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From: Terry Lambert <terry@lambert.org>
Message-Id: <199510272015.NAA23839@phaeton.artisoft.com>
Subject: Re: boot disk....
To: bde@zeta.org.au (Bruce Evans)
Date: Fri, 27 Oct 1995 13:15:53 -0700 (MST)
Cc: msmith@atrad.adelaide.edu.au, terry@lambert.org, hackers@freebsd.org,
        lenzi@cwbone.bsi.com.br
In-Reply-To: <199510271940.FAA25718@godzilla.zeta.org.au> from "Bruce Evans" at Oct 28, 95 05:40:54 am
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> >Stage 2 boostrap ...
> >... should perform MBR fixup to
> >guarantee that the absolute offset field in the MBR matches the c/h/s 
> >values for the slice under the BIOS geometry.
> 
> Only for its own benefit.  Drivers don't want to know about yet another
> translation.

If this is there, then there is NO SUCH THING AS TRANSLATION from the
kernel perspecitve.  The kernel ignores the C/H/S values, using the 32
bit sector offsets instead (which are now guaranteed to be valid).

Almost all translation problems bite the dust.  The exception is for
non-linear translation (BIOS-based sector sparing, etc.), and then
you are screwed on a shared disk in any case unless you can turn it
off.  You are also screwed unless the disk is used as a naked BSD disk
without a DOS partition table/MBR.  It works with the BIOS boot code
because the cylinder offset on a naked partition is invariant under
translation.

> >It should also be buildable
> >as a DOS program, to allow it to work with Ontrack's Disk Mangler.  The
> 
> Nothing should require DOS utilitites to build.

Agree.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.