295 | <listitem>
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| 296 | <para>This will require <command>cpio</command> building the kernel.
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| 297 | <command>cpio</command> is not installed by LFS.</para>
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| 298 | </listitem>
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| 299 | </varlistentry>
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| 300 |
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| 301 | <varlistentry>
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| 302 | <term>
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| 303 | <parameter>
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| 304 | Configure standard kernel features (expert users)
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| 305 | </parameter>
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| 306 | </term>
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| 307 | <listitem>
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| 308 | <para>This will make some options show up in the configuration
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| 309 | interface but changing those options may be dangerous. Do not use
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| 310 | this unless you know what you are doing.</para>
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| 311 | </listitem>
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| 312 | </varlistentry>
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| 313 |
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| 314 | <varlistentry>
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| 315 | <term><parameter>Strong Stack Protector</parameter></term>
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| 316 | <listitem>
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| 317 | <para>Enable SSP for the kernel. We've enabled it for the entire
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| 318 | userspace with <parameter>--enable-default-ssp</parameter>
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| 319 | configuring GCC, but the kernel does not use GCC default setting
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| 320 | for SSP. We enable it explicitly here.</para>
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| 321 | </listitem>
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| 322 | </varlistentry>
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| 323 |
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| 324 | <varlistentry>
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| 325 | <term><parameter>Support for uevent helper</parameter></term>
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| 326 | <listitem>
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| 327 | <para>Having this option set may interfere with device
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| 328 | management when using Udev.</para>
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| 329 | </listitem>
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| 330 | </varlistentry>
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| 331 |
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| 332 | <varlistentry>
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| 333 | <term><parameter>Maintain a devtmpfs</parameter></term>
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| 334 | <listitem>
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| 335 | <para>This will create automated device nodes which are populated by the
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| 336 | kernel, even without Udev running. Udev then runs on top of this,
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| 337 | managing permissions and adding symlinks. This configuration
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| 338 | item is required for all users of Udev.</para>
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| 339 | </listitem>
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| 340 | </varlistentry>
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| 341 |
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| 342 | <varlistentry>
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| 343 | <term><parameter>Automount devtmpfs at /dev</parameter></term>
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| 344 | <listitem>
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| 345 | <para>This will mount the kernel view of the devices on /dev
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| 346 | upon switching to root filesystem just before starting
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| 347 | init.</para>
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| 348 | </listitem>
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| 349 | </varlistentry>
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| 350 |
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| 351 | <varlistentry>
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| 352 | <term><parameter>Framebuffer Console support</parameter></term>
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| 353 | <listitem>
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| 354 | <para>This is needed to display the Linux console on a frame
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| 355 | buffer device. To allow the kernel to print debug messages at an
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| 356 | early boot stage, it shouldn't be built as a kernel module
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| 357 | unless an initramfs will be used. And, if
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| 358 | <option>CONFIG_DRM</option> (Direct Rendering Manager) is enabled,
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| 359 | it's likely <option>CONFIG_DRM_FBDEV_EMULATION</option> (Enable
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| 360 | legacy fbdev support for your modesetting driver) should be
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| 361 | enabled as well.</para>
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| 362 | </listitem>
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| 363 | </varlistentry>
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| 364 |
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| 365 | <varlistentry>
|
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| 366 | <term><parameter>Support x2apic</parameter></term>
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| 367 | <listitem>
|
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| 368 | <para>Support running the interrupt controller of 64-bit x86
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| 369 | processors in x2APIC mode. x2APIC may be enabled by firmware on
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| 370 | 64-bit x86 systems, and a kernel without this option enabled will
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| 371 | panic on boot if x2APIC is enabled by firmware. This option has
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| 372 | has no effect, but also does no harm if x2APIC is disabled by the
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| 373 | firmware.</para>
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| 374 | </listitem>
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| 375 | </varlistentry>
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| 376 |
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| 377 | </variablelist>
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| 378 |
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| 379 | <para>Alternatively, <command>make oldconfig</command> may be more
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| 380 | appropriate in some situations. See the <filename>README</filename>
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| 381 | file for more information.</para>
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| 382 |
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| 383 | <para>If desired, skip kernel configuration by copying the kernel
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| 384 | config file, <filename>.config</filename>, from the host system
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| 385 | (assuming it is available) to the unpacked <filename
|
|---|
| 386 | class="directory">linux-&linux-version;</filename> directory. However,
|
|---|
| 387 | we do not recommend this option. It is often better to explore all the
|
|---|
| 388 | configuration menus and create the kernel configuration from
|
|---|
| 389 | scratch.</para>
|
|---|
| 390 |
|
|---|
| 391 | <para>Compile the kernel image and modules:</para>
|
|---|
| 392 |
|
|---|
| 393 | <screen><userinput remap="make">make</userinput></screen>
|
|---|
| 394 |
|
|---|
| 395 | <para>If using kernel modules, module configuration in <filename
|
|---|
| 396 | class="directory">/etc/modprobe.d</filename> may be required.
