LDP/LDP/howto/docbook/Kernel-Build-HOWTO/Kernel-Build-HOWTO.sgml

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.1//EN">

<book lang="en">
	<bookinfo>
  		<title>Kernel Rebuild Guide</title>
		<pubdate>2003-11-10</pubdate>
		<authorgroup>
			<author>
				<firstname>Kwan</firstname>
				<surname>Lowe</surname>
				<affiliation>
					<orgname>Digital Hermit</orgname>
					<address><email>kwan@digitalhermit.com</email></address>
				</affiliation>
			</author>
		</authorgroup>

		<editor>
			<firstname>Doug</firstname>
			<surname>Jensen</surname>
			<contrib>Language and technical review</contrib>
		</editor>

		<editor>
			<firstname>Michael</firstname>
			<surname>Kerrisk</surname>
			<contrib>Language review</contrib>
		</editor>

  		<revhistory>
			<revision>
				<revnumber>1.0</revnumber>
				<date>2004-04-19</date>
				<authorinitials>kll</authorinitials>
				<revremark>An initial revision to gather feedback.</revremark>
			</revision>
		</revhistory>

		<abstract>
			<para>
				This is a guide to building the 2.4.x and 2.6.0 Linux kernels.
				It is intended for moderately experienced Linux users who are 
				interested in learning more about the kernel and the rebuild
				process.
			</para>
		</abstract>

		<keywordset>
			<keyword>kernel</keyword>
			<keyword>rebuild</keyword>
		</keywordset>

	</bookinfo>

	<dedication id="dedication">
		<title>Dedication</title>
		<para>To penguin lovers everywhere...</para>
	</dedication> <!-- dedication -->


<chapter id="intro">
	<title>Introduction</title>


	<section id="why-rebuild">
		<title>Why Rebuild?</title>
		<para>
			Why rebuild the kernel? The main reason was once to optimize the
			kernel to your environment (hardware and usage patterns). With
			modern hardware there is rarely a need to recompile unless there
			is a particular feature of a new kernel that you must have. The
			performance gains are probably not noticeable unless specific
			benchmarks are being run. 
		</para>
		<para>
			This said, the newest Linux kernel (2.6.0test9 as of this writing)
			has noticeable improvements for the typical desktop user as a result
			of the improved scheduling system in the new kernel. Even for older
			kernels, rebuilding is often necessary for low memory situations,
			esoteric hardware, and in cases where every ounce of performance must
			be extracted.
		</para> 
		<para>
			This guide covers the steps necessary to build both the 2.4.x and 2.6.x
			series of kernels. Because the process is quite different from one version
			to the next, the versions are separated by chapters. 
		</para>

	</section> <!-- why-rebuild -->


	<section id="section-intro">
		<title>What is the kernel?</title>
		<para>
			The Linux kernel is often likened to the conductor in an orchestra. Among 
			other things, it makes sure that all other processes in the system work
			together coherently. Though it is only a small part of the operating system,
			the kernel has the most important job of keeping everything else synchronized.
		</para>
	</section> <!-- section-intro -->

	<!-- You'll want to use something more descriptive than section2 for 
		the section name. The idea is that you can re-arrange sections
		and refer to them by keyword rather than number. -->
</chapter> <!-- Intro -->

<chapter id="preparation">
	<title>Preparation</title>
	<section id="hardware-requirements">
		<title>Hardware Requirements</title>

		<para>
			Hardware requirements can differ greatly between kernel versions, and indeed,
			within versions depending upon the configuration. Though the Linux 2.4.x kernel
			can boot with as little as 8M of RAM, a more realistic number is about 64M. 
			As of this writing, the published minimum hardware required for the typical distribution
			is about 128M RAM, 2G of hard drive space, and 200MhZ Pentium or equivalent CPU.
			To actually build the kernel, however, requires a little extra hardware. The 
			kernel sources themselves will occupy anywhere from 40M to 80M of filesystem space. 
			To build them requires a minimum of 400M of drive space for all the interim files.
			The actual kernel and included modules will require anywhere from 4M for an almost 
			useless, bare minimum kernel to about 40M fully loaded.
			<footnote>
				<para>
					I have successfully installed a serviceable machine on an original Pentium 100, 
					64M RAM, and 1.2G of drive space. A full build of the 2.6.0test9 kernel took 
					approximately 4 hours to complete.
				</para>
			</footnote>
			Luckily, the kernel does not need to be built on the same machine on which it
			will be deployed. This means that you can compile and package your kernel on 
			a more robust machine and then install on the minimal system.
		</para>
	</section>

	<section id="software-requirements">
		<title>Software Requirements</title>
		<para>
			The minimum software versions for a kernel build are found in the 
			<filename>./Documentation/Changes</filename>
			file of the installed sources. They are as follows:

		2.4.x series
		<programlisting>
		o  Gnu C                  2.91.66     # gcc --version
		o  Gnu make               3.77        # make --version
		o  binutils               2.9.1.0.25  # ld -v
		o  util-linux             2.10o       # fdformat --version
		o  modutils               2.4.2       # insmod -V
		o  e2fsprogs              1.19        # tune2fs
		o  reiserfsprogs          3.x.0b      # reiserfsck 2>&1|grep reiserfsprogs
		o  pcmcia-cs              3.1.21      # cardmgr -V
		o  PPP                    2.4.0       # pppd --version
		o  isdn4k-utils           3.1pre1     # isdnctrl 2>&1|grep version

		</programlisting>

		2.6.x series
		<programlisting>
		o  Gnu C                  2.95.3       # gcc --version
		o  Gnu make               3.78         # make --version
		o  binutils               2.12         # ld -v
		o  util-linux             2.10o        # fdformat --version
		o  module-init-tools      0.9.10       # depmod -V
		o  e2fsprogs              1.29         # tune2fs 
		o  jfsutils               1.1.3        # fsck.jfs -V
		o  reiserfsprogs          3.6.3        # reiserfsck -V 2>&1|grep reiserfsprogs
		o  xfsprogs               2.1.0        # xfs_db -V
		o  pcmcia-cs              3.1.21       # cardmgr -V
		o  quota-tools            3.09         # quota -V
		o  PPP                    2.4.0        # pppd --version
		o  isdn4k-utils           3.1pre1      # isdnctrl 2>&1|grep version
		o  nfs-utils              1.0.5        # showmount --version
		o  procps                 3.1.13       # ps --version
		o  oprofile               0.5.3        # oprofiled --version
		</programlisting>
		
		A common sticking point on distributions transitioning between
		2.4.x and 2.6.x kernels is the <filename>module-init-tools</filename>
		package which must be updated to work with the 2.6.x kernel. Also,
		be aware that the underlying version of glibc, the GNU libc
		package, is implied. If you are upgrading from particularly old
		distributions then you will likely need to upgrade glibc itself.

