1 | <sect1 id="ch-bootable-grub">
|
---|
2 | <title>Making the LFS system bootable</title>
|
---|
3 | <?dbhtml filename="grub.html" dir="chapter08"?>
|
---|
4 |
|
---|
5 | <para>Your shiny new LFS system is almost complete. One of the last things to
|
---|
6 | do is ensure you can boot it. The instructions below apply only to computers of
|
---|
7 | IA-32 architecture, meaning mainstream PCs. Information on "boot loading" for
|
---|
8 | other architectures should be available in the usual resource specific
|
---|
9 | locations for those architectures.</para>
|
---|
10 |
|
---|
11 | <para>Boot loading can be a complex area. First, a few cautionary words. You
|
---|
12 | really should be familiar with your current boot loader and any other
|
---|
13 | operating systems present on your hard drive(s) that you might wish to keep
|
---|
14 | bootable. Please make sure that you have an emergency boot disk ready, so that
|
---|
15 | you can rescue your computer if, by any chance, your computer becomes unusable
|
---|
16 | (unbootable).</para>
|
---|
17 |
|
---|
18 | <para>Earlier, we compiled and installed the Grub boot loader software in
|
---|
19 | preparation for this step. The procedure involves writing some special Grub
|
---|
20 | files to specific locations on the hard drive. Before we get to that, we
|
---|
21 | highly recommend that you create a Grub boot floppy diskette just in case.
|
---|
22 | Insert a blank floppy diskette and run the following commands:</para>
|
---|
23 |
|
---|
24 | <screen><userinput>dd if=/boot/grub/stage1 of=/dev/fd0 bs=512 count=1
|
---|
25 | dd if=/boot/grub/stage2 of=/dev/fd0 bs=512 seek=1</userinput></screen>
|
---|
26 |
|
---|
27 | <para>Remove the diskette and store it somewhere safe. Now we'll run the
|
---|
28 | <userinput>grub</userinput> shell:</para>
|
---|
29 |
|
---|
30 | <screen><userinput>grub</userinput></screen>
|
---|
31 |
|
---|
32 | <para>Grub uses its own naming structure for drives and partitions, in the form
|
---|
33 | of (hdn,m), where <emphasis>n</emphasis> is the hard drive number, and
|
---|
34 | <emphasis>m</emphasis> the partition number, both starting from zero. This
|
---|
35 | means, for instance, that partition <filename>hda1</filename> is (hd0,0) to
|
---|
36 | Grub, and <filename>hdb2</filename> is (hd1,1). In contrast to Linux, Grub
|
---|
37 | doesn't consider CD-ROM drives to be hard drives, so if you have a CD on
|
---|
38 | <filename>hdb</filename>, for example, and a second hard drive on
|
---|
39 | <filename>hdc</filename>, that second hard drive would still be (hd1).</para>
|
---|
40 |
|
---|
41 | <para>Using the above information, determine the appropriate designator for
|
---|
42 | your root partition (or boot partition, if you use a separate one). For the
|
---|
43 | following example, we'll assume your root (or separate boot) partition is
|
---|
44 | <filename>hda4</filename>.</para>
|
---|
45 |
|
---|
46 | <para>First, tell Grub where to search for its <filename>stage{1,2}</filename>
|
---|
47 | files -- you can use Tab everywhere to make Grub show the alternatives:</para>
|
---|
48 |
|
---|
49 | <screen><userinput>root (hd0,3)</userinput></screen>
|
---|
50 |
|
---|
51 | <!-- HACK - Force some whitespace to appease tidy -->
|
---|
52 | <literallayout></literallayout>
|
---|
53 |
|
---|
54 | <warning><para>The following command will overwrite your current boot loader.
|
---|
55 | Don't run the command if this is not what you want. For example, you may be
|
---|
56 | using a third party boot manager to manage your MBR (Master Boot Record). In
|
---|
57 | this scenario, it would probably make more sense to install Grub into the
|
---|
58 | "boot sector" of the LFS partition, in which case the command would become:
|
---|
59 | <userinput>setup (hd0,3)</userinput>.</para></warning>
|
---|
60 |
|
---|
61 | <!-- HACK - Force some whitespace to appease tidy -->
|
---|
62 | <literallayout></literallayout>
|
---|
63 |
|
---|
64 | <para>Then tell it to install itself into the MBR (Master Boot Record) of
|
---|
65 | <filename>hda</filename>:</para>
|
---|
66 |
|
---|
67 | <screen><userinput>setup (hd0)</userinput></screen>
|
---|
68 |
|
---|
69 | <para>If all is well, Grub will have reported finding its files in
|
---|
70 | <filename>/boot/grub</filename>. That's all there is to it:</para>
|
---|
71 |
|
---|
72 | <screen><userinput>quit</userinput></screen>
|
---|
73 |
|
---|
74 | <para>Now we need to create a "menu list" file, defining Grub's boot
|
---|
75 | menu:</para>
|
---|
76 |
|
---|
77 | <screen><userinput>cat > /boot/grub/menu.lst << "EOF"</userinput>
|
---|
78 | # Begin /boot/grub/menu.lst
|
---|
79 |
|
---|
80 | # By default boot the first menu entry.
|
---|
81 | default 0
|
---|
82 |
|
---|
83 | # Allow 30 seconds before booting the default.
|
---|
84 | timeout 30
|
---|
85 |
|
---|
86 | # Use prettier colors.
|
---|
87 | color green/black light-green/black
|
---|
88 |
|
---|
89 | # The first entry is for LFS.
|
---|
90 | title LFS &milestone;
|
---|
91 | root (hd0,3)
|
---|
92 | kernel --no-mem-option /boot/lfskernel root=/dev/hda4
|
---|
93 | <userinput>EOF</userinput></screen>
|
---|
94 |
|
---|
95 | <note><para>By default, Grub will automatically pass a "mem=xxx" command line
|
---|
96 | argument to the kernel. However, Grub occasionally gets the amount of memory
|
---|
97 | wrong which can lead to problems in some circumstances. It's best to disable
|
---|
98 | this functionality and let the kernel determine the amount of memory itself,
|
---|
99 | hence the use of the <emphasis>--no-mem-option</emphasis> above.</para></note>
|
---|
100 |
|
---|
101 | <para>You may want to add an entry for your host distribution. It might look
|
---|
102 | like this:</para>
|
---|
103 |
|
---|
104 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
|
---|
105 | title Red Hat
|
---|
106 | root (hd0,2)
|
---|
107 | kernel /boot/kernel-2.4.20 root=/dev/hda3
|
---|
108 | initrd /boot/initrd-2.4.20
|
---|
109 | <userinput>EOF</userinput></screen>
|
---|
110 |
|
---|
111 | <para>Also, if you happen to dual-boot Windows, the following entry should
|
---|
112 | allow booting it:</para>
|
---|
113 |
|
---|
114 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
|
---|
115 | title Windows
|
---|
116 | rootnoverify (hd0,0)
|
---|
117 | chainloader +1
|
---|
118 | <userinput>EOF</userinput></screen>
|
---|
119 |
|
---|
120 | <para>If <command>info grub</command> doesn't tell you all you want to
|
---|
121 | know, you can find more information regarding Grub on its website, located at:
|
---|
122 | <ulink url="http://www.gnu.org/software/grub/"/>.</para>
|
---|
123 |
|
---|
124 | </sect1>
|
---|
125 |
|
---|