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To: Don Yuniskis <dgy@rtd.com>
cc: freebsd-hackers@freefall.FreeBSD.org (FreeBSD hackers)
Subject: Re: POST checksum hacking 
In-reply-to: Your message of "Wed, 03 Jan 1996 02:20:33 MST."
             <199601030920.CAA24493@seagull.rtd.com> 
Date: Wed, 03 Jan 1996 10:40:27 +0100
Message-ID: <918.820662027@critter.tfs.com>
From: Poul-Henning Kamp <phk@critter.tfs.com>
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> Greetings!
>    I have a few older (read: ancient!) Compaq systems I'd like to
> put FBSD on.  Unfortunately, Compaq (in their infinite wisdom -- NOT!)
> have fixed disk parameter tables in their BIOS.  So, regardless of
> the size of the (IDE) disk I might install, I am limited to
> whatever geometry Compaq has chosen to support.
>    I'd like to cut a new set of EPROMs with an altered disk table
> but the POST screams about bad checksums.  Anyone have a clue as
> to the algorithm employed and the location of the checksum image
> (before I start disassembling code)?

Don't even bother.  Just make sure that you use the same number of
heads and sectors as the bios, then adjust they cyls to the capacity
of the disk.

Many newer IDE disks will work with any geometry that is not bigger than
their capacity.

The root fs must be inside the bios geometry.

--
Poul-Henning Kamp           | phk@FreeBSD.ORG       FreeBSD Core-team.
http://www.freebsd.org/~phk | phk@login.dknet.dk    Private mailbox.
whois: [PHK]                | phk@ref.tfs.com       TRW Financial Systems, Inc.
Future will arrive by its own means, progress not so.