|
|---|
| 397 | Information pertaining to modules and kernel configuration is
|
|---|
| 398 | located in <xref linkend="ch-config-udev"/> and in the kernel
|
|---|
| 399 | documentation in the <filename
|
|---|
| 400 | class="directory">linux-&linux-version;/Documentation</filename> directory.
|
|---|
| 401 | Also, <filename>modprobe.d(5)</filename> may be of interest.</para>
|
|---|
| 402 |
|
|---|
| 403 | <para>Unless module support has been disabled in the kernel configuration,
|
|---|
| 404 | install the modules with:</para>
|
|---|
| 405 |
|
|---|
| 406 | <screen><userinput remap="install">make modules_install</userinput></screen>
|
|---|
| 407 |
|
|---|
| 408 | <para>After kernel compilation is complete, additional steps are
|
|---|
| 409 | required to complete the installation. Some files need to be copied to
|
|---|
| 410 | the <filename class="directory">/boot</filename> directory.</para>
|
|---|
| 411 |
|
|---|
| 412 | <caution>
|
|---|
| 413 | <para>If you've decided to use a separate &boot-dir; partition for the
|
|---|
| 414 | LFS system (maybe sharing a &boot-dir; partition with the host
|
|---|
| 415 | distro) , the files copied below should go there. The easiest way to
|
|---|
| 416 | do that is to create the entry for &boot-dir; in &fstab; first (read
|
|---|
| 417 | the previous section for details), then issue the following command
|
|---|
| 418 | as the &root; user in the
|
|---|
| 419 | <emphasis>chroot environment</emphasis>:</para>
|
|---|
| 420 |
|
|---|
| 421 | <screen role="nodump"><userinput>mount /boot</userinput></screen>
|
|---|
| 422 |
|
|---|
| 423 | <para>The path to the device node is omitted in the command because
|
|---|
| 424 | <command>mount</command> can read it from &fstab;.</para>
|
|---|
| 425 | </caution>
|
|---|
| 426 |
|
|---|
| 427 | <para>The path to the kernel image may vary depending on the platform being
|
|---|
| 428 | used. The filename below can be changed to suit your taste, but the stem of
|
|---|
| 429 | the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
|
|---|
| 430 | the automatic setup of the boot process described in the next section. The
|
|---|
| 431 | following command assumes an x86 architecture:</para>
|
|---|
| 432 |
|
|---|
| 433 | <screen><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
|
|---|
| 434 |
|
|---|
| 435 | <para><filename>System.map</filename> is a symbol file for the kernel.
|
|---|
| 436 | It maps the function entry points of every function in the kernel API,
|
|---|
| 437 | as well as the addresses of the kernel data structures for the running
|
|---|
| 438 | kernel. It is used as a resource when investigating kernel problems.
