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Date: Fri, 7 Feb 1997 08:40:19 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199702062140.IAA05338@godzilla.zeta.org.au>
To: bde@zeta.org.au, terry@lambert.org
Subject: Re: DOS partition trouble
Cc: durham@w2xo.pgh.pa.us, hackers@FreeBSD.org
Sender: owner-hackers@FreeBSD.org
X-Loop: FreeBSD.org
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>> For SCSI disks with at least ncr controllers, this could be caused
>> a DOS partition that ends on a cylinder boundary and FreeBSD partition
>> that doesn't.  When you remove the DOS partition, the controller's BIOS
>> will have problems determining the disk geometry.
>
>What?  The BIOS examines the disk to get the geometry?
>
>How do you put something on the disk in the first place, then?

For disks with a nonexistent or empty partition table, the BIOS
chooses a default (one with <= 1024 cylinders if possible.  This is
always possible for disks with < 63*255*1024 sectors).

>I was under the impression that fictitious geometry was *always*
>an artifact of the BIOS's idea of geometry, not the oter way around.

That would usually fail for disks partitioned under another BIOS,
especially under an old BIOS with a limited number of defaults.

Bruce