[3be4d97] | 1 | <sect1 id="ch-bootable-grub">
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[955533b] | 2 | <title>Making the LFS system bootable</title>
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| 3 | <?dbhtml filename="grub.html" dir="chapter08"?>
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| 4 |
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[e3a72b1] | 5 | <para>Your shiny new LFS system is almost complete. One of the last things to
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[5cd6caa] | 6 | do is ensure you can boot it. The instructions below apply only to computers of
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| 7 | IA-32 architecture, meaning mainstream PCs. Information on "boot loading" for
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[e3a72b1] | 8 | other architectures should be available in the usual resource specific
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| 9 | locations for those architectures.</para>
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| 10 |
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| 11 | <para>Boot loading can be a complex area. First, a few cautionary words. You
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| 12 | really should be familiar with your current boot loader and any other
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| 13 | operating systems present on your hard drive(s) that you might wish to keep
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| 14 | bootable. Please make sure that you have an emergency boot disk ready, so that
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| 15 | you can rescue your computer if, by any chance, your computer becomes unusable
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| 16 | (unbootable).</para>
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| 17 |
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| 18 | <para>Earlier, we compiled and installed the Grub boot loader software in
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| 19 | preparation for this step. The procedure involves writing some special Grub
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| 20 | files to specific locations on the hard drive. Before we get to that, we
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| 21 | highly recommend that you create a Grub boot floppy diskette just in case.
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| 22 | Insert a blank floppy diskette and run the following commands:</para>
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| 23 |
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| 24 | <screen><userinput>dd if=/boot/grub/stage1 of=/dev/fd0 bs=512 count=1
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| 25 | dd if=/boot/grub/stage2 of=/dev/fd0 bs=512 seek=1</userinput></screen>
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| 26 |
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| 27 | <para>Remove the diskette and store it somewhere safe. Now we'll run the
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[360e2c4] | 28 | <userinput>grub</userinput> shell:</para>
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[1561534] | 29 |
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[21ba4e3] | 30 | <screen><userinput>grub</userinput></screen>
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[1561534] | 31 |
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[54ff0b9] | 32 | <para>Grub uses its own naming structure for drives and partitions, in the form
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| 33 | of (hdn,m), where <emphasis>n</emphasis> is the hard drive number, and
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| 34 | <emphasis>m</emphasis> the partition number, both starting from zero. This
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| 35 | means, for instance, that partition <filename>hda1</filename> is (hd0,0) to
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| 36 | Grub, and <filename>hdb2</filename> is (hd1,1). In contrast to Linux, Grub
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| 37 | doesn't consider CD-ROM drives to be hard drives, so if you have a CD on
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| 38 | <filename>hdb</filename>, for example, and a second hard drive on
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| 39 | <filename>hdc</filename>, that second hard drive would still be (hd1).</para>
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[1561534] | 40 |
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[54ff0b9] | 41 | <para>Using the above information, determine the appropriate designator for
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[5cd6caa] | 42 | your root partition (or boot partition, if you use a separate one). For the
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| 43 | following example, we'll assume your root (or separate boot) partition is
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| 44 | <filename>hda4</filename>.</para>
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[1561534] | 45 |
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[54ff0b9] | 46 | <para>First, tell Grub where to search for its <filename>stage{1,2}</filename>
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| 47 | files -- you can use Tab everywhere to make Grub show the alternatives:</para>
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[1561534] | 48 |
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[21ba4e3] | 49 | <screen><userinput>root (hd0,3)</userinput></screen>
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[1561534] | 50 |
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[e3a72b1] | 51 | <!-- HACK - Force some whitespace to appease tidy -->
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| 52 | <literallayout></literallayout>
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| 53 |
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| 54 | <warning><para>The following command will overwrite your current boot loader.
