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- <?xml version="1.0" encoding="ISO-8859-1"?>
- <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
- <!ENTITY % general-entities SYSTEM "../general.ent">
- %general-entities;
- ]>
- <sect1 id="ch-bootable-grub">
- <title>Making the LFS system bootable</title>
- <?dbhtml filename="grub.html"?>
- <indexterm zone="ch-bootable-grub">
- <primary sortas="a-Grub">Grub</primary>
- <secondary>configuring</secondary></indexterm>
- <para>Your shiny new LFS system is almost complete. One of the last things to
- do is ensure you can boot it. The instructions below apply only to computers of
- IA-32 architecture, meaning mainstream PCs. Information on <quote>boot
- loading</quote> for other architectures should be available in the usual
- resource-specific locations for those architectures.</para>
- <para>Boot loading can be a complex area. First, a few cautionary words. You
- really should be familiar with your current boot loader and any other
- operating systems present on your hard drive(s) that you might wish to keep
- bootable. Please make sure that you have an emergency boot disk ready, so that
- you can rescue your computer if, by any chance, your computer becomes unusable
- (un-bootable).</para>
- <para>Earlier, we compiled and installed the Grub boot loader software in
- preparation for this step. The procedure involves writing some special Grub
- files to specific locations on the hard drive. Before we get to that, we
- highly recommend that you create a Grub boot floppy diskette just in case.
- Insert a blank floppy diskette and run the following commands:</para>
- <screen><userinput>dd if=/boot/grub/stage1 of=/dev/fd0 bs=512 count=1
- dd if=/boot/grub/stage2 of=/dev/fd0 bs=512 seek=1</userinput></screen>
- <para>Remove the diskette and store it somewhere safe. Now we'll run the
- <userinput>grub</userinput> shell:</para>
- <screen><userinput>grub</userinput></screen>
- <para>Grub uses its own naming structure for drives and partitions, in the form
- of (hdn,m), where <emphasis>n</emphasis> is the hard drive number, and
- <emphasis>m</emphasis> the partition number, both starting from zero. This
- means, for instance, that partition <filename>hda1</filename> is (hd0,0) to
- Grub, and <filename>hdb2</filename> is (hd1,1). In contrast to Linux, Grub
- doesn't consider CD-ROM drives to be hard drives, so if you have a CD on
- <filename>hdb</filename>, for example, and a second hard drive on
- <filename>hdc</filename>, that second hard drive would still be (hd1).</para>
- <para>Using the above information, determine the appropriate designator for
- your root partition (or boot partition, if you use a separate one). For the
- following example, we'll assume your root (or separate boot) partition is
- <filename>hda4</filename>.</para>
- <para>First, tell Grub where to search for its <filename>stage{1,2}</filename>
- files -- you can use the Tab key everywhere to make Grub show the alternatives:</para>
- <screen><userinput>root (hd0,3)</userinput></screen>
- <warning><para>The following command will overwrite your current boot loader.
- Don't run the command if this is not what you want. For example, you may be
- using a third party boot manager to manage your MBR (Master Boot Record). In
- this scenario, it would probably make more sense to install Grub into the
- <quote>boot sector</quote> of the LFS partition, in which case this next command
- would become: <userinput>setup (hd0,3)</userinput>.</para></warning>
- <para>Tell Grub to install itself into the MBR (Master Boot Record) of
- <filename>hda</filename>:</para>
- <screen><userinput>setup (hd0)</userinput></screen>
- <para>If all is well, Grub will have reported finding its files in
- <filename>/boot/grub</filename>. That's all there is to it:</para>
- <screen><userinput>quit</userinput></screen>
- <para>Now we need to create a <quote>menu list</quote> file, defining Grub's
- boot menu:</para>
- <screen><userinput>cat > /boot/grub/menu.lst << "EOF"</userinput>
- # Begin /boot/grub/menu.lst
- # By default boot the first menu entry.
- default 0
- # Allow 30 seconds before booting the default.
- timeout 30
- # Use prettier colors.
- color green/black light-green/black
- # The first entry is for LFS.
- title LFS &milestone; (Linux &linux-version;)
- root (hd0,3)
- kernel --no-mem-option /boot/lfskernel-&linux-version; root=/dev/hda4
- <userinput>EOF</userinput></screen>
- <note><para>By default, Grub will automatically pass a <quote>mem=xxx</quote>
- command line argument to the kernel. However, Grub occasionally gets the amount
- of memory wrong which can lead to problems in some circumstances. It's best to
- disable this functionality and let the kernel determine the amount of memory
- itself, hence the use of the <emphasis>--no-mem-option</emphasis> above.</para>
- </note>
- <para>You may want to add an entry for your host distribution. It might look
- like this:</para>
- <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
- title Red Hat
- root (hd0,2)
- kernel /boot/kernel-2.4.20 root=/dev/hda3
- initrd /boot/initrd-2.4.20
- <userinput>EOF</userinput></screen>
- <para>Also, if you happen to dual-boot Windows, the following entry should
- allow booting it:</para>
- <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
- title Windows
- rootnoverify (hd0,0)
- chainloader +1
- <userinput>EOF</userinput></screen>
- <para>If <command>info grub</command> doesn't tell you all you want to
- know, you can find more information regarding Grub on its website, located at:
- <ulink url="http://www.gnu.org/software/grub/"/>.</para>
- </sect1>
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