|
|---|
| 439 | Issue the following command to install the map file:</para>
|
|---|
| 440 |
|
|---|
| 441 | <screen><userinput remap="install">cp -iv System.map /boot/System.map-&linux-version;</userinput></screen>
|
|---|
| 442 |
|
|---|
| 443 | <para>The kernel configuration file <filename>.config</filename>
|
|---|
| 444 | produced by the <command>make menuconfig</command> step
|
|---|
| 445 | above contains all the configuration selections for the kernel
|
|---|
| 446 | that was just compiled. It is a good idea to keep this file for future
|
|---|
| 447 | reference:</para>
|
|---|
| 448 |
|
|---|
| 449 | <screen><userinput remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen>
|
|---|
| 450 |
|
|---|
| 451 | <para>Install the documentation for the Linux kernel:</para>
|
|---|
| 452 |
|
|---|
| 453 | <screen><userinput remap="install">cp -r Documentation -T /usr/share/doc/linux-&linux-version;</userinput></screen>
|
|---|
| 454 |
|
|---|
| 455 | <para>It is important to note that the files in the kernel source
|
|---|
| 456 | directory are not owned by <emphasis>root</emphasis>. Whenever a
|
|---|
| 457 | package is unpacked as user <emphasis>root</emphasis> (like we did
|
|---|
| 458 | inside chroot), the files have the user and group IDs of whatever
|
|---|
| 459 | they were on the packager's computer. This is usually not a problem
|
|---|
| 460 | for any other package to be installed because the source tree is
|
|---|
| 461 | removed after the installation. However, the Linux source tree is
|
|---|
| 462 | often retained for a long time. Because of this, there is a chance
|
|---|
| 463 | that whatever user ID the packager used will be assigned to somebody
|
|---|
| 464 | on the machine. That person would then have write access to the kernel
|
|---|
| 465 | source.</para>
|
|---|
| 466 |
|
|---|
| 467 | <note>
|
|---|
| 468 | <para>In many cases, the configuration of the kernel will need to be
|
|---|
| 469 | updated for packages that will be installed later in BLFS. Unlike
|
|---|
| 470 | other packages, it is not necessary to remove the kernel source tree
|
|---|
| 471 | after the newly built kernel is installed.</para>
|
|---|
| 472 |
|
|---|
| 473 | <para>If the kernel source tree is going to be retained, run
|
|---|
| 474 | <command>chown -R 0:0</command> on the <filename
|
|---|
| 475 | class="directory">linux-&linux-version;</filename> directory to ensure
|
|---|
| 476 | all files are owned by user <emphasis>root</emphasis>.</para>
|
|---|
| 477 | </note>
|
|---|
| 478 |
|
|---|
| 479 | <warning>
|
|---|
| 480 | <para>Some kernel documentation recommends creating a symlink from
|
|---|
| 481 | <filename class="symlink">/usr/src/linux</filename> pointing to the kernel
|
|---|
| 482 | source directory. This is specific to kernels prior to the 2.6 series and
|
|---|
| 483 | <emphasis>must not</emphasis> be created on an LFS system as it can cause
|
|---|
| 484 | problems for packages you may wish to build once your base LFS system is
|
|---|
| 485 | complete.</para>
|
|---|
| 486 | </warning>
|
|---|
| 487 |
|
|---|
| 488 | <warning>
|
|---|
| 489 | <para>The headers in the system's <filename
|
|---|
| 490 | class="directory">include</filename> directory (<filename
|
|---|
| 491 | class="directory">/usr/include</filename>) should
|
|---|
| 492 | <emphasis>always</emphasis> be the ones against which Glibc was compiled,
|
|---|
| 493 | that is, the sanitised headers installed in <xref
|
|---|
| 494 | linkend="ch-tools-linux-headers"/>. Therefore, they should
|
|---|
| 495 | <emphasis>never</emphasis> be replaced by either the raw kernel headers
|
|---|
| 496 | or any other kernel sanitized headers.</para>
|
|---|
| 497 | </warning>
|
|---|
| 498 |
|
|---|
| 499 | </sect2>
|
|---|
| 500 |
|
|---|
| 501 | <sect2 id="conf-modprobe" role="configuration">
|
|---|
| 502 | <title>Configuring Linux Module Load Order</title>
|
|---|
| 503 |
|
|---|
| 504 | <indexterm zone="conf-modprobe">
|
|---|
| 505 | <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
|
|---|
| 506 | </indexterm>
|
|---|
| 507 |
|
|---|
| 508 | <para>Most of the time Linux modules are loaded automatically, but
