7.3. Map Files, GRUB, and LILO

The main obstacle for booting an operating system is that the kernel is usually a file within a file system on a partition on a disk. These concepts are unknown to the BIOS. To circumvent this, maps and map files were introduced. These maps simply note the physical block numbers on the disk that comprise the logical files. When such a map is processed, the BIOS loads all the physical blocks in sequence as noted in the map, building the logical file in memory.

In contrast to LILO, which relies entirely on maps, GRUB tries to gain independence from the fixed maps at an early stage. GRUB achieves this by means of the file system code, which enables access to files by way of the path specification instead of the block numbers.

[Important]Boot Loader Selection

If you update from a previous version of SUSE LINUX in which LILO was the boot manager, the new system continues to use LILO. If you install SUSE LINUX from scratch, the system uses GRUB unless the root partition is installed on a RAID system of the following types:

  • CPU-controlled RAID controllers, such as many Promise and Highpoint controllers

  • software RAID

  • LVM

For information about the installation of LILO, search for the keyword “LILO” in the Support Database (http://portal.suse.de/sdb/en/index.html).