1 | <sect1 id="ch08-grub">
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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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5 | <para>Your shiny new LFS system is almost complete. One of the last things to
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6 | do is ensure you can boot it. The instructions below apply only to computers
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7 | of IA-32 architecture, i.e. mainstream PC's. Information on "boot loading" for
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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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28 | <userinput>grub</userinput> shell:</para>
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29 |
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30 | <screen><userinput>grub</userinput></screen>
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31 |
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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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40 |
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41 | <para>Using the above information, determine the appropriate designator for
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42 | your root partition. For the following example, we'll assume your root
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43 | partition is <filename>hda4</filename>.</para>
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44 |
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45 | <para>First, tell Grub where to search for its <filename>stage{1,2}</filename>
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46 | files -- you can use Tab everywhere to make Grub show the alternatives:</para>
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47 |
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48 | <screen><userinput>root (hd0,3)</userinput></screen>
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49 |
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50 | <!-- HACK - Force some whitespace to appease tidy -->
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51 | <literallayout></literallayout>
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52 |
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53 | <warning><para>The following command will overwrite your current boot loader.
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54 | Don't run the command if this is not what you want. For example, you may be
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55 | using a third party boot manager to manage your MBR (Master Boot Record). In
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56 | this scenario, it would probably make more sense to install Grub into the
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57 | "boot sector" of the LFS partition, in which case the command would become:
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58 | <userinput>setup (hd0,3)</userinput>.</para></warning>
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59 |
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60 | <!-- HACK - Force some whitespace to appease tidy -->
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61 | <literallayout></literallayout>
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62 |
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63 | <para>Then tell it to install itself into the MBR (Master Boot Record) of
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64 | <filename>hda</filename>:</para>
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65 |
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66 | <screen><userinput>setup (hd0)</userinput></screen>
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67 |
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68 | <para>If all is well, Grub will have reported finding its files in
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69 | <filename>/boot/grub</filename>. That's all there is to it:</para>
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70 |
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71 | <screen><userinput>quit</userinput></screen>
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72 |
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73 | <para>Now we need to create a "menu list" file, defining Grub's boot
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74 | menu:</para>
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75 |
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76 | <screen><userinput>cat > /boot/grub/menu.lst << "EOF"</userinput>
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77 | # Begin /boot/grub/menu.lst
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78 |
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79 | # By default boot the first menu entry.
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80 | default 0
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81 |
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82 | # Allow 30 seconds before booting the default.
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83 | timeout 30
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84 |
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85 | # Use prettier colors.
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86 | color green/black light-green/black
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87 |
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88 | # The first entry is for LFS.
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89 | title LFS &milestone;
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90 | root (hd0,3)
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91 | kernel /boot/lfskernel root=/dev/hda4 ro
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92 | <userinput>EOF</userinput></screen>
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93 |
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94 | <para>You may want to add an entry for your host distribution. It might look
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95 | like this:</para>
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96 |
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97 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
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98 | title Red Hat
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99 | root (hd0,2)
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100 | kernel /boot/kernel-2.4.20 root=/dev/hda3 ro
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101 | initrd /boot/initrd-2.4.20
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102 | <userinput>EOF</userinput></screen>
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103 |
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104 | <para>Also, if you happen to dual-boot Windows, the following entry should
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105 | allow booting it:</para>
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106 |
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107 | <screen><userinput>cat >> /boot/grub/menu.lst << "EOF"</userinput>
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108 | title Windows
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109 | rootnoverify (hd0,0)
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110 | chainloader +1
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111 | <userinput>EOF</userinput></screen>
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112 |
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113 | <para>If <userinput>info grub</userinput> doesn't tell you all you want to
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114 | know, you can find more information regarding Grub on its website, located at:
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115 | <ulink url="http://www.gnu.org/software/grub"/>.</para>
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116 |
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117 | </sect1>
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118 |
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