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2. Background Information and Standard Installation

When Lilo boots the system, it can only load data sectors that can be accessed by the bios. Any pathname you put in /etc/lilo.conf is resolved at installation time (when you invoke lilo); this is when the program builds any table listing which sectors are used by the files. As a consequence, the files must live in a partition that can be accessed by the BIOS; moreover, you must reinstall the loader (i.e., you must reinvoke lilo) any time you modify the files. Whenever you recompile your kernel and overwrite your old image you must reinstall Lilo).

2.1 Where Should I Install Lilo?

The boot = directive in /etc/lilo.conf tells Lilo where it should put its primary boot loader. In general, you can either specify the master boot sector (/dev/hda) or the root partition of your Linux installation (is usually is /dev/hda1 or /dev/hda2).

If you have another operating system installed in your hard drive, you'd better install Lilo to the root partition. In this case, you must mark the partition as ``bootable'' (use the ``a'' command of fdisk or the ``b'' command of cfdisk. If you don't overwrite the master boot sector you'll find it easier to uninstall Linux and Lilo if needed.

2.2 How Should I Configure my IDE Hard Drives?

I personally don't use LBA or LARGE settings in the BIOS (but I only run Linux); they are horrible kludges forced on by design deficiencies in the PC world. This requires that the kernel lives in the first 1024 cylinders, but this is not a problem as long as you partition your hard drives and keep root small (as you should do anyways).

If your hard disk already carries another operating system, you won't be able to modify the BIOS settings, or the old system won't work any more. All recent Lilo distribution are able to deal with LBA and LARGE disk settings.

If you have more than one hard disk and some of them are only used by Linux, but are not used in booting, you can tell your BIOS that they are not installed. Your system will boot more quickly and Linux will autodetect all the disk in no time. I often connect extra disks to my system, but I never touch the BIOS configuration.

2.3 How Can I Interact at Boot Time?

When you see the Lilo prompt, you can hit the <Tab> key to show the list of possible choices. If Lilo is not configured to be interactive, press and hold the <Alt> or <Shift> key before the ``LILO'' message appears.

If you choose to boot a Linux kernel, you can add command-line arguments after the name of the system you choose. The kernel accepts many command-line arguments, and this is not the place to list them all. A few of them are particularly important, in my opinion:

2.4 How Can I Uninstall Lilo?

When Lilo overwrites a boot sector, it saves a backup copy in /boot/boot.xxyy, where xxyy are the major and minor numbers of the device, in hex. You can see the major and minor numbers of your disk or partition by running ``ls -l /dev/device''. For example, the first sector of /dev/hda (major 3, minor 0) will be saved in /boot/boot.0300, installing Lilo on /dev/fd0 creates /boot/boot.0200 and installing on /dev/sdb3 (major 8, minor 19) creates /boot/boot.0813. Note that Lilo won't create the file if there is already one; you don't need to care about the backup copy whenever you reinstall Lilo (for example, after recompiling your kernel).

If you ever need to uninstall Lilo (for example, in the unfortunate case you need to uninstall Linux), you just need to restore the original boot sector. If Lilo is installed in /dev/hda, just do ``dd if=/boot/boot.0300 of=/dev/hda bs=446 count=1'' (I personally just do ``cat /boot/boot.0300 > /dev/hda'', but this is not safe, as this will restore the original partition table as well, which you might have modified in the meanwhile). This command is much easier to run than trying ``fdisk /mbr'' from a DOS shell: it allows you to cleanly remove Linux from a disk without ever booting anything else. After removing Lilo remember to run Linux' fdisk to destroy any Linux partition (DOS' fdisk is unable to remove non-dos partitions).

If you installed Lilo on your root partition (e.g., /dev/hda2), nothing special needs to be done to uninstall Lilo. Just run Linux' fdisk to remove Linux partitions from the partition table. You must also mark the DOS partition as bootable.


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