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Diffstat (limited to 'chapter08/kernel.xml')
| -rw-r--r-- | chapter08/kernel.xml | 197 |
1 files changed, 179 insertions, 18 deletions
diff --git a/chapter08/kernel.xml b/chapter08/kernel.xml index 9fe3bc889..4b775a3d9 100644 --- a/chapter08/kernel.xml +++ b/chapter08/kernel.xml @@ -3,26 +3,37 @@ <!ENTITY % general-entities SYSTEM "../general.ent"> %general-entities; ]> -<sect1 id="ch-bootable-kernel" xreflabel="Linux" role="wrap"> +<sect1 id="ch-bootable-kernel" role="wrap"> <title>Linux-&linux-version;</title> <?dbhtml filename="kernel.html"?> <indexterm zone="ch-bootable-kernel"><primary sortas="a-Linux">Linux</primary></indexterm> <sect2 role="package"><title/> +<para>The Linux package contains the kernel and the header files.</para> <segmentedlist> <segtitle>&buildtime;</segtitle> <segtitle>&diskspace;</segtitle> -<seglistitem><seg>All default options: 4.20 SBU</seg> -<seg>All default options: 181 MB</seg></seglistitem> +<seglistitem><seg>4.20 SBU</seg> +<seg>181 MB</seg></seglistitem> </segmentedlist> +<segmentedlist> +<segtitle>Linux installation depends on</segtitle> +<seglistitem><seg>Bash, Binutils, Coreutils, Findutils, +GCC, Glibc, Grep, Gzip, Make, Modutils, Perl, and Sed</seg></seglistitem> +</segmentedlist> </sect2> <sect2 role="installation"> <title>Installation of the kernel</title> +<para>Building the kernel involves a few steps—configuration, +compilation, and installation. Read the <filename>README</filename> +file in the kernel source tree for alternate methods to the way this +book configures the kernel.</para> + <para>Kernel version 2.6.10 has a security vulnerability that will allow user processes to gain root privledges upon loading of a kernel module. See: <ulink url="http://www.uwsg.iu.edu/hypermail/linux/kernel/0412.3/0679.html"/> for more information. The following patch fixes this problem:</para> @@ -33,50 +44,200 @@ processes to gain root privledges upon loading of a kernel module. See: <screen><userinput>make mrproper</userinput></screen> -<!--NEW: the sed command has been removed--> +<para>This ensures that the kernel tree is absolutely clean. The +kernel team recommends that this command be issued prior to each +kernel compilation. Do not rely on the source tree being clean after +un-tarring.</para> -<para>If, in <xref linkend="ch-scripts-console"/>, you decided you want -to compile the keymap into the kernel, issue the command below:</para> +<para>If, in <xref linkend="ch-scripts-console" role=","/> it was decided to +compile the keymap into the kernel, issue the command below:</para> <screen><userinput>loadkeys -m /usr/share/kbd/keymaps/<replaceable>[path to keymap]</replaceable> > \ drivers/char/defkeymap.c</userinput></screen> -<para>Configure the kernel via a menu-driven interface. BLFS has some -information regarding particular kernel configuration requirements of -packages outside of LFS at -<ulink url="&blfs-root;view/svn/longindex.html#kernel-config-index"/>.</para> +<para>For example, if using a Dutch keyboard, use +<phrase +condition="html"><filename>/usr/share/kbd/keymaps/i386/qwerty/nl.map.gz</filename></phrase><phrase +condition="pdf"><filename>/usr/share/kbd/keymaps/i386/ +qwerty/nl.map.gz</filename></phrase>.</para> + +<para>Configure the kernel via a menu-driven interface:</para> <screen><userinput>make menuconfig</userinput></screen> +<para>Alternatively, <command>make oldconfig</command> may be more appropriate in some +situations. See the <filename>README</filename> file for more +information.</para> + +<note><para>When configuring the kernel, be sure to enable the +<quote>Support for hot-pluggable devices</quote> option under the +<quote>General Setup</quote> menu. This enables hotplug events that +are used by <command>udev</command> to populate the <filename +class="directory">/dev</filename> directory with device +nodes.</para></note> + +<para>If desired, skip kernel configuration by copying the kernel +config file, <filename>.config</filename>, from the host system +(assuming it is available) to the unpacked <filename +class="directory">linux-&linux-version;</filename> directory. However, +we do not recommend this option. It is often better to explore all the +configuration menus and create the kernel configuration from +scratch.</para> + +<para>For POSIX-shared memory support, ensure that the kernel config +option <quote>Virtual memory file system support</quote> is enabled. +It resides within the <quote>File systems</quote> menu and is normally +enabled by default.</para> + +<para>LFS bootscripts make the assumption that either both +<quote>Support for Host-side USB</quote> and <quote>USB device +filesystem</quote> have been compiled directly into the kernel, or +that neither is compiled at all. Bootscripts will not work properly +if it is a module (usbcore.ko).</para> + +<note><para>NPTL requires the kernel to be compiled with GCC 3.x, in +this case &gcc-version;. Compiling with 2.95.x is known to cause failures in +the glibc test suite, so it is not recommended to compile the kernel +with gcc 2.95.x.</para></note> + <para>Compile the kernel image and modules:</para> <screen><userinput>make</userinput></screen> -<para>Install the modules, if your kernel configuration uses them:</para> +<para>If using kernel modules, an +<filename>/etc/modprobe.conf</filename> file may be needed. +Information pertaining to modules and kernel configuration is +located in the kernel documentation in the <filename +class="directory">linux-&linux-version;/Documentation</filename> +directory. The <emphasis>modprobe.conf</emphasis> man page may also be +of interest.