		<footnote>
			<para>
			On an RPM based system you can query a minimal version with a
			command such as:
			<screen>
			<prompt>$ </prompt><command>rpm -q --requires gcc|grep glibc</command>
			</screen>
			</para>
		</footnote>
		
		</para>
	</section>

	<section id="determine-hardware">
		<title>Determine Current Hardware</title>
		<para>
			Once you have determined that your hardware and software meet the minimum
			requirements for the kernel build, we will need to collect more detailed 
			information about the system. This is needed during the configuration process
			when we decide which hardware will be supported under our new kernel. Among
			the information we will gather include: Processor, Drive type and Controller 
			(SCSI, IDE), Ethernet devices, Graphics and Sound Cards, USB HUB.
		</para>

		<para>
			We start by running the <filename>/sbin/lspci</filename> utility to print
			information about our hardware:

		<screen>
			<prompt>$ </prompt><command>/sbin/lspci</command>
		</screen>

		<programlisting>
		00:00.0 Host bridge: Silicon Integrated Systems [SiS] 735 Host (rev 01)
		00:01.0 PCI bridge: Silicon Integrated Systems [SiS] 5591/5592 AGP
		00:02.0 ISA bridge: Silicon Integrated Systems [SiS] 85C503/5513
		00:02.2 USB Controller: Silicon Integrated Systems [SiS] 7001 (rev 07)
		00:02.3 USB Controller: Silicon Integrated Systems [SiS] 7001 (rev 07)
		00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE] (rev d0)
		00:02.7 Multimedia audio controller: SiS7012 PCI Audio Accelerator (rev a0)
		00:03.0 Ethernet controller: [SiS] SiS900 10/100 Ethernet (rev 90)
		01:00.0 VGA compatible controller: ATI Technologies Inc Rage 128 RF/SG AGP
		</programlisting>

		Next, we must determine our processor type if not known. Some Linux systems 
		contain a <filename>/proc</filename> filesystem that allows a user to view 
		raw information about the system. If <filename>/proc</filename> exists you
		can issue the following command to get CPU information:

		<screen>
			<prompt>$ </prompt><command>cat /proc/cpuinfo</command>
		</screen>
		<programlisting>

		processor       : 0
		vendor_id       : AuthenticAMD
		cpu family      : 6
		model           : 6
		model name      : AMD Athlon(tm) XP 1800+
		stepping        : 2
		cpu MHz         : 1526.870
		cache size      : 256 KB
		fdiv_bug        : no
		hlt_bug         : no
		f00f_bug        : no
		coma_bug        : no
		fpu             : yes
		fpu_exception   : yes
		cpuid level     : 1
		wp              : yes
		flags           : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge 
		bogomips        : 3047.42
		</programlisting>
		</para>
	</section>

	<section id="download">
		<title>Acquiring the Sources</title>

		<para>
		There are many ways to acquire the Linux kernel sources. If you are using a
		packaged distribution then most likely the distributor will bundle a kernel
		source package. These are installable via the package installation method,
		whether RPM, apt, YAST, portage, etc.. If you decide to go this route, please 
		consult your distributions documentation for specifics. 
		</para>
		<para>
		The other option is to use the <quote>pristine</quote> sources, either the
		<quote>official</quote> sources from Linus Torvalds himself, or one of the
		regularly maintained trees from people such as Alan Cox, Robert Love, et al..
		These sources are often on the bleeding-edge of kernel development, full of
		new features and untested code. 
		</para>
		<para>
		Untested code? This is a feature of the distributed development model of Linux
		and Open Source (??) in general. The traditional model of a software release is
		somewhat antithetical to this model, as new code must be released to allow 
		all developers to test and improve the code. However, because Linux is used in 
		production environments throughout world it is necessary to separate the unstable
		development tree from the tested, stable tree. This is done through the version
		number of the kernel. There are three main numbers associated with the kernel --
		the Major, Minor, and PatchLevel fields. The Major number rarely changes, and
		then only when/if the entire architecture is revamped. The Minor number changes
		more frequently, perhaps once every couple years. Kernels with an odd Minor number 
		are considered unstable, testing branches. Even Minor numbers are generally rock
		solid. The PatchLevel is updated frequently, sometimes more than once a week in
		extreme cases. 
		</para>
		<para>
		To recap, you can build either from your distribution's modified kernel sources
		or from the stable or unstable branch of the offical sources. If you are making
		minor modifications to the configuration it is perhaps safest to install your
		distributor's version. These kernels usually include stability and feature 
		patches that may be missing from the stock kernels. For example, some distributors
		will include low-latency or security patches and do the more difficult work of
		integrating these into their system. The downside is that the distributors tend
		to lag the bleeding-edge kernels. If you would like to test the improved 
		responsiveness of the 2.6.0 tree then you will need to build from source.
		</para>
	</section> 


	<section id="download-source">
		<title>Download the Source</title>

		<para>
		Though the latest sources are always available from <ulink url="http://kernel.org">
		<citetitle>http://kernel.org</citetitle></ulink>, to be kind to the Internet, always 
		use one of the mirrors listed at <ulink url="http://kernel.org/mirrors">
		<citetitle>http://kernel.org/mirrors</citetitle></ulink>. In general, geographically
		close mirrors will tend to be fastest. You can either browse the sites with an
		Internet browser or with a dedicated FTP client.
		</para>
		<para>
		You will see several links to <filename>/pub/linux</filename> on
		the mirror site. Select the <filename>kernel</filename> directory,
		then the kernel version that you would like to install. As of
		this writing, 2.4.22 is the latest stable version and 2.6.0 is in
		pre-release state. Once you select a kernel version you will see
		several files.

		<programlisting>
		ChangeLog-2.6.0-test9          25-Oct-2003 14:51    41k  
		LATEST-IS-2.6.0-test9          25-Oct-2003 14:51     0k  
		linux-2.6.0-test9.tar.bz2.sign 25-Oct-2003 15:14     1k  
		linux-2.6.0-test9.tar.gz       25-Oct-2003 15:14  39.7M  
		linux-2.6.0-test9.tar.gz.sign  25-Oct-2003 15:14     1k  
		linux-2.6.0-test9.tar.sign     25-Oct-2003 15:14     1k  
		patch-2.6.0-test9.bz2.sign     25-Oct-2003 15:14     1k  
		patch-2.6.0-test9.gz           25-Oct-2003 15:14   123k  
		patch-2.6.0-test9.gz.sign      25-Oct-2003 15:14     1k  
		patch-2.6.0-test9.sign         25-Oct-2003 15:14     1k  	
		</programlisting>

		The Changelog files detail the differences between versions. The
		linux- files are the compressed sources for the entire Linux kernel.
		Most sites will contain both gzip and bzip packages. The bzip
		packages tend to be about 20% smaller than the GZIP versions, so
		it is usually the best option since all modern Linux distributions contain
		BZIP utilities. Finally, the patch files are a list of differences
		between versions of the kernel. If you have previously downloaded
		an earlier source package you will only need to download the much
		smaller patch file to bring those up to date. We will discuss patch application
		in the next section. There are also some <filename>.sign</filename> files
		that contain MD5 sum information.  (elaborate md5)
		</para>

