Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 216 — #242
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8.5 Booting with LILO
The Linux boot loader LILO is suitable for installation in the MBR. LILO
has access to two real-mode hard disks and is able to find all the data it
needs from the raw hard drives without any partitioning data. Therefore,
operating systems can also be booted from the second hard disk. Unlike
with the DOS boot process, the entries in the partition table are ignored
when using LILO.
The main difference from the standard DOS boot process is the possibility
to load diverse installed operating systems when booting. After loading the
MBR into memory, LILO is started, allowing the user to select from the list
of preinstalled systems. At system start-up, it can load boot sectors from
partitions to boot an operating system from the respective partition or load
the Linux kernel and boot Linux. It also provides the important possibility
of passing a command to the kernel. For security reasons, some or all LILO
services can be protected with a password.
The LILO boot mechanism consists of the following components:
The LILO boot sector with the initial part (first stage) of the LILO code
that activates the actual LILO when the system is booted.
The LILO machine code, located in /boot/boot-menu.b.
A map file (/boot/map), where LILO enters the location of Linux ker-
nels and other data during its installation.
Optional: the message file /boot/message, which displays the graph-
ical boot menu from which the operating system can be selected.
The different Linux kernels and boot sectors LILO should offer.
Caution
Map File Deletion through Write Access
Any write access (even through file movements) to any of these
files corrupts the map file — unless LILO is updated (see Sec-
tion 8.5.3 on page 222). This is especially important when chang-
ing kernels.
Caution
216 8.5. Booting with LILO