diff options
Diffstat (limited to 'chapter10/kernel.xml')
| -rw-r--r-- | chapter10/kernel.xml | 424 |
1 files changed, 424 insertions, 0 deletions
diff --git a/chapter10/kernel.xml b/chapter10/kernel.xml new file mode 100644 index 000000000..a724bd078 --- /dev/null +++ b/chapter10/kernel.xml @@ -0,0 +1,424 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ + <!ENTITY % general-entities SYSTEM "../general.ent"> + %general-entities; +]> + +<sect1 id="ch-bootable-kernel" role="wrap"> + <?dbhtml filename="kernel.html"?> + + <sect1info condition="script"> + <productname>kernel</productname> + <productnumber>&linux-version;</productnumber> + <address>&linux-url;</address> + </sect1info> + + <title>Linux-&linux-version;</title> + + <indexterm zone="ch-bootable-kernel"> + <primary sortas="a-Linux">Linux</primary> + </indexterm> + + <sect2 role="package"> + <title/> + + <para>The Linux package contains the Linux kernel.</para> + + <segmentedlist> + <segtitle>&buildtime;</segtitle> + <segtitle>&diskspace;</segtitle> + + <seglistitem> + <seg>&linux-knl-sbu;</seg> + <seg>&linux-knl-du;</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 alternative methods to the way this book + configures the kernel.</para> + + <para>Prepare for compilation by running the following command:</para> + +<screen><userinput remap="pre">make mrproper</userinput></screen> + + <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> + + <!-- Support for compiling a keymap into the kernel is deliberately removed --> + + <para>Configure the kernel via a menu-driven interface. For general + information on kernel configuration see <ulink + url="&hints-root;kernel-configuration.txt"/>. BLFS has some information + regarding particular kernel configuration requirements of packages outside + of LFS at <ulink + url="&blfs-book;longindex.html#kernel-config-index"/>. Additional + information about configuring and building the kernel can be found at + <ulink url="http://www.kroah.com/lkn/"/> </para> + + <note> + + <para>A good starting place for setting up the kernel configuration is to + run <command>make defconfig</command>. This will set the base + configuration to a good state that takes your current system architecture + into account.</para> + + <para>Be sure to enable/disable/set the following features or the system might + not work correctly or boot at all:</para> + + <screen role="nodump" revision="sysv"> +Device Drivers ---> + Generic Driver Options ---> + [ ] Support for uevent helper [CONFIG_UEVENT_HELPER] + [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS] + +Kernel hacking ---> + Choose kernel unwinder (Frame pointer unwinder) ---> [CONFIG_UNWINDER_FRAME_POINTER]</screen> + + <screen role="nodump" revision="systemd"> +General setup --> + [*] Control Group support [CONFIG_CGROUPS] + [ ] Enable deprecated sysfs features to support old userspace tools [CONFIG_SYSFS_DEPRECATED] + [*] Configure standard kernel features (expert users) [CONFIG_EXPERT] ---> + [*] open by fhandle syscalls [CONFIG_FHANDLE] + [ ] Auditing support [CONFIG_AUDIT] +Processor type and features ---> + [*] Enable seccomp to safely compute untrusted bytecode [CONFIG_SECCOMP] +Firmware Drivers ---> + [*] Export DMI identification via sysfs to userspace [CONFIG_DMIID] +Networking support ---> + Networking options ---> + <*> The IPv6 protocol [CONFIG_IPV6] +Device Drivers ---> + Generic Driver Options ---> + [ ] Support for uevent helper [CONFIG_UEVENT_HELPER] + [*] Maintain a devtmpfs filesystem to mount at /dev [CONFIG_DEVTMPFS] + Firmware Loader ---> + [ ] Enable the firmware sysfs fallback mechanism [CONFIG_FW_LOADER_USER_HELPER] +File systems ---> + [*] Inotify support for userspace [CONFIG_INOTIFY_USER] + <*> Kernel automounter support (supports v3, v4, and v5) [CONFIG_AUTOFS_FS] + Pseudo filesystems ---> + [*] Tmpfs POSIX Access Control Lists [CONFIG_TMPFS_POSIX_ACL] + [*] Tmpfs extended attributes [CONFIG_TMPFS_XATTR]</screen> + </note> + + <note revision="systemd"> + <para>While "The IPv6 Protocol" is not strictly + required, it is highly recommended by the systemd developers.</para> + </note> + + <para revision="sysv">There are several other options that may be desired + depending on the requirements for the system. For a list of options needed + for BLFS packages, see the <ulink + url="&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index">BLFS + Index of Kernel Settings</ulink> + (&lfs-root;blfs/view/&short-version;/longindex.html#kernel-config-index).</para> + + <note> + <para>If your host hardware is using UEFI, then the 'make defconfig' + above should automatically add in some EFI-related kernel options.