Subject: Re: Boot Problems (fdisk / disklabel)
To: Greywolf <greywolf@starwolf.com>
From: David Laight <david@l8s.co.uk>
List: current-users
Date: 03/27/2002 20:13:30
On Sun, Mar 24, 2002 at 04:54:49PM -0800, Greywolf wrote:
> Now, this is interesting.
> 
> I am booting W2k and NetBSD on the same system, with NetBSD being the
> default (and listed at F1).  In order to boot from W2k, if I hit,
> simply, F6, nothing happens, and it hangs, and I have to restart.  If I
> hit F1, of course, it jumps into the NetBSD boot.
> 
> Now, if I hit F5, it re-prompts for NetBSD at F1, BUT if I *then* hit
> F6, it goes into the W2k bootloader.
> 
> So it does work, but in a most roundabout fashion.  Can anyone explain
> to me why I have to hit F5 to reload the partition boot map?

Let me get this straight:
1 - Bios loads netbsd bootselect from drive 80 sector 0
2 - bootselect code loads itself
3 - bootselect loads W2K boot code from drive 81 sector 0
4 - W2L boot code loads its pbr code from sector zero of ptn
5 - W2K runs.

but if you miss out stage 2 it doesn't work....

Guesses:
1) the w2k bootloader is confused by the contents of a register
   - unlikely that the second pass is any different!
2) the longer path gives time for the second disk to spin up
3) a bug in the bootsel code causes it to overwrite an
   important 'random' place on the first pass.

you could try my latest version of mbr_bootsel.S,
copy on www.l8s.co.uk then netbsd/mbr_bootsel* (source and binary)


	David

-- 
David Laight: david@l8s.co.uk