		<para>
		The <ulink url="http://kernel.org"><citetitle>http://kernel.org</citetitle>
		</ulink> website is not the only place to retrieve patches. Many other vendors
		and individuals have developed patches to improve aspects of the kernel's
		performance, support new hardware, or introduce features that are too esoteric
		or experimental to make it to the stock kernel. For example, kernel hacker
		Robert Love had developed the <emphasis>pre-emptible</emphasis> kernel 
		modifications that made dramatic improvements to the responsiveness of a Linux
		system. These patches were not part of the standard 2.4.x kernel but were of
		such usefulness that they were officially adopted into the 2.6.0 series. For
		the most part these third-party patches are stable but do use your judgment when
		downloading and applying them.
		</para>
	</section>

	<section id="extract-patch">
		<title>Extract and Patch</title>
		<para>
		Once you have retrieved the kernel sources and patches, you will need to
		extract them and apply the patches. The pristine 2.4.x and 2.6.x sources can be
		built as a regular, unprivileged user and this is recommended. 
			<footnote>
			<para>
			Distributions will often install the kernel sources into     
			<filename>/usr/src/linux</filename>. To build in this directory
			will require root access. Note that there are usually two source packages --
			one called something like <filename>kernel-source-VERSION-i386.rpm</filename>
			and another called <filename>kernel-VERSION.src.rpm</filename>. You can generally
			rebuild the <filename>src.rpm</filename> as an unpriveleged user.
			</para>
			</footnote>
		</para>
	
		<para>	
		We will begin by creating a directory to hold all the source tarballs and patches,
		then proceed to extract the sources. For these examples we will assume that you 
		have previously downloaded an earlier release of the kernel and will now need to
		patch to bring it up to the current version.

		<screen>
			<prompt>$ </prompt><command>mkdir src</command>
			<prompt>$ </prompt><command>cd src</command>
		</screen>

		If your Linux sources are in BZIP compressed format (that is, end with a 
		<filename>.bz2</filename> extenstion, then use the following command:
		<screen>
			<prompt>$ </prompt><command>tar xfvj /path/to/linux-2.6.0-test7.tar.bz2</command>
		</screen>

		Otherwise, use the options for GZIP compressed data:

		<screen>
			<prompt>$ </prompt><command>tar xfvz /path/to/linux-2.6.0-test7.tar.gz</command>
		</screen>

		You should see a list of filenames scroll by as they are being extracted. Verify that
		the new kernel source directory is created:

		<screen>
			<prompt>$ </prompt><command>ls -l</command>
		</screen>
		<programlisting>
		total 4
		drwxr-xr-x   18 kwan   users   4096 Oct  8 15:24 linux-2.6.0-test7
		-rw-r--r--    1 kwan   users 276260 Nov 15 02:05 patch-2.6.0-test8.gz
		-rw-r--r--    1 kwan   users 126184 Nov 15 02:07 patch-2.6.0-test9.gz
		</programlisting>

		Next we must apply the patches in order. Patch files are created by the 
		<filename>diff</filename> program, and can selectively modify one or more files
		by adding, deleting, or modifying lines in the source code. Because they contain only
		the differences between files it is usually a lot faster (and better for the Internet
		in general) if you patch to the current release. (TBF unclear). Appendix TBF shows
		a typical patch file. Like the kernel sources, the patch files are also compressed. 

		<screen>
			<prompt>$ </prompt><command>gunzip patch-2.6.0-test8.gz</command>
			<prompt>$ </prompt><command>gunzip patch-2.6.0-test9.gz</command>
			<prompt>$ </prompt><command>ls -l</command>
		</screen>
		<programlisting>
		-rw-r--r--    1 kwan  users  1072806 Nov 15 02:05 patch-2.6.0-test8
		-rw-r--r--    1 kwan  users   486902 Nov 15 02:07 patch-2.6.0-test9
		</programlisting>

		Once the patches are uncompressed we can apply them to the kernel sources. Remember
		that it is important to apply them in order. 
		<screen>
			<prompt>$ </prompt><command>cd linux-2.6.0-test7</command>
			<prompt>$ </prompt><command>patch -p1 &lt;../patch-2.6.0.test8</command>
			<prompt>$ </prompt><command>patch -p1 &lt;../patch-2.6.0.test9</command>
		</screen>
	
		If it is successful you will see messages similar to the following scroll by:

		<programlisting>
		patching file Documentation/filesystems/jfs.txt
		patching file Documentation/filesystems/xfs.txt
		patching file Documentation/ia64/fsys.txt
		patching file Documentation/ide.txt
		patching file Documentation/x86_64/boot-options.txt
		patching file Makefile
		</programlisting>

		If unsuccessful you will get a warning and be prompted for a file to patch. If 
		this occurs, press <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo>
		to break out of the patch utility and verify that you are using the correct
		patch and applying them in the correct order. 
		</para>
		<para>
		Once all the patches are applied you might consider backing up the directory. 
			
		<screen>
			<prompt>$ </prompt><command>cd ..</command>
			<prompt>$ </prompt><command>mv linux-2.6.0-test7 linux-2.6.0-test9</command>
			<prompt>$ </prompt><command>tar cfvj linux-2.6.0-test9.tar.bz2 linux-2.6.0-test9</command>
		</screen>
		</para>
	</section>
</chapter>

<chapter id="configuration">
	<title>Configuration</title>
	<section id="configuration-intro">
		<title>The Configuration Process</title>
		<para>
			The configuration process is the most strenous portion of the kernel
			rebuild process. In this step you are deciding which features will be 
			included in the final kernel and it can require lots of hardware
			knowledge. In truth, it is not too onerous. The current kernels have
			graphical configuration programs and though not perfect, provide help
			screens for most of the configuration options.
		</para>
		<para>
			Many changes were made to the configuration subsystem in the 2.6.0 kernel
			series. It is easier to add modules and much more robust than before.
			It has also changed dramatically in appearance especially when using the
			X-based configuration tool, xconfig.  For this reason the configuration 
			steps for the different branches have been split into two sections in this 
			chapter. 
		</para>
		<para>
			As mentioned, both configuration tools provide context sensitive help 
			screens for the different options. Because this help is readily available
			to the user (and more importantly, because there are several hundred
			options) this guide will only cover a fraction of the choices. 
		</para>
	</section>

	<section id="module-or-static">
		<title>Compile Modules or Static</title>
		<para>
			One of the first choices you will make is whether or not to build device
			support directly into the kernel or as a module. In the early days of Linux,
			when module support was in its infancy, it is possible that static (i.e.,
			compiled in) drivers were faster. With any modern CPU the time to load and
			unload the modules and the memory required for the module loader subsystem
			is negligible even to benchmarking utilities. Some devices, notably the disk
			controller, can be built directly into the kernel in order to simplify 
			the boot process. 