|
|---|
| 509 | sometimes it needs some specific direction. The program that loads
|
|---|
| 510 | modules, <command>modprobe</command> or <command>insmod</command>, uses
|
|---|
| 511 | <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file
|
|---|
| 512 | needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and
|
|---|
| 513 | uhci_hcd) have been built as modules, they will be loaded in the correct
|
|---|
| 514 | order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order
|
|---|
| 515 | to avoid a warning being output at boot time.</para>
|
|---|
| 516 |
|
|---|
| 517 | <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
|
|---|
| 518 | the following:</para>
|
|---|
| 519 |
|
|---|
| 520 | <screen><userinput>install -v -m755 -d /etc/modprobe.d
|
|---|
| 521 | cat > /etc/modprobe.d/usb.conf << "EOF"
|
|---|
| 522 | <literal># Begin /etc/modprobe.d/usb.conf
|
|---|
| 523 |
|
|---|
| 524 | install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
|
|---|
| 525 | install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
|
|---|
| 526 |
|
|---|
| 527 | # End /etc/modprobe.d/usb.conf</literal>
|
|---|
| 528 | EOF</userinput></screen>
|
|---|
| 529 |
|
|---|
| 530 | </sect2>
|
|---|
| 531 |
|
|---|
| 532 | <sect2 id="contents-kernel" role="content">
|
|---|
| 533 | <title>Contents of Linux</title>
|
|---|
| 534 |
|
|---|
| 535 | <segmentedlist>
|
|---|
| 536 | <segtitle>Installed files</segtitle>
|
|---|
| 537 | <segtitle>Installed directories</segtitle>
|
|---|
| 538 |
|
|---|
| 539 | <seglistitem>
|
|---|
| 540 | <seg>config-&linux-version;,
|
|---|
| 541 | vmlinuz-&linux-version;-lfs-&version;,
|
|---|
| 542 | and System.map-&linux-version;</seg>
|
|---|
| 543 | <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
|
|---|
| 544 | </seglistitem>
|
|---|
| 545 | </segmentedlist>
|
|---|
| 546 |
|
|---|
| 547 | <variablelist>
|
|---|
| 548 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
|
|---|
| 549 | <?dbfo list-presentation="list"?>
|
|---|
| 550 | <?dbhtml list-presentation="table"?>
|
|---|
| 551 |
|
|---|
| 552 | <varlistentry id="config">
|
|---|
| 553 | <term><filename>config-&linux-version;</filename></term>
|
|---|
| 554 | <listitem>
|
|---|
| 555 | <para>Contains all the configuration selections for the kernel</para>
|
|---|
| 556 | <indexterm zone="ch-bootable-kernel config">
|
|---|
| 557 | <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
|
|---|
| 558 | </indexterm>
|
|---|
| 559 | </listitem>
|
|---|
| 560 | </varlistentry>
|
|---|
| 561 |
|
|---|
| 562 | <varlistentry id="lfskernel">
|
|---|
| 563 | <term><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term>
|
|---|
| 564 | <listitem>
|
|---|
| 565 | <para>The engine of the Linux system. When turning on the computer,
|
|---|
| 566 | the kernel is the first part of the operating system that gets loaded.
|
|---|
| 567 | It detects and initializes all components of the computer's hardware,
|
|---|
| 568 | then makes these components available as a tree of files to the
|
|---|
| 569 | software and turns a single CPU into a multitasking machine capable
|
|---|
| 570 | of running scores of programs seemingly at the same time</para>
|
|---|
| 571 | <indexterm zone="ch-bootable-kernel lfskernel">
|
|---|
| 572 | <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
|
|---|
| 573 | </indexterm>
|
|---|
| 574 | </listitem>
|
|---|
| 575 | </varlistentry>
|
|---|
| 576 |
|
|---|
| 577 | <varlistentry id="System.map">
|
|---|
| 578 | <term><filename>System.map-&linux-version;</filename></term>
|
|---|
| 579 | <listitem>
|
|---|
| 580 | <para>A list of addresses and symbols; it maps the entry points and
|
|---|
| 581 | addresses of all the functions and data structures in the
|
|---|
| 582 | kernel</para>
|
|---|
| 583 | <indexterm zone="ch-bootable-kernel System.map">
|
|---|
| 584 | <primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
|
|---|
| 585 | </indexterm>
|
|---|
| 586 | </listitem>
|
|---|
| 587 | </varlistentry>
|
|---|
| 588 |
|
|---|
| 589 | </variablelist>
|
|---|
| 590 |
|
|---|
| 591 | </sect2>
|
|---|
| 592 |
|
|---|
| 593 | </sect1>
|
|---|