</para> + +<para>Be very careful when reading other documentation because it +usually applies to 2.4.x kernels only. As far as we know, kernel +configuration issues specific to Hotplug and Udev are not documented. +The problem is that Udev will create a device node only if Hotplug or +a user-written script inserts the corresponding module into the +kernel, and not all modules are detectable by Hotplug. Note that +statements like the one below in the +<filename>/etc/modprobe.conf</filename> file do not work with +Udev:</para> + +<para><screen>alias char-major-XXX some-module</screen></para> + +<para>Because of the complications with Hotplug, Udev, and modules, we +strongly recommend starting with a completely non-modular kernel +configuration, especially if this is the first time using Udev.</para> + +<para>Install the modules, if the kernel configuration uses them:</para> <screen><userinput>make modules_install</userinput></screen> -<para>The path to the kernel image may vary depending on the platform you're -using. Issue the following command to install the kernel:</para> +<para>If there are many modules and very little space, consider +stripping and compressing the modules. For most users, such +compression is not worth the time, but if the system is pressed for +space, see <ulink +url="http://www.linux-mips.org/archives/linux-mips/2002-04/msg00031.html"/>.</para> + +<para>After kernel compilation is complete, additional steps are +required to complete the installation. Some files need to be copied to +the <filename class="directory">/boot</filename> directory.</para> + +<para>The path to the kernel image may vary depending on the platform +being used. Issue the following command to install the kernel:</para> <screen><userinput>cp arch/i386/boot/bzImage /boot/lfskernel-&linux-version;</userinput></screen> +<para><filename>System.map</filename> is a symbol file for the kernel. +It maps the function entry points of every function in the kernel API, +as well as the addresses of the kernel data structures for the running +kernel. Issue the following command to install the map file:</para> + <screen><userinput>cp System.map /boot/System.map-&linux-version;</userinput></screen> +<para>The kernel configuration file <filename>.config</filename> +produced by the <command>make menuconfig</command> step +above contains all the configuration selections for the kernel +that was just compiled. It is a good idea to keep this file for future +reference:</para> + <screen><userinput>cp .config /boot/config-&linux-version;</userinput></screen> -<para>If you are going to keep the kernel source tree around, you may want to -run <command>chown -R 0:0</command> on the -<filename class="directory">linux-&linux-version;</filename> directory to ensure all files are -owned by user <emphasis>root</emphasis>.</para> +<para>It is important to note that the files in the kernel source +directory are not owned by <emphasis>root</emphasis>. Whenever a +package is unpacked as user <emphasis>root</emphasis> (like we did +inside chroot), the files have the user and group IDs of whatever +they were on the packager's computer. This is usually not a problem +for any other package to be installed because the source tree is +removed after the installation. However, the Linux source tree is +often retained for a long time. Because of this, there is a chance +that whatever user ID the packager used will be assigned to somebody +on the machine. That person would then have write access to the kernel +source.</para> + +<para>If the kernel source tree is going to be retained, run +<command>chown -R 0:0</command> on the <filename +class="directory">linux-&linux-version;</filename> directory to ensure +all files are owned by user <emphasis>root</emphasis>.</para> + +<warning><para>Some kernel documentation recommends creating a symlink from +<filename class="symlink">/usr/src/linux</filename> pointing to the kernel +source directory. This is specific to kernels prior to the 2.6 series and +<emphasis>must not</emphasis> be created on an LFS system as it can cause +problems for packages you may wish to build once your base LFS system is +complete.</para></warning> </sect2> <sect2 id="contents-kernel" role="content"><title>Contents of Linux</title> -<para>See testing</para> +<segmentedlist> +<segtitle>Installed files</segtitle> +<seglistitem><seg>kernel, kernel headers, +and System.map</seg></seglistitem> +</segmentedlist> + +<variablelist><bridgehead renderas="sect3">Short Descriptions</bridgehead> +<?dbfo list-presentation="list"?> + +<varlistentry id="kernel"> +<term><filename>kernel</filename></term> +<listitem> +<para>The engine of the Linux system. When turning on the computer, +the kernel is the first part of the operating system that gets loaded. +It detects and initializes all components of the computer's hardware, +then makes these components available as a tree of files to the +software and turns a single CPU into a multitasking machine capable +of running scores of programs seemingly at the same time.</para> +<indexterm zone="ch-bootable-kernel kernel"><primary sortas="b-kernel">kernel</primary></indexterm> +</listitem> +</varlistentry> + +<varlistentry id="kernel-headers"> +<term><filename>kernel headers</filename></term> +<listitem> +<para>Defines the interface to the services that the kernel provides. +The headers in the system's <filename +class="directory">include</filename> directory should +<emphasis>always</emphasis> be the ones against which Glibc was +compiled and therefore, should <emphasis>not</emphasis> be replaced +when upgrading the kernel.</para> +<indexterm zone="ch-bootable-kernel kernel-headers"><primary sortas="e-kernel-headers">kernel headers</primary></indexterm> +</listitem> +</varlistentry> + +<varlistentry id="System.map"> +<term><filename>System.map</filename></term> +<listitem> +<para>A list of addresses and symbols; it maps the entry points and +addresses of all the functions and data structures in the +kernel</para> +<indexterm zone="ch-bootable-kernel System.map"><primary sortas="e-/boot/System.map">/boot/System.map</primary></indexterm> +</listitem> +</varlistentry> +</variablelist> </sect2> </sect1> + |