Linux is a freely-distributable implementation of Unix for inexpensive personal machines (it was developed on 386s, and now supports 486, 586, Pentium, PowerPC, Sun Sparc, ARM and DEC Alpha hardware, and even the IBM System 390 mainframe!). It supports a wide range of software, including X Windows, Emacs, TCP/IP networking (including SLIP), and many applications.

This guide attempts to show how the writer used LILO to successfully launch two different Linux distributions on one computer, which itself is crippled by the 1024 cylinder limit

The first port of call for any Linux user should always be their own computer. On any terminal/console, do

[user@machine ~/dir]$ man lilo
[user@machine ~/dir]$ man lilo.conf 
                

Briefly, the procedure is as follows:

Install your chosen distribution. I would suggest keeping the installation small at first, particularly if you are confident on the command line. Don't worry at this stage with X, KDE and Gnome, just get the basic Linux architecture in place.

The three most important steps, however, are to

Using whatever method applies in your case, start your second installation. You shouldn't need to do any hard-disk repartitioning at this stage, but keep your table to hand.

Keep especial note of the filesystem your second distribution will be using, be it ext2, ext3, resierfs or some other system. The filesystem must be usable by your First Distribution. This shouldn't cause any problems with different flavors of Linux, but may be an issue for some users with special requirements. Make certain to note the filesystems on your table.

If the distribution offers it, choose LILO as your boot-loader. This makes things easier later on. If LILO isn't offered, then proceed, ensuring that the bootloader is installed on the MBR. Again, I would recommend that a minimalist distribution should be used, I just installed Debian's base-system components, nothing else. Other than those points, just proceed normally - have coffee, cake, whatever. Once it is complete, remove all installation media from your computer, and proceed to the next phase. I'd recommend completing the project before loading the Second Distro - the first boot is often used by distributions for a lot of configuration stuff, and that can wait.

Insert your First Distribution boot disk - in my case, Slackware, and get the system back up and running. All should work well if you've come this far. Time for the hard part.

This is something that once terrified me, but I now know that it isn't too bad. Log in to your First Distro as root. Take a moment before all the editing and do

[root@machine ~/dir]# mkdir /mnt/other_root

[root@machine ~/dir]# mkdir /mnt/other_boot
[root@machine ~/dir]# 

Then fire up an editor. I would recommend pico or nano, but feel free to use whatever is available and you are comfortable with. vi or emacs are the popular editors, but a little too dramatic for our purposes.

In any event, load the file /etc/fstab into the editor and have a good look. The format of the file is somewhat similar to the output from df

/dev/hda9        swap             swap        defaults         0   0
/dev/hda11       /                reiserfs    defaults         1   1
/dev/hda2        /boot            ext2        defaults         1   2
/dev/hda10       /home            reiserfs    defaults         1   2
/dev/cdrom       /mnt/cdrom       iso9660     noauto,owner,ro  0   0
/dev/fd0         /mnt/floppy      auto        noauto,owner     0   0
/dev/sr0     	 /mnt/scd         auto        noauto,owner,ro  0   0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0

Time to get your all important table back out. Create some extra lines in /etc/fstab

/dev/hda1   /mnt/other_boot ext3    defaults        1 2
/dev/hda5   /mnt/other_root ext3    defaults        1 2

Ensure that the entries under type reflect the decisions you made about filesystem when you were installing your second distribution - ext2 or resiserfs or, gods forbid, minix.

When done, exit your editor in the usual manner and issue the Command

[root@machine ~/dir]# mount /mnt/other_boot
[root@machine ~/dir]# mount /mnt/other_root
[root@machine ~/dir]#

With any luck at all it'll work swimmingly and you will be able to poke around in the other distribution to your curiosities' pleasure. Please make sure not to break anything - look, don't touch!

Back to business - what you are looking for is the contents of the /mnt/other_root/etc/lilo.conf file. I would suggest that you

[root@machine ~/dir]# cat /mnt/other_root/etc/lilo.conf | less

on a virtual console (or xterm) other than your main console. [Note: Normally, to use a different virtual console, press Alt-2 and login as normal.] This allows you to inspect it separately to the /etc/lilo.conf of your first distribution. Find the point in the output where the Linux stanza is present, often it looks as follows

image=/boot/vmlinuz
  label=Linux
  root=/dev/hda5

There may be some other information there, read man lilo or man lilo.conf to get the specific details. The information you need is (for example):

Keep this information close at hand before venturing to the next step.

While logged in as root, do

[root@machine ~/dir]# cp /etc/lilo.conf ~/oldlilo.conf
[root@machine ~/dir]# pico /etc/lilo.conf
[root@machine ~/dir]#

The first step copies your lilo.conf to your root home directory. The second opens your favourite editor to do the actual work. Always back-up, even in this most rudimentary fashion, when making changes as root

In your /etc/lilo.conf insert the relevant lines from the other distro's lilo.conf taking care to make adjustments to reflect the fact that their locations are now dependent on the First Distribution, not their own! Where the line used to read image=/vmlinuz, it should now read image=/mnt/other-boot/vmlinuz. Also adjust the label to something more intelligent. Your /etc/lilo.conf should be something like:

# Start LILO global section
boot = /dev/hda   # or your root partition
message = /boot/boot_message.txt
prompt
timeout = 1200     # delay, in tenth of a second (so you can interact)
#linear           # try "linear" in case of geometry problems.

image = /boot/vmlinuz   # your First Distro Kernel file
  root = /dev/hda11     # your First Distro root partition
  label = Slackware 9.1 # or whatever name you want for First Distro
  read-only             # mount root read-only - safer!

image = /mnt/other-boot/vmlinuz  # adjusted kernel line from /mnt/other-boot/etc/lilo.conf
  root = /dev/hda5               # as per /mnt/other-boot/etc/lilo.conf
  label = Debian 'Sarge'         # whatever name for your Second Distro
  read-only                      # mount root read-only - safer!

This action may seem unusual to some people, given that the mount-point /mnt/other-root is only useful within the First Distro - Slackware in my case. This, however, is the darkest of secrets about LILO - it only reads the file /etc/lilo.conf once, and once only. That time is when you run /sbin/lilo.

The file /etc/lilo.conf is a set of instructions to LILO to aid it in creating a boot-structure for your disk. It has no other purpose in life. Once you have run /sbin/lilo you can delete the file for all that the system cares. You shouldn't, of course, because you may wnat to make adjustments later, like varying the vga codes or some other topic outside the scope of this document. But, you could!

Nearly there now. Save and exit in the usual fashion. Then take a deep breath, then issue

[root@machine ~/dir]# /sbin/lilo
Wrote Slackware 9.1*
Wrote Debian 'Sarge'
[root@machine ~/dir]#

The asterisk * is just telling you that Slackware is the default option. That should all have worked nicely.

Whatever. Remove all floppies, CD-ROMs and so forth. Shut down your First Distribution in the proper manner. Light some candles, pray, do whatever calms those nerves and calls upon your own $DEITY for assistance.

Turn on your computer. Rejoice as the LILO menu comes up on screen, offerring you the choice of booting into either of your favoured distributions. You may now look forward to a happy and restful time using your computer.

Put your boot disk for your distributions someplace safe. You never know when you may need them again.

No animals were harmed in the making of this HOWTO