mirror of
https://git.linuxfromscratch.org/lfs.git
synced 2025-01-19 21:49:13 +00:00
e9ba8aa85f
Move mounting of /dev to mountvirtfs and ensure /dev gets placed in /etc/mtab. Change fstab and kernel configuration sections to reflect these changes. git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@9710 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
282 lines
12 KiB
XML
282 lines
12 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../general.ent">
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%general-entities;
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]>
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<sect1 id="ch-bootable-kernel" role="wrap">
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<?dbhtml filename="kernel.html"?>
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<sect1info condition="script">
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<productname>linux</productname>
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<productnumber>&linux-version;</productnumber>
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<address>&linux-url;</address>
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</sect1info>
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<title>Linux-&linux-version;</title>
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<indexterm zone="ch-bootable-kernel">
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<primary sortas="a-Linux">Linux</primary>
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</indexterm>
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<sect2 role="package">
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<title/>
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<para>The Linux package contains the Linux kernel.</para>
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<segmentedlist>
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<segtitle>&buildtime;</segtitle>
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<segtitle>&diskspace;</segtitle>
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<seglistitem>
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<seg>&linux-ch8-sbu;</seg>
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<seg>&linux-ch8-du;</seg>
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</seglistitem>
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</segmentedlist>
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</sect2>
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<sect2 role="installation">
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<title>Installation of the kernel</title>
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<para>Building the kernel involves a few steps—configuration,
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compilation, and installation. Read the <filename>README</filename> file
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in the kernel source tree for alternative methods to the way this book
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configures the kernel.</para>
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<para>Prepare for compilation by running the following command:</para>
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<screen><userinput remap="pre">make mrproper</userinput></screen>
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<para>This ensures that the kernel tree is absolutely clean. The
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kernel team recommends that this command be issued prior to each
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kernel compilation. Do not rely on the source tree being clean after
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un-tarring.</para>
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<!-- Support for compiling a keymap into the kernel is deliberately removed -->
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<para>Configure the kernel via a menu-driven interface. For general
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information on kernel configuration see <ulink
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url="&hints-root;kernel-configuration.txt"/>. BLFS has some information
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regarding particular kernel configuration requirements of packages outside
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of LFS at <ulink
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url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>. </para>
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<note><para>Due to recent changes in <application>udev</application>, be sure to
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select:</para>
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<screen role="nodump">Device Drivers --->
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Generic Driver Options --->
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Maintain a devtmpfs filesystem to mount at /dev</screen></note>
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<screen role="nodump"><userinput>make LANG=<replaceable><host_LANG_value></replaceable> LC_ALL= menuconfig</userinput></screen>
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<variablelist>
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<title>The meaning of the make parameters:</title>
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<varlistentry>
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<term><parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term>
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<listitem>
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<para>This establishes the locale setting to the one used on the host.
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This is needed for a proper menuconfig ncurses interface line
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drawing on UTF-8 linux text console.</para>
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<para>Be sure to replace <replaceable><host_LANG_value></replaceable>
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by the value of the <envar>$LANG</envar> variable from your host.
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If not set, you could use instead the host's value of <envar>$LC_ALL</envar>
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or <envar>$LC_CTYPE</envar>.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Alternatively, <command>make oldconfig</command> may be more
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appropriate in some situations. See the <filename>README</filename>
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file for more information.</para>
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<para>If desired, skip kernel configuration by copying the kernel
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config file, <filename>.config</filename>, from the host system
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(assuming it is available) to the unpacked <filename
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class="directory">linux-&linux-version;</filename> directory. However,
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we do not recommend this option. It is often better to explore all the
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configuration menus and create the kernel configuration from
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scratch.</para>
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<para>Compile the kernel image and modules:</para>
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<screen><userinput remap="make">make</userinput></screen>
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<para>If using kernel modules, module configuration in <filename
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class="directory">/etc/modprobe.d</filename> may be required.
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Information pertaining to modules and kernel configuration is
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located in <xref linkend="ch-scripts-udev"/> and in the kernel
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documentation in the <filename
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class="directory">linux-&linux-version;/Documentation</filename> directory.
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Also, <filename>modprobe.conf(5)</filename> may be of interest.</para>
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<para>Install the modules, if the kernel configuration uses them:</para>
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<screen><userinput remap="install">make modules_install</userinput></screen>
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<para>After kernel compilation is complete, additional steps are
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required to complete the installation. Some files need to be copied to
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the <filename class="directory">/boot</filename> directory.</para>
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<para>The path to the kernel image may vary depending on the platform being
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used. The filename below can be changed to suit your taste, but the stem of
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the filename should be <emphasis>vmlinuz</emphasis> to be compatible with
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the automatic setup of the boot process described in the next section. The
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following command assumes an x86 architecture:</para>
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<screen><userinput remap="install">cp -v arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen>
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<para><filename>System.map</filename> is a symbol file for the kernel.
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It maps the function entry points of every function in the kernel API,
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as well as the addresses of the kernel data structures for the running
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kernel. It is used as a resource when investigating kernel problems.
