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An in-depth look at LILO

Linux has the capability to support a maximum of four primary partitions. If additional partitions are required, one of the partitions can be made an extended partition where additional logical partitions created. One important point to note is that the partition tables of some logical partitions are not accessible as the first block of some devices, while in the main partition table all boot sectors and partitions tables of the extended partitions are. Partition tables are generally stored in the boot sector of the partition and normally only the partition boot sector of the entire disk is usable as the boot sector. This is called the Master Boot Record (MBR).

LILO can be made use of in the following instances.

1. Writing to the boot sector of the first hard disk.

2. Boot Sector of a floppy disk.

3. Boot sector of a primary Linux file system partition on the first hard disk.

LILO can't be made use of in the following instances.

1. Writing it to a SWAP partition.

2. Boot sector of a LOGICAL partition in an extended partition.

Various programs that make up your Boot Loader

Let's now look at the various programs that are a part of the LILO installation.

The MAP installer: This program puts all the files belonging to LILO in the appropriate places and also to record the location of information, which will be needed by LILO during boot-up. This program would be /sbin/lilo and has to be run every time there is a change in the configuration file or if there is a new kernel.

/boot/*.*: Various other files required by LILO during the booting sequence are stored in the /boot directory. Some of the more important files are the boot loader and the map file. Apart from these you are likely to find the stock kernel here. The map file is an important file where the map installer records the location of the new kernel.

Boot Loader: The boot loader is by far the most important component. The boot loader is loaded into memory by the BIOS. This then loads the kernel or possibly the boot sector of other operating systems.

The boot sector containing the first part of the boot loader is loaded into memory which then loads the second part of the boot loader which is generally stored in the file /boot/boot.b. The boot loader then starts the kernel.