			<footnote>
				<para>
		  		This is a relative thing. The initrd utility is robust and easy to
				use. Bootloaders have also improved to the point that little effort
				is saved by using static kernels. My two cents.
				</para>
			</footnote>
		</para>
		<para>
			You may also choose to disable some options entirely. Though you will not have any
			performance increases, there are advantages to disabling features that are not
			required. For one, the compile times will be drastically reduced depending on 
			which subsystem is disabled. For another, the final kernel and installed modules
			will require less space. On modern hard drives of 40G, 60G, and even 250G, an
			extra 20M or so is negligible but is significant on embedded or older systems.
			The disadvantage is that you will not have support for those features until you
			recompile the kernel. One other thing to keep in mind, as noted in
			KERNELTRAP.ORG (http://www.kerneltrap.org/node/view/799):

		<blockquote>
			<attribution>kerneltrap.org</attribution>
			<literallayout>
			Having unnecessary drivers will make the kernel bigger, and can under some 
			circumstances lead to problems: probing for a nonexistent controller card may 
			confuse your other controllers.
			</literallayout>
		</blockquote>

		</para>
</section>

	<section id="change-patchlevel">
		<title>Assign Unique Name</title>
		<para>
		We have so far extracted and patched the Linux sources. During our preparation
		we had also determined what hardware is installed in the system so that we will
		know which modules will need compilation. Before we proceed to actually configuring
		the kernel there are a couple minor but important details to complete. 
		</para>
		<para>
		Inside the Linux source directory is the default <filename>Makefile</filename>. This
		file is used by the <application>make</application> utility to compile the Linux
		sources. The first few lines of the <filename>Makefile</filename> contains some
		versioning information:

		<programlisting>
		VERSION = 2
		PATCHLEVEL = 4
		SUBLEVEL = 22
		EXTRAVERSION = -1
		</programlisting>

		Note that there is an additional EXTRAVERSION field. To prevent overwriting any
		existing kernel modules on the system we will change this EXTRAVERSION to something
		unique. When the final installation steps are run, kernel module files will then get
		written to 
		<filename>/lib/modules/$VERSION.$PATCHLEVEL.$SUBLEVEL-$EXTRAVERSION.</filename>
		</para>
	</section>
	<section id="backup-config">
		<title>Backup <filename>.config</filename></title>
		<para>
		Finally, before we begin, please note that the configuration choices are kept in the
		<filename>../linux/.config</filename> file. If you have not already run any configurations 
		this fill will not exist. If you have, and would like to save your configuration, copy the 
		<filename>.config</filename> to another file:

		<screen>
			<prompt>$ </prompt><command>cd linux</command>
			<prompt>$ </prompt><command>cp .config config.save</command>
		</screen>

		If you are using the sources from a vendor then the default configuration
		files are usually included in the <filename>configs</filename> or in the
		<filename>./arch/i386/defconfig</filename> (for i386 machines) file. You
		can use these configurations as a starting point for your customizations.
		The <filename>.config</filename> <emphasis>will</emphasis> be overwritten
		in the next step, so do make a backup before proceeding!
		</para>
			
		<para>
		We begin the configuration by wiping out all previous configurations
		and resetting the source directory to a pristine state. The main
		reason for doing this is that some files do not automatically get
		rebuilt which can lead to failed builds, or at worst, a buggy kernel.

		<screen>
			<prompt>$ </prompt><command>make mrproper</command>
		</screen>

		In the 2.4.x series, a few dozen lines of <command>rm -f</command> commands 
		will appear as all generated files get removed. The 2.6.0 process is less noisy and
		returns only a few CLEAN messages. Please note that it is generally safe to omit 
		the <command>make mrproper</command> step during subsequent rebuilds. 

		</para>
		<para>
		As of this writing (December 15, 2003), the 2.4.x kernel is in wide deployment.
		The 2.6.0 has just been released to the world. Though the configuration and
		build procedures are quite similar, there are enough differences to warrant
		separate sections for each kernel. If you are building a 2.6.0 series kernel,
		skip to <xref linkend="configuration-26">. Otherwise, proceed to the next section,
		<xref linkend="configuration-24">.
		</para>
	
	</section>

	<section id="configuration-24">
		<title>Configuring the 2.4.x kernels</title>
	
		<para>
		Our next step is to run the configuration utility. In the 2.4.x kernels there are 
		four main frontends: config, oldconfig, menuconfig, xconfig.  We choose one 
		configuration method and run it with, for example:

		<screen>
			<prompt>$ </prompt><command>make config</command>
		</screen>

		</para>
		<para>
		<command>config</command> is the least user-friendly option as it merely presents 
		a series of questions that must be answered sequentially. Alas, if an error is made 
		you must begin the process from the top. Pressing <keycap>Enter</keycap> will accept
		the default entry which is in upper case.
		</para>
		<para>
		<command>oldconfig</command> will read the defaults from an existing 
		<filename>.config</filename> and rewrite necessary links and files. Use this option
		if you've made minor changes to source files or need to script the rebuild process.
		Note that <command>oldconfig</command> will only work within the
		same major version of the kernel. You <emphasis>cannot</emphasis>,
		for example, use a 2.4.x <filename>.config</filename> with the
		2.6.x kernel.
		</para>
		<para>
		<command>menuconfig</command> is an <emphasis>ncurses</emphasis> based frontend.
		Your system must have the <filename>ncurses-devel</filename> libraries installed
		in order to use this utility. As the help text at the top of the screen indicates,
		use the arrow keys to navigate the menu. Press <keycap>Enter</keycap> to select
		sub-menus. Press the highlighted letter on each option to jump directly to that option.
		To build an option directly into the kernel, press <keycap>Y</keycap>. To disable an
		option entirely, press <keycap>N</keycap>. To build an option as a loadable module,
		press <keycap>M</keycap>. You can also access content-specific help screens by 
		pressing <keycap>?</keycap> on each page or selecting <command>HELP</command> from
		the lower menu. <xref linkend="menuconfig-graphic"> shows an example screen.
		<footnote>
			<para>
			I have noticed some minor screen corruption when using menuconfig in 
			slightly non-standard terminals. Though it functions normally some of the
			menu entries may be difficult to read until the screen is refreshed.
			</para>
		</footnote>
				
		<figure id="menuconfig-graphic">
			<title>make menuconfig</title>
			<mediaobject>
				<imageobject>
				<imagedata fileref="images/menuconfig.eps" format="eps" scale=25 scalefit="1">
				</imageobject>
				<imageobject><imagedata fileref="images/menuconfig.jpg" format="jpg"></imageobject>
					<textobject><phrase>make menuconfig example graphic</phrase></textobject>
					<caption><para></para></caption>
			</mediaobject>
		</figure>
		</para>

		<para>
		<command>xconfig</command>, as the name suggests, is an <application>X Window</application>
		based frontend. It requires the TCL/TK and X libraries to work, and of course, an X server.
		<xref linkend="xconfig-graphic"> shows an example screen.
			
