Uninstalling/updating Lilo

Bill's LFS Login lfsbill at wlmcs.com
Mon Sep 8 09:15:52 PDT 2003

On Mon, 8 Sep 2003, Erik Postma wrote:

> On Mon, 8 Sep 2003 15:30:01 +0100, "Declan. Moriarty"
> <declan.moriarty at ntlworld.ie> wrote:
> > On Sun, Sep 07, 2003 at 07:40:23AM -0400, Bill's LFS Login enlightened
> > us thusly
> > >
> > ><snip>

> If I understand matters correctly (which I may not), then LILO makes the
> BIOS search for the kernels at boot time, right? What happens if you copy

No. Lilo does "pre-analysis" at boot time and installs boot blocks with
locations of the components it needs as offsets from the start of the
partitions that are the targets. BIOS only provides a device assignment
to Lilo, which may be reassigned, and Lilo needs to know what this
device assignment will be at boot time because it *does* use BIOS calls
to access the first blocks of the secondary loader, IIRC. So BIOS
provides only two services: assigns the booted drive to device 0x80 and
provides "system calls", used by Lilo, that can access the device.

> the kernel from hdd to your Mandrake or old LFS /boot, update lilo.conf
> to register that kernel (and of course still root=hdd) and rerun lilo?

Should have no effect. Lilo only determines *locations* and updates boot
blocks. What's in the kernel will have no effect.

> On a slightly different and possibly more destructive train of thought,
> what happens if you switch hdd and hdb? (So, open the box and switch the
> flatcables.) I think I remember reading somewhere that in some situations,

If the boot blocks were installed expecting what was hdb to be the boot
device, *and* if those same blocks were installed on hdd, which they
were not AFAICT, that would probably work. Of course, adjustments to
fstab and other things might be needed to make sure the kernel found
components that matched what the kernel was expecting to see.

> the combination LILO/BIOS sometimes has trouble finding disks on other
> than the primary IDE cable thingy, what's it called? I mean, like hda is
> primary master, hdb is primary slave, hdc is secondary master etc. If this
> is the problem though, then I guess it should be solved by cp'ing the
> kernel too, though.

IIRC, this is only for certain buggy BIOS? Normal newer BIOSs shouldbe
able to boot any drive and reassign it device to 0x80. Older BIOS did
not have these capabilities and a cable switch was need to get secondary
drives to boot. But Lilo would still need to be told about the switch
*or* you need to do some really fancy "dd'ing" to copy some selected
stuff from one drive to the other. best chance of success would be if
the drive had identical geometry and all partitioning at the same
locations and both /boot directories were on their own partitions and
had been created from emptry with no updates (other than Lilo making
the backup boot blocks). Else, you are *doomed*.

> HTH,

Bill Maltby
lfsbill at wlmcs.com

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