2.8. LILO

2.8.1. LILO and the x86 Boot Process

This section discusses in detail the specific role LILO plays when booting an x86 system. For a detailed look at the overall boot process, see Section 1.2 A Detailed Look at the Boot Process.

LILO loads itself into memory almost identically to GRUB, except it is only a two stage loader.

1. The Stage 1 or primary boot loader is read into memory by the BIOS from the MBR[1]. The primary boot loader exists on less than 512 bytes of disk space within the MBR. It only loads the Stage 2 boot loader and passes disk geometry information to it.

2. The Stage 2 or secondary boot loader is read into memory. The secondary boot loader displays the Red Hat Linux initial screen. This screen allows you to select which operating system or Linux kernel to boot.

3. The Stage 2 boot loader reads the operating system or kernel and initrd into memory. Once LILO determines which operating system to start, it loads it into memory and hands control of the machine to that operating system.

Linux is the only operating system installed, linux will be the only available option. If the system has multiple processors there will be a linux-up option for the single processor kernel and a linux option for the multiple processor (SMP) kernel. If LILO is configured to boot other operating systems, those boot entries also appear on this screen.

The arrow keys allow a user to highlight the desired operating system and the [Enter] key begins the boot process.

To access a boot: prompt, press [Ctrl]-[X].

2.8.2. LILO versus GRUB

In general, LILO works similarly to GRUB except for three major differences:

• It has no interactive command interface.

• It stores information about the location of the kernel or other operating system it is to load on the MBR.

• It cannot read ext2 partitions.

The first point means the command prompt for LILO is not interactive and only allows one command with arguments.

/sbin/lilo -v -v

to its command line interface where the user can boot the system manually.

	Tip
	If upgrading the kernel using the Red Hat Update Agent, the MBR will be updated automatically. More information about RHN is available online at the following URL: https://rhn.redhat.com