		<figure id="xconfig-graphic">
			<title>make xconfig</title>
				<mediaobject>
			<imageobject>
					<imagedata fileref="images/xconfig.eps" format="eps" scale=25 scalefit="1">
				</imageobject>
				<imageobject><imagedata fileref="images/xconfig.jpg" format="jpg"></imageobject>
				<textobject><phrase>make xconfig example graphic</phrase></textobject>
				<caption><para></para></caption>
			</mediaobject>
		</figure>
		</para>

		<para>
		For the purposes of this next section we will assume that <command>make xconfig</command>
		is used. The options are identical otherwise. As mentioned, there are literally hundreds
		of configuration options and this precludes us from listing every one of them. If you 
		are unsure of an option use the online help or consult the kernel documentation found
		in the <filename>../linux/Documentation</filename> directory. We begin by typing:

		<screen>
			<prompt>$ </prompt><command>make xconfig</command>
		</screen>

		The main configuration menu will appear. Selecting an item will bring up another window
		with further options. These in turn can spawn other sub-menus. 

		<variablelist>
			<varlistentry>
				<term>Code Maturity Level Options</term>
				<listitem>
					<para>
					This option allows configuration of alpha-quality software. It is best
					to disable this option if the kernel is intended for a stable production
					system. If you require an experimental feature in the kernel, such as
					a driver for new hardware, then enable this option but be aware that 
					it <quote>may not meet the normal level of reliability</quote> as tested
					code. 
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Loadable Module Support</term>
				<listitem>
					<para>
						You will almost certainly want to enable module support. If you
						will need third-party kernel modules you will also need to
						enable <emphasis>Set Version Information on All Module Symbols</emphasis>.	
					 </para>
					</listitem>
			</varlistentry>
			<varlistentry>
				<term>Processor Type and Features</term>
				<listitem>
					<para>
						This is perhaps the most important option to choose. In the Preparation
						section we determined our processor type by examining 
						<filename>/proc/cpuinfo</filename> and we use that information here to
						select the appropriate processor. Included in this submenu are features
						such as <emphasis>Low Latency Scheduling</emphasis> which can improve
						desktop responsiveness, <emphasis>Symmetric Multi-processing Support</emphasis>
						for machines with multiple CPUs, and <emphasis>High Memory Support</emphasis>
						for machines with more than 1G of RAM. Laptop users can also benefit from
						the <emphasis>CPU Frequency Scaling</emphasis> feature.
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>General Setup</term>
				<listitem>
					<para>
						Choices for <acronym>PCI</acronym>, <acronym>ISA</acronym>,
						<acronym>PCMCIA</acronym> and other architectural support such as 
						<emphasis>Advanced Power Management</emphasis> are found here.
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term>Memory Technology Devices</term>
				<listitem>
					<para>
						<acronym>MTD</acronym> devices include <productname>Compact Flash</productname>
						devices. Some digital cameras will require this support.
						</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Block Devices</term>
				<listitem>
					<para>
						The Block Device section contains options for floppy and hard drives,
						including parallel port devices, tape drives and <acronym>RAID</acronym>
						controllers. Important options include loopback device support, which
						allows mounting on disk images, and initrd support, which is needed to
						preload drivers necessary to boot the system.
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Multi-Device support (<acronym>RAID</acronym> and <acronym>LVM</acronym>)</term>
				<listitem>
					<para>
						Important for servers, these options include <acronym>RAID</acronym> support
						for combining multiple disks. Note that this option is not needed for 
						certain hardware <acronym>RAID</acronym> that function below the operating
						system level. <acronym>LVM</acronym> is a useful subsystem that allows,
						among other things, dynamic resizing of filesystems.	
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term><acronym>ATA/IDE/MFM/RLL</acronym> support.</term>
				<listitem>
					<para>
						This section includes options for <acronym>IDE/ATAPI</acronym> chipsets,
						including performance tweaks such as <acronym>DMA</acronym>. Most systems
						will need this support.
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term>Cryptography Support (CryptoAPI)</term>
				<listitem>
					<para>
						Useful options include Loopback Crypto Support, which allows encrypted
						filesystem images to be mounted. Even with full access to the PC, 
						loopback encryption can help safeguard data.
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term>Networking Options</term>
				<listitem>
					<para>
					 	Many choices are available for networking. <acronym>TCP/IP</acronym>,
						<acronym>IP</acronym> tunneling, packet filtering, <acronym>IPv4</acronym>
						and <acronym>IPv6</acronym>, routing support and network QoS are among
						the most useful. If your kernel is intended for a dedicated firewall or
						router device then the options here can significantly improve performance.
						Read the online and kernel documentation.
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term><acronym>SCSI</acronym> Support</term>
				<listitem>
					<para>
						<acronym>SCSI</acronym> support is needed for not only true 
						<acronym>SCSI</acronym> devices, but also for <acronym>IDE</acronym>
						<acronym>CDR/W</acronym> drives in <acronym>SCSI</acronym> emulation
						mode. If your root filesystem is mounted on a <acronym>SCSI</acronym>
						disk then you must build support directly into the kernel and not as
						a module. 
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term>Character Devices</term>
				<listitem>
					<para>
						Dozens of options are available here, including support for many
						serial and parallel devices, hardware sensors (for system monitors),
						mice, joysticks and <acronym>DRM</acronym>. Many of the options can
						be safely disabled without problem.
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term>File Systems</term>
				<listitem>
					<para>
						It is a good idea to build support for your root filesystem directly
						into the kernel. Though the <application>initrd</application> utilities
						can get around the chicken-and-egg boot problem, it is generally safer
						and easier to just build the fs modules directly. Many options can also
						be safely disabled if you have no use for the feature.
					</para>
				</listitem>
			</varlistentry>
		</variablelist>
	</para>	
	<para>
		Once all the configuration changes have been made you can go ahead and save settings.
		By default the configuration is placed in the <filename>.config</filename> file
		in the topmost directory. Because this file is deleted in <command>make mrproper</command>
		and is also hidden, it is a good idea to use the <emphasis>Save to Alternate File</emphasis>
		before exiting. It will prompt for another save location. Enter something outside of the
		source tree and with a useful name such as <filename>kernel-2.4.22-lowlatency.config</filename>. 	
		Once this is done, exit the configuration menu. You will be prompted to save the
		configuration again. Select <command>Yes</command> and continue. 
	</para>
	<para>
		The configuration for the 2.4.x kernel is now complete. You may now skip to 
		<xref linkend="building">.
	</para>
	</section>