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| 55 | Don't run the command if this is not what you want. For example, you may be
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| 56 | using a third party boot manager to manage your MBR (Master Boot Record). In
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| 57 | this scenario, it would probably make more sense to install Grub into the
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[360e2c4] | 58 | "boot sector" of the LFS partition, in which case the command would become:
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| 59 | <userinput>setup (hd0,3)</userinput>.</para></warning>
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[e3a72b1] | 60 |
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| 61 | <!-- HACK - Force some whitespace to appease tidy -->
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| 62 | <literallayout></literallayout>
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| 63 |
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[54ff0b9] | 64 | <para>Then tell it to install itself into the MBR (Master Boot Record) of
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| 65 | <filename>hda</filename>:</para>
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[1561534] | 66 |
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[21ba4e3] | 67 | <screen><userinput>setup (hd0)</userinput></screen>
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[54ff0b9] | 68 |
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| 69 | <para>If all is well, Grub will have reported finding its files in
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[e3a72b1] | 70 | <filename>/boot/grub</filename>. That's all there is to it:</para>
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[54ff0b9] | 71 |
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[21ba4e3] | 72 | <screen><userinput>quit</userinput></screen>
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[54ff0b9] | 73 |
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[360e2c4] | 74 | <para>Now we need to create a "menu list" file, defining Grub's boot
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| 75 | menu:</para>
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[54ff0b9] | 76 |
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[21ba4e3] | 77 | <screen><userinput>cat > /boot/grub/menu.lst << "EOF"</userinput>
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[1561534] | 78 | # Begin /boot/grub/menu.lst
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| 79 |
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[54ff0b9] | 80 | # By default boot the first menu entry.
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[1561534] | 81 | default 0
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| 82 |
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[54ff0b9] | 83 | # Allow 30 seconds before booting the default.
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[1561534] | 84 | timeout 30
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| 85 |
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[54ff0b9] | 86 | # Use prettier colors.
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[1561534] | 87 | color green/black light-green/black
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| 88 |
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[54ff0b9] | 89 | # The first entry is for LFS.
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[821f799] | 90 | title LFS &milestone;
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[bc362d4] | 91 | root (hd0,3)
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[1969cea] | 92 | kernel --no-mem-option /boot/lfskernel root=/dev/hda4
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[21ba4e3] | 93 | <userinput>EOF</userinput></screen>
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[1561534] | 94 |
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[1969cea] | 95 | <note><para>By default, Grub will automatically pass a "mem=xxx" command line
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[d0a6c4c] | 96 | argument to the kernel. However, Grub occasionally gets the amount of memory
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| 97 | wrong which can lead to problems in some circumstances. It's best to disable
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| 98 | this functionality and let the kernel determine the amount of memory itself,
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| 99 | hence the use of the <emphasis>--no-mem-option</emphasis> above.</para></note>
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[1969cea] | 100 |
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[17476c5] | 101 | <para>You may want to add an entry for your host distribution. It might look
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[54ff0b9] | 102 | like this:</para>
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[1561534] | 103 |
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[21ba4e3] | 104 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
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[54ff0b9] | 105 | title Red Hat
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[bc362d4] | 106 | root (hd0,2)
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[1969cea] | 107 | kernel /boot/kernel-2.4.20 root=/dev/hda3
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[bc362d4] | 108 | initrd /boot/initrd-2.4.20
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[21ba4e3] | 109 | <userinput>EOF</userinput></screen>
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[1561534] | 110 |
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| 111 | <para>Also, if you happen to dual-boot Windows, the following entry should
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| 112 | allow booting it:</para>
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| 113 |
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[21ba4e3] | 114 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
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[bc362d4] | 115 | title Windows
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| 116 | rootnoverify (hd0,0)
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| 117 | chainloader +1
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[21ba4e3] | 118 | <userinput>EOF</userinput></screen>
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[1561534] | 119 |
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[90e3cb3] | 120 | <para>If <command>info grub</command> doesn't tell you all you want to
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[54ff0b9] | 121 | know, you can find more information regarding Grub on its website, located at:
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[5cd6caa] | 122 | <ulink url="http://www.gnu.org/software/grub/"/>.</para>
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[955533b] | 123 |
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| 124 | </sect1>
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| 125 |
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