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Re: install-mbr vs lilo



Oswald Buddenhagen wrote:

Can anyone explain to me the difference between install-mbr and lilo?

the layout of a (pc) hard drive:

+-----------+-----------+-----------------------+--
| partition | few       | first partition       | second partition
| table     | wasted    | +-----------+-------+ | +
| + mbr     | kilobytes | |boot sector|data...| | |boot .......
| sector    |           | +-----------+-------+ | +
+-----------+-----------+-----------------------+--

the mbr is run by the bios.
the normal (i.e., dos-compatible) mbr now detects the active partition
from the partition table (which is in the same sector). it just loads
the boot sector (i.e. the first sector of the given partition) and
executes it. the boot sector usually contains the bootstrap code of the
operating system.
install-mbr installs such dos-compatible mbr with additional features
like inteactive partition selection and floppy boot.

with lilo you have two choices: 1) install it into the boot sector of some partition. then it only gets
activated, if this partition is the active one.
2) install it into the mbr. then the normal active partition selection
gets overriden and lilo.conf says, which boot options you have.

usual problem: the "LI [hang]" or "L 01 01 ..." problem: lilo cannot find it's stage 2(?) loader.
as a single sector is too small for an entire boot loader like lilo,
the lilo boot sector/mbr only takes care of loading the main binary, which
then does all the work. this main binary usually lives in /boot/boot.b.
problems usually arise due to lilo's misconception of the drive(s) it is operating on. possibly it's the drive's geometry.
in your case some other problem may arise: lilo has a different idea about
the order of the disks than the bios. lilo normally assumes, that ide disks
are detected before the scsi disks. however, on some systems this is not
true. in this case you must insert something like this in your lilo.conf:

disk = /dev/sda
  bios = 0x80

this would force lilo into believing, that the first scsi disk is really the first disk in the system.

hth
good luck!


I don't think I every said "Thank you" for this. This was a great explanation! I appreciate it very much!




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