	<section id="configuration-26">
	<title>Configuring the 2.6.x kernels</title>
		<para>
		Our next step is to run the configuration utility. On the 2.6.x kernels there
		are four main frontend programs: config, menuconfig, and xconfig. 
		</para>
		<para>
		<command>config</command> is the least user-friendly option as it merely presents 
		a series of questions that must be answered sequentially. Alas, if an error is made 
		you must begin the process from the top. Pressing <keycap>Enter</keycap> will accept
		the default entry which is in upper case.
		</para>
		<para>
		<command>oldconfig</command> will read the defaults from an existing 
		<filename>.config</filename> and rewrite necessary links and files. Use this option
		if you've made minor changes to source files or need to script the rebuild process.
		</para>
		<para>
		<command>menuconfig</command> is an <emphasis>ncurses</emphasis> based frontend.
		Your system must have the <filename>ncurses-devel</filename> libraries installed
		in order to use this utility. As the help text at the top of the screen indicates,
		use the arrow keys to navigate the menu. Press <keycap>Enter</keycap> to select
		sub-menus. Press the highlighted letter on each option to jump directly to that option.
		To build an option directly into the kernel, press <keycap>Y</keycap>. To disable an
		option entirely, press <keycap>N</keycap>. To build an option as a loadable module,
		press <keycap>M</keycap>. You can also access content-specific help screens by 
		pressing <keycap>?</keycap> on each page or selecting <command>HELP</command> from
		the lower menu. <xref linkend="menuconfig-graphic"> shows an example screen from
		the 2.4.x kernel series.
		</para>
		<para>
		<command>xconfig</command> is a graphical frontend using <application>qconf</application>
		by Roman Zippel. It requires the <application>qt</application> and X libraries to 
		build and use. The interface is intuitive and customizable. Online help is automatically
		shown for each kernel configuration option. It also can show dependency information for
		each module which can help diagnose build errors. <xref
		linkend="xconfig26-graphic"> shows an
		example of the <command>xconfig</command> screen. 

		From the online help:
		<blockquote>
			<attribution>qconf help</attribution>
			<literallayout>
			For each option, a blank box indicates the feature is disabled, a check
			indicates it is enabled, and a dot indicates that it is to be compiled
			as a module. Clicking on the box will cycle through the three states.
			If you do not see an option (e.g., a device driver) that you believe
			should be present, try turning on Show All Options under the Options menu.
			Although there is no cross reference yet to help you figure out what other
			options must be enabled to support the option you are interested in, you can
			still view the help of a grayed-out option.
			</literallayout>
		</blockquote>

		<figure id="xconfig26-graphic">
			<title>make xconfig</title>
			<mediaobject>
				<imageobject>
					<imagedata fileref="images/xconfig2_6.eps" format="eps" scale=45 scalefit="1">
				</imageobject>
				<imageobject><imagedata fileref="images/xconfig2_6.jpg" format="jpg"></imageobject>
				<textobject><phrase>make xconfig example graphic</phrase></textobject>
				<caption><para></para></caption>
			</mediaobject>
		</figure>
		</para>
		<para>
		Once you have decided which configuration option to use, start the process with 
		<command>make</command> followed by either <command>config</command>, 
		<command>menuconfig</command>, or <command>xconfig</command>. For example:

		<screen>
		 	<prompt>$ </prompt><command>make menuconfig</command>
		</screen>

		The system will take a few moments to build the configuration utility. Next you
		will be presented with the configuration menus. Though similar to the 2.4.x series,
		the 2.6.x menu is more logically organized with better grouping of sub-modules.
		Following are some of the top level configuration options in the 2.6 kernel.
		</para>
		
	<para>
		<variablelist>
			<varlistentry>
				<term>Code Maturity Level Options</term>
				<listitem>
					<para>
						This option allows configuration of alpha-quality software or obsoleted
						drivers. It is best to disable this option if the kernel is intended for 
						a stable production system. If you require an experimental feature in the 
						kernel, such as a driver for new hardware, then enable this option but be 
						aware that it <quote>may not meet the normal level of reliability</quote> 
						as more regorously tested code. 
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term>General Setup</term>
				<listitem>
					<para>
						This section contains options for <command>sysctl</command> support,
						a feature allowing run-time configuration of the kernel. A new feature,
						kernel <filename>.config</filename> support, allows the complete 
						kernel configuration to be viewed during run-time. This addresses 
						many requests to be able to see what features were compiled into
						the kernel.
					</para>
				</listitem>
			</varlistentry>

			<varlistentry>
				<term>Loadable Module Support</term>
				<listitem>
					<para>
						You will almost certainly want to enable module support. If you
						will need third-party kernel modules you will also need to
						enable <emphasis>Set Version Information on All Module Symbols</emphasis>.	
					 </para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Processor Type and Features</term>
				<listitem>
					<para>
						This is perhaps the most important configuration choice. In the Preparation
						section we determined our processor type by examining 
						<filename>/proc/cpuinfo</filename> and we use that information here to
						select the appropriate processor. Included in this submenu are features
						such as <emphasis>Preemptible Kernel</emphasis> which can improve
						desktop responsiveness, <emphasis>Symmetric Multi-processing Support</emphasis>
						for machines with multiple CPUs, and <emphasis>High Memory Support</emphasis>
						for machines with more than 1G of RAM. 
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Power Management Options</term>
				<listitem>
					<para>
						Found here are options for <acronym>ACPI</acronym> and <acronym>CPU</acronym>
						Frequency Scaling which can dramatically improve laptop power usage. Read 
						the <filename>Documentation/power</filename> file for more information.
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Bus Options (<acronym> PCI, PCMCIA, EISA, MCA, ISA</acronym>)</term>
				<listitem>
					<para>
						Here are found options for all system bus devices. On modern machines
						the <acronym>ISA</acronym> and <acronym>MCA</acronym> support can often
						be disabled. 
					</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term>Executable File Formats</term>
				<listitem>
					<para>
						Interesting features here include the kernel support for miscellaneous
						binaries, which can allow seamless operation of non-Linux binaries
						with a little userland help.
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term>Device Drivers</term>
				<listitem>
					<para>
						All the configuration options that were previously scattered throughout
						the 2.4.x menus are now neatly organized under this option. Features
						such as <acronym>SCSI</acronym> support, graphic card optimizations,
						sound, <acronym>USB</acronym> and other hardware are configured here.
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term>File Systems</term>
				<listitem>
					<para>
						Found here are options for which filesystems are supported by the 
						kernel such as <acronym>EXT2</acronym> and ReiserFS. It is best to
						build support for the root filesystems directly into the kernel rather
						than as a module. 
					</para>
				</listitem>
			</varlistentry>
			
			<varlistentry>
				<term>Security Options</term>
				<listitem>
					<para>
						Interesting options here include support for <acronym>NSA</acronym>
						Security Enhanced Linux and other, somewhat experimental, features
						to increase security.
					</para>
				</listitem>
			</varlistentry>
		</variablelist>
	</para>

	</section>

</chapter> <!-- configuration -->

<chapter id="building">
	<title>Build</title>
	<section id="make-dep-clean">
		<title>Dependencies</title>
		<para>
		The next step is to create the necessary include files and generate dependency information. This
		step is only required for the 2.4.x kernel tree. 
		<screen>
			<prompt>$</prompt><command>make dep</command>
		</screen>

		Lots of messages will scroll by. Depending on the speed of your machine and on
		what options you chose, this may take several minutes to complete. Once the dependency 
		information is created we can clean up some miscellaneous object files. This step
		is required for all versions of the kernel.