</para> + + <para>In order to allow your LFS kernel to be booted from within your + host's UEFI boot environment, your kernel must have this option + selected:</para> + +<screen role="nodump">Processor type and features ---> + [*] EFI stub support [CONFIG_EFI_STUB]</screen> + + <para>A fuller description of managing UEFI environments from within LFS + is covered by the lfs-uefi.txt hint at + <ulink + url="&hints-root;lfs-uefi.txt"/>. + </para> + </note> + + <note arch="ml_32,ml_x32,ml_all"> + <para> + Running a multilib system means also that the kernel has to be + configured proper. It is required that the kernel is able to + identify and start binaries compiled for different architectures + than the default. Setup the required parameter in the kernel + config: + </para> +<screen>Binary Emulations ---> + [*] IA32 Emulation + <M> IA32 a.out support + [*] x32 ABI for 64-bit mode +</screen> + <para>Make sure that the option + 'IA32 Emulation' is set if you built support for the 32bit ABI. + If you selected the x32 ABI or built support for both, also select + 'x32 ABI for 64-bit mode'. The option 'IA32 a.out support' is + optional. + </para> + </note> + + <variablelist> + <title>The rationale for the above configuration items:</title> + + <varlistentry> + <term><parameter>Support for uevent helper</parameter></term> + <listitem> + <para>Having this option set may interfere with device + management when using Udev/Eudev. </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><parameter>Maintain a devtmpfs</parameter></term> + <listitem> + <para>This will create automated device nodes which are populated by the + kernel, even without Udev running. Udev then runs on top of this, + managing permissions and adding symlinks. This configuration + item is required for all users of Udev/Eudev.</para> + </listitem> + </varlistentry> + + </variablelist> + +<screen role="nodump"><userinput>make menuconfig</userinput></screen> + + <variablelist> + <title>The meaning of optional make environment variables:</title> + + <varlistentry> + <term><parameter>LANG=<host_LANG_value> LC_ALL=</parameter></term> + <listitem> + <para>This establishes the locale setting to the one used on the + host. This may be needed for a proper menuconfig ncurses interface + line drawing on a UTF-8 linux text console.</para> + + <para>If used, be sure to replace + <replaceable><host_LANG_value></replaceable> by the value of + the <envar>$LANG</envar> variable from your host. You can + alternatively use instead the host's value of <envar>$LC_ALL</envar> + or <envar>$LC_CTYPE</envar>.</para> + </listitem> + </varlistentry> + + </variablelist> + + <para>Alternatively, <command>make oldconfig</command> may be more + appropriate in some situations. See the <filename>README</filename> + file for more information.</para> + + <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>Compile the kernel image and modules:</para> + +<screen><userinput remap="make">make</userinput></screen> + + <para>If using kernel modules, module configuration in <filename + class="directory">/etc/modprobe.d</filename> may be required. + Information pertaining to modules and kernel configuration is + located in <xref linkend="ch-config-udev"/> and in the kernel + documentation in the <filename + class="directory">linux-&linux-version;/Documentation</filename> directory. + Also, <filename>modprobe.d(5)</filename> may be of interest.</para> + + <para>Unless module support has been disabled in the kernel configuration, + install the modules with:</para> + +<screen><userinput remap="install">make modules_install</userinput></screen> + + <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> + + <caution> + <para>If the host system has a separate /boot partition, the files copied + below should go there. The easiest way to do that is to bind /boot on the + host (outside chroot) to /mnt/lfs/boot before proceeding. As the root + user in the <emphasis>host system</emphasis>:</para> + +<screen role="nodump"><userinput>mount --bind /boot /mnt/lfs/boot</userinput></screen> + </caution> + + <para>The path to the kernel image may vary depending on the platform being + used. The filename below can be changed to suit your taste, but the stem of + the filename should be <emphasis>vmlinuz</emphasis> to be compatible with + the automatic setup of the boot process described in the next section. The + following command assumes an x86 architecture:</para> + +<screen revision="sysv"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&version;</userinput></screen> + +<screen revision="systemd"><userinput