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Issue the following command to install the map file:</para>
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<screen><userinput remap="install">cp -v System.map /boot/System.map-&linux-version;</userinput></screen>
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<para>The kernel configuration file <filename>.config</filename>
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produced by the <command>make menuconfig</command> step
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above contains all the configuration selections for the kernel
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that was just compiled. It is a good idea to keep this file for future
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reference:</para>
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<screen><userinput remap="install">cp -v .config /boot/config-&linux-version;</userinput></screen>
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<para>Install the documentation for the Linux kernel:</para>
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<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version;
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cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen>
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<para>It is important to note that the files in the kernel source
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directory are not owned by <emphasis>root</emphasis>. Whenever a
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package is unpacked as user <emphasis>root</emphasis> (like we did
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inside chroot), the files have the user and group IDs of whatever
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they were on the packager's computer. This is usually not a problem
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for any other package to be installed because the source tree is
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removed after the installation. However, the Linux source tree is
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often retained for a long time. Because of this, there is a chance
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that whatever user ID the packager used will be assigned to somebody
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on the machine. That person would then have write access to the kernel
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source.</para>
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<para>If the kernel source tree is going to be retained, run
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<command>chown -R 0:0</command> on the <filename
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class="directory">linux-&linux-version;</filename> directory to ensure
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all files are owned by user <emphasis>root</emphasis>.</para>
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<warning>
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<para>Some kernel documentation recommends creating a symlink from
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<filename class="symlink">/usr/src/linux</filename> pointing to the kernel
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source directory. This is specific to kernels prior to the 2.6 series and
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<emphasis>must not</emphasis> be created on an LFS system as it can cause
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problems for packages you may wish to build once your base LFS system is
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complete.</para>
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</warning>
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<warning>
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<para>The headers in the system's
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<filename class="directory">include</filename> directory should
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<emphasis>always</emphasis> be the ones against which Glibc was compiled,
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that is, the sanitised headers from this Linux kernel tarball.
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Therefore, they should <emphasis>never</emphasis> be replaced by either
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the raw kernel headers or any other kernel sanitized headers.</para>
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</warning>
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</sect2>
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<sect2 id="conf-modprobe" role="configuration">
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<title>Configuring Linux Module Load Order</title>
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<indexterm zone="conf-modprobe">
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<primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary>
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</indexterm>
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<para>The <filename>/etc/modprobe.d/usb.conf</filename> file needs to be
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created so that if the USB drivers (ehci_hcd, ohci_hcd and uhci_hcd) have
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been built as modules, they will be loaded in the correct order; ehci_hcd
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needs to be loaded prior to ohci_hcd and uhci_hcd in order to avoid a
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warning being output at boot time.</para>
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<para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running
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the following:</para>
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<screen><userinput>install -v -m755 -d /etc/modprobe.d
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cat > /etc/modprobe.d/usb.conf << "EOF"
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<literal># Begin /etc/modprobe.d/usb.conf
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install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true
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install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true
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# End /etc/modprobe.d/usb.conf</literal>
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EOF</userinput></screen>
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</sect2>
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<sect2 id="contents-kernel" role="content">
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<title>Contents of Linux</title>
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<segmentedlist>
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<segtitle>Installed files</segtitle>
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<segtitle>Installed directories</segtitle>
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<seglistitem>
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<seg>config-&linux-version;,
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vmlinux-&linux-version;-lfs-&version;-&linux-version;, and
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System.map-&linux-version;</seg>
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<seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg>
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</seglistitem>
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</segmentedlist>
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<variablelist>
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<bridgehead renderas="sect3">Short Descriptions</bridgehead>
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<?dbfo list-presentation="list"?>
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<?dbhtml list-presentation="table"?>
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<varlistentry id="config">
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<term><filename>config-&linux-version;</filename></term>
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<listitem>
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<para>Contains all the configuration selections for the kernel</para>
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<indexterm zone="ch-bootable-kernel config">
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<primary sortas="e-/boot/config">/boot/config-&linux-version;</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="lfskernel">
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<term><filename>vmlinux-&linux-version;-lfs-&version;</filename></term>
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<listitem>
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<para>The engine of the Linux system. When turning on the computer,
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the kernel is the first part of the operating system that gets loaded.
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It detects and initializes all components of the computer's hardware,
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then makes these components available as a tree of files to the
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software and turns a single CPU into a multitasking machine capable
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of running scores of programs seemingly at the same time</para>
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<indexterm zone="ch-bootable-kernel lfskernel">
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<primary sortas="b-lfskernel">lfskernel-&linux-version;</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="System.map">
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<term><filename>System.map-&linux-version;</filename></term>
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<listitem>
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<para>A list of addresses and symbols; it maps the entry points and
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addresses of all the functions and data structures in the
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kernel</para>
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<indexterm zone="ch-bootable-kernel System.map">
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<primary sortas="e-/boot/System.map">/boot/System.map-&linux-version;</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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</sect1>
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