		<screen>
			<prompt>$</prompt><command>make clean</command>
		</screen>

		</para>
	</section>

	<section id="make-image">
		<title>Build the Kernel</title>
		<para>
		We are now (finally) ready to start the actual kernel build. At the prompt type:

		<screen>
			<prompt>$</prompt><command>make bzImage</command>
		</screen>

		As the Kbuild documentation states:
		<blockquote>
			<attribution>Kbuild 2.4 Documentation</attribution>
			<literallayout>
			Some computers won't work with 'make bzImage', either due to hardware
			problems or very old versions of lilo or loadlin. If your kernel image
			is small, you may use 'make zImage', 'make zdisk', or 'make zlilo'
			on these systems.
			</literallayout>
		</blockquote>


		<footnote>
			<para>
			The difference between 'zImage' files and 'bzImage' files is that
			'bzImage' uses a different layout and a different loading algorithm,
			and thus has a larger capacity. Both files use gzip compression. The
			'bz' in 'bzImage' stands for 'big zImage', not for 'bzip'!
			</para>
		</footnote>

		On an Athlon 1800XP, building the bzImage took approximately seven
		minutes for a moderately configured kernel. On a Pentium 100 used as a 
		baseline, a similar configuration took almost 45 minutes. If you are not 
		in a hurry you may want to start the build on a console while you continue to work. 

		The main difference between the 2.4 and 2.6 trees is the amount of information
		presented on the screen. Much less information is displayed with 2.6.0 making
		errors and warnings easier to spot.

		If everything went correctly then the new kernel should exist in 
		<filename>./arch/$ARCH/boot</filename>. For example, on IA32 
		systems we can verify this with:

		<screen>
			<prompt>$</prompt><command>ls -l arch/i386/boot</command>
		</screen>

	
		</para>
	</section>

	<section id="make-modules">
		<title>Build the Modules</title>
		<para>

		There is one more step needed for the build process, however. You have created the 
		kernel, but now you need to create all the loadable modules if you have them
		configured.  Be aware that typical distribution kernels tend to have almost every
		feature installed, plus a few others for good measure. These can typically take
		and hour or so to build on our Athlon XP1800. The stock kernels are somewhat 
		leaner by default and take, on average, 25 minutes to compile. To build the modules
		we run:

		<screen>
			<prompt>$ </prompt><command>make modules</command>
		</screen>

		Again, lots of messages will scroll by on the screen. Here also the 2.6.0 series
		is less talkative, outputting only summary information. Once the modules are built
		they can be installed. If you were building as a non-privileged user you will now 
		need to switch to root to complete this next step:

		<screen>
			<prompt>$ </prompt><command>su</command>
			password:
			<prompt>$ </prompt><command>make modules_install</command>
		</screen>

		The freshly baked modules will be copied into <filename>/lib/modules/KERNEL_VERSION</filename>.

		</para>
	</section>

	<section id="mkinitrd">
		<title>Create Initial RAMDisk</title>
		<para>
			If you have built your main boot drivers as modules (e.g., SCSI host
			adapter, filesystem, RAID drivers) then you will need to create an 
			initial RAMdisk image. The initrd is a way of sidestepping the chicken
			and egg problem of booting -- drivers are needed to load the root
			filesystem but the filesystem cannot be loaded because the drivers
			are on the filesystem.  As the manpage for <command>mkinitrd</command>
			states:

		<blockquote>
			<attribution>MKINITRD(8)</attribution>
			<literallayout>
	       mkinitrd creates filesystem images which are suitable for use as Linux initial
	       ramdisk(initrd) images. Such images are often used for preloading  the
	       block device modules (such as IDE, SCSI or RAID) which are needed to access the
	       root filesystem. mkinitrd automatically loads filesystem  modules (such as
	       ext3 and jbd), IDE modules,all scsi_hostadapter entries in /etc/modules.conf,
	       and raid modules if the systems root partition is on raid, which makes it
	       simple to build and use kernels using modular device drivers.
			</literallayout>
		</blockquote>

			To create the initrd, do the following:
			<screen>
				<prompt>$ </prompt><command>mkinitrd /boot/initrd-2.6.0.img 2.6.0</command>
			</screen>

			Some versions of mkinitrd may require other options to specify
			the location of the new kernel. On SuSe 9.0, for example, the
			following syntax is required:

			<screen>
				<prompt>$ </prompt><command>mkinitrd -k vmlinux-VERSION -i initrd-VERSION</command>
			</screen>

			<footnote>
				<para>
				At this writing there are some issues with the modules.conf when moving
				from 2.4 to 2.6 kernels. Some module names have changed which seems to 
				cause glitches with initrd. 
				</para>
			</footnote>
		</para>
	</section>

			
	<section id="troubleshooting">
		<title>Troubleshooting Build Failures</title>
		<para>
			If your build fails with a signal 11 error it is most likely because of
			hardware problems; often the culprit is failing memory. Unfortunately,
			the BIOS memory check is close to useless in detecting intermittent
			memory failures. Even dedicated memory checkers do not stress memory
			as much as gcc running a kernel build. One way to tell if hardware is
			at fault is to restart the 'make bzImage' process. If you can get a
			little further before failing again then it is a hardware error. There
			are several possible way to try to correct these.
		</para>
		<para>
			Try changing your memory settings in the BIOS to more conservative
			levels. For example, change to SLOW or NORMAL instead of FAST. Verify
			that all the fans are working correctly.
			<footnote>
				<para> 
				For a long while, I thought that the xmatrix screensaver was
				crashing my machine because of the numerous core dumps I would
				discover in my home directory. It turned out that xmatrix was
				cpu intensive. Unknown to me, the CPU fan on this machine had
				failed. Everything was fine until xmatrix started, causing the
				processor to overheat, eventually leading to a crash.
				</para>
			</footnote>
			 Swap out the memory. One trick is to specify less memory than is
			 actually installed by passing values to the kernel on boot. This
			 prevents the kernel from accessing all the memory in the machine,
			 and could help diagnose bad SIMMs or SDRAMs.
		</para>
		<para>
			If instead the 'make' fails at the same point each time, then it is a
			configuration error. These usually result from not enabling a feature
			that is required by another. For example, IP Firewalling requires
			TCP/IP. If the prerequisite is not enabled, the build will fail. You
			may also get errors if you select the wrong processor or are using
			either a very old or development compiler.
		</para>
		<para>
			Also keep in mind that the kernel is highly sensitive to the versions
			of the build tools such as the compiler and linker. Double check that
			your tools and libraries are the minimum <emphasis>required</emphasis>,
			not <emphasis>suggested</emphasis> for a clean build.
		</para>
	</section>
</chapter>

