Subject: Re: First stage boot trouble
To: NetBSD 386 Port <port-i386@NetBSD.ORG>
From: Hellmuth Michaelis <>
List: port-i386
Date: 03/18/1995 11:53:50
>From the keyboard of Jon Cargille:
> I'm having a problem with the first-stage boot in NetBSD-1.0.
> I was installing on a DECpc (XL 950 or somesuch); it's a pentium with
> an NCR 53c810 SCSI controller.
> The installation went fine, with only one problem; after the install
> was done, the machine won't boot from the hard-drive (it prints "Read
> error" and stops).
> Has anyone seen this problem before?  Any suggestions?

Yes, i saw this on some machines over here. I bet, the BIOS boot loader does
not return 0x80 in %dl when returning. The routine in question is start.S,
have a look at the beginning and you'll see what i mean.

One can solve this problem in 2 ways, one - write your own start.S for hard
disk boot (did this several times) and try to get it into the release (failed
on that ;-) or patch the BIOS to return the correct values for the INT 19
call. The latter was my final solution, i used a product called "Sourcer"
to disassemble my BIOS, finding the vendor had put some code at the end of
the INT 19 routine which destroyed %dl, patched that a bit to preserve %dl
and since then i'm able to boot from harddisk.

Hellmuth Michaelis        GFKT HCS Computertechnik GmbH        Hamburg, Europe
                     We all live in a yellow subroutine, yellow subroutine ...