Mark's Mega Multi-Boot Computer

After I started going to computer conferences, I realized I needed to be able to demonstrate Linux working with other operating systems as well as different distributions of Linux. Having one computer for each operating system seemed a bit much, so it became important to have a multi-boot computer to reduce the number of computers I would need. The goal was to put several distributions of Linux, along with other operating systems, onto the computer and be able to choose which operating system I wanted when I turned on the computer. The other operating systems were Windows 98, Windows NT, DOS and FreeBSD.

The computer was originally configured on an IDE system as follows:

The goal was to install more distributions of Linux and FreeBSD onto this computer. The problem was, all the disk space was used up. It was going to be hard to add more systems. A crazy solution had to be used, and this was where the beauty of Linux shone forth.

When the kernel for Linux starts, it doesn't have to reside on the same partition it will use for the “root” partition. The root partition for Linux is just like the root partition for UNIX systems: it contains all files and directories for the operating system to use after the kernel gets started. That is, the kernel can reside on a different partition than the one used for its files and directories after it starts.

So, put every non-Linux operating system on the first hard drive, as well as one small Linux installation. Then, install all other distributions of Linux onto a second hard drive. The small Linux installation on the first hard drive will contain the kernels for each of the Linux installations (including its own) that reside on the second hard drive. In addition, the small installation on the first hard drive will configure LILO, so that you can choose which version of Linux you want (off of the second hard drive) when the computer starts. The trick is, LILO will be configured to grab a kernel from the small installation on the first hard drive, then switch to the second hard drive and use the appropriate partition for that kernel.

In order to install FreeBSD and a small Linux installation on the first hard drive, both the original swap and Linux partition on the first hard drive must be deleted. In place of the swap partition, install a 100MB installation of Red Hat. In place of the original Linux partition, install FreeBSD. Now the configuration should look like this:

Listing 1 is the configuration of LILO in /etc/lilo.conf within the Linux partition.

Listing 1

Now, two steps are needed to install the rest of the Linux distributions on the second hard drive. First, all Linux distributions need to be installed without modifying how the computer boots up. The partition table on the second hard drive is set up as shown below. My second hard drive was an IDE hard drive set to be the master on the secondary IDE channel (which becomes “/dev/hdc” in Linux).

After each of these Linux distributions is installed on the second hard drive, the hardest part is setting it up so that any of these operating systems or Linux distributions can be chosen at boot time. Next, do the following:

Listing 2

Because LILO was installed, when the computer reboots the LILO prompt will come up. From here, pressing the TAB key gives a list of the various options from which to choose. Typing in one of the following will start the corresponding operating system: “linux”, “linuxkernels”, “MicroSoft”, “FreeBSD”, “Debian”, “Slackware”, “Caldera”, “SUSE” or “Mandrake”. Choosing nothing would mean that the first option “linux” would be chosen. Also, if “MicroSoft” is chosen, another menu will pop up which will let you choose “Windows98” or “WindowsNT”. This other menu is the NT Boot Loader.