<chapter>
 	<title>Installation</title>
	<section id="installation">
		<title>Copy the Kernel and System.map</title>
		<para>
		Once your kernel is created, you can prepare it for use. From the
		<filename>./linux</filename> directory, copy the kernel and 
		<filename>System.map</filename> file to /boot. In the following
		examples change KERNEL_VERSION to the version of your kernel.
		<footnote>
		<para>
			Jerome Walter offers the following information for PowerPPC
			plaforms:
			
			On a PowerPC (PreP architecture). To make the system bootable, one 
			needs to copy the bzImage file into the special partition (PreP Boot 
			Partition type 41), dusing dd. Assuming that the so called partition 
			is named /dev/sda1, the command should look like :
			<screen>
			<prompt>$ </prompt><command>dd if=bzImage-you-have-just-done.img of=/dev/sda1</command>
			</screen>

			People should be warned that if their partition is too small, the
			bzImage will not fit, and the boot procedure will fail.
		</para>
		</footnote>

		<screen>
			<prompt>$ </prompt><command>cp arch/i386/boot/bzImage /boot/bzImage-KERNEL_VERSION</command>
			<prompt>$ </prompt><command>cp System.map /boot/System.map-KERNEL_VERSION</command>
			<prompt>$ </prompt><command>ln -s /boot/System.map-KERNEL_VERSION /boot/System.map</command>
		</screen>
		</para>

		<para>
		The next step is to configure your bootloader. The bootloader is the
		first program that runs when a computer is booted. For this document it is
		assumed that you are running an IA32 system with a standard PC BIOS. If
		you are running the <productname><acronym>LiLO</acronym></productname>
		bootloader skip to the <xref linkend="lilo-configuration"> otherwise
		proceed to <xref linkend="grub-configuration">.
		</para>
		<para>
		FIXME: Need information on non-IA32 bootloaders!!
		</para>
	</section>


	<section id="grub-configuration">
		<title>GrUB Configuration</title>
		<para>
		GrUB is beginning to supplant LiLO as the bootloader of choice in more 
		recent Linux distributions. It is generally more flexible and a lot more
		forgiving of system errors. For example, LiLO generally requires that an alternate boot
		disk is used if the kernel configuration renders the system unbootable 
		Grub allows <quote>on-the-fly</quote> modification of kernel location, 
		boot parameters, kernel to boot, etc..	
		</para>
		<para>
		Once you have copied the bzImage and System.map to <filename>/boot</filename>,
		edit the grub configuration file located in <filename>/boot/grub/menu.lst</filename>.
		On some distributions <filename>/etc/grub.conf</filename> is a symbolic link to
		this file. 

		<programlisting>
		# Note that you do not have to rerun grub after making changes to this file
		#boot=/dev/hda
		default=0
		timeout=10
		title Red Hat Linux (2.4.20-24.9)
			root (hd0,1)
			kernel /boot/vmlinuz-2.4.20-24.9 ro root=LABEL=/
			initrd /boot/initrd-2.4.20-24.9.img
		title Red Hat Linux (2.4.20-20.9)
			root (hd0,1)
			kernel /boot/vmlinuz-2.4.20-20.9 ro root=LABEL=/
			initrd /boot/initrd-2.4.20-20.9.img
		</programlisting>

		Edit the file to include your new kernel information. Keep in mind that GrUB counts
		starting from 0, so (hd0,1) references the first controller, <emphasis>second</emphasis>
		partition. If you have created an initial RAMdisk be sure to include it here too. 
		A typical configuration may look something like this:

		<programlisting>
		title Test Kernel (2.6.0)
			root (hd0,1)
			kernel /boot/bzImage-2.6.0 ro root=LABEL=/
			initrd /boot/initrd-2.6.0.img
		</programlisting>
		</para>
	</section>

	<section id="lilo-configuration">
		<title>LiLO Configuration</title>
		<para>
		LiLO is an older bootloader. Its configuration file is located in 
		<filename>/etc/lilo.conf</filename> on most systems. Unlike GrUB,
		any changes to lilo.conf will not be set until the lilo program is
		rerun. 
		
		<programlisting>
		boot=/dev/hda
		map=/boot/map
		install=/boot/boot.b
		default=test-2.6.0
		keytable=/boot/us.klt
		lba32
		prompt
		timeout=50
		message=/boot/message
		menu-scheme=wb:bw:wb:bw
		image=/boot/vmlinuz
			label=linux
			root=/dev/hda3
			append=" ide1=autotune ide0=autotune"
			read-only
		  
		image=/boot/bzImage-2.6.0
			label=test-2.6.0
			root=/dev/hda2
			read-only
		</programlisting>  

		The important sections are the <emphasis>image=/boot/bzImage</emphasis> and 
		the <emphasis>default=test-2.6.0</emphasis> options. Notice that you can have 
		several image sections in the lilo.conf, allowing multiple configurations.
		Install the new kernel by running the lilo program.

  		<screen>
		<prompt>$ </prompt><command> /sbin/lilo</command>
		</screen>

		If you are installing and testing the kernel remotely, you can
		instead specify to LiLO that the new kernel is loaded only for the next
		boot by using the following syntax:
		<screen>
		<prompt>$ </prompt><command> /sbin/lilo -R test-2.6.0</command>
		</screen>


		Messages will appear showing the newly added kernel with an asterisk marking
		the default image. If you get errors, consult the lilo documentation for the
		correct syntax.
		</para>
	</section>
</chapter>

<appendix id="about">
	<title>Feedback</title>
	<section id="about-feedback">
		<title>Comments and corrections</title>

			<para>
				The current maintainer of this <citetitle>HOWTO</citetitle>
				is <author><firstname>Kwan</firstname>
				<surname>Lowe</surname></author>.  Please send corrections,
				additions, comments and criticisms to
				<email>kwan@digitalhermit.com</email>.
			</para>

			<para>
				The maintainer would also appreciate e-mails from people that
				have sucessfully used this <citetitle>HOWTO</citetitle> to
				configure and use the DocBook .  Please state the
				version of the <citetitle>HOWTO</citetitle> you used (see the cover
				page), your <systemitem class="osname">Linux</systemitem>
				distribution and its version.
			</para>

			<para>
				The <citetitle>HOWTO</citetitle>'s maintainer is not a
				professional writer.  If you find some parts of this
				<citetitle>HOWTO</citetitle> difficult to comprehend then let the
				maintainer know.
			</para>
	</section> <!-- about-feedback -->
</appendix> <!-- about -->


<colophon id="colophon">

	<para>
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</colophon> <!-- colophon -->

</book>