remap="install">cp -iv arch/x86/boot/bzImage /boot/vmlinuz-&linux-version;-lfs-&versiond;</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. It is used as a resource when investigating kernel problems. + Issue the following command to install the map file:</para> + +<screen><userinput remap="install">cp -iv 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 remap="install">cp -iv .config /boot/config-&linux-version;</userinput></screen> + + <para>Install the documentation for the Linux kernel:</para> + +<screen><userinput remap="install">install -d /usr/share/doc/linux-&linux-version; +cp -r Documentation/* /usr/share/doc/linux-&linux-version;</userinput></screen> + + <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> + + <note> + <para>In many cases, the configuration of the kernel will need to be + updated for packages that will be installed later in BLFS. Unlike + other packages, it is not necessary to remove the kernel source tree + after the newly built kernel is installed.</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> + </note> + + <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> + + <warning> + <para>The headers in the system's <filename + class="directory">include</filename> directory (<filename + class="directory">/usr/include</filename>) should + <emphasis>always</emphasis> be the ones against which Glibc was compiled, + that is, the sanitised headers installed in <xref + linkend="ch-tools-linux-headers"/>. Therefore, they should + <emphasis>never</emphasis> be replaced by either the raw kernel headers + or any other kernel sanitized headers.</para> + </warning> + + </sect2> + + <sect2 id="conf-modprobe" role="configuration"> + <title>Configuring Linux Module Load Order</title> + + <indexterm zone="conf-modprobe"> + <primary sortas="e-/etc/modprobe.d/usb.conf">/etc/modprobe.d/usb.conf</primary> + </indexterm> + + <para>Most of the time Linux modules are loaded automatically, but + sometimes it needs some specific direction. The program that loads + modules, <command>modprobe</command> or <command>insmod</command>, uses + <filename>/etc/modprobe.d/usb.conf</filename> for this purpose. This file + needs to be created so that if the USB drivers (ehci_hcd, ohci_hcd and + uhci_hcd) have been built as modules, they will be loaded in the correct + order; ehci_hcd needs to be loaded prior to ohci_hcd and uhci_hcd in order + to avoid a warning being output at boot time.</para> + + <para>Create a new file <filename>/etc/modprobe.d/usb.conf</filename> by running + the following:</para> + +<screen><userinput>install -v -m755 -d /etc/modprobe.d +cat > /etc/modprobe.d/usb.conf << "EOF" +<literal># Begin /etc/modprobe.d/usb.conf + +install ohci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i ohci_hcd ; true +install uhci_hcd /sbin/modprobe ehci_hcd ; /sbin/modprobe -i uhci_hcd ; true + +# End /etc/modprobe.d/usb.conf</literal> +EOF</userinput></screen> + + </sect2> + + <sect2 id="contents-kernel" role="content"> + <title>Contents of Linux</title> + + <segmentedlist> + <segtitle>Installed files</segtitle> + <segtitle>Installed directories</segtitle> + + <seglistitem> + <seg>config-&linux-version;, + <phrase revision="sysv">vmlinuz-&linux-version;-lfs-&version;,</phrase> + <phrase revision="systemd">vmlinuz-&linux-version;-lfs-&versiond;,</phrase> + and System.map-&linux-version;</seg> + <seg>/lib/modules, /usr/share/doc/linux-&linux-version;</seg> + </seglistitem> + </segmentedlist> + + <variablelist> + <bridgehead renderas="sect3">Short Descriptions</bridgehead> + <?dbfo list-presentation="list"?> + <?dbhtml list-presentation="table"?> + + <varlistentry id="config"> + <term><filename>config-&linux-version;</filename></term> + <listitem> + <para>Contains all the configuration selections for the kernel</para> + <indexterm zone="ch-bootable-kernel config"> + <primary sortas="e-/boot/config">/boot/config-&linux-version;</primary> + </indexterm> + </listitem> + </varlistentry> + + <varlistentry id="lfskernel"> + <term revision="sysv"><filename>vmlinuz-&linux-version;-lfs-&version;</filename></term> + <term revision="systemd"><filename>vmlinuz-&linux-version;-lfs-&versiond;</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 lfskernel"> + <primary sortas="b-lfskernel">lfskernel-&linux-version;</primary> + </indexterm> + </listitem> + </varlistentry> + + <varlistentry id="System.map"> + <term><filename>System.map-&linux-version;</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-&linux-version;</primary> + </indexterm> + </listitem> + </varlistentry> + + </variablelist> + + </sect2> + +</sect1> |