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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [bug, 2.5.29, IDE] partition table corruption?
Date: 8 Aug 2002 23:06:43 -0700
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References: <UTC200208081822.g78IM2r23833.aeb@smtp.cwi.nl> <3.0.5.32.20020808153603.01476050@pop-server.san.rr.com>
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Followup to:  <3.0.5.32.20020808153603.01476050@pop-server.san.rr.com>
By author:    John Coffman <johninsd@san.rr.com>
In newsgroup: linux.dev.kernel
> 
> The lilo boot loader must use the BIOS as its disk driver to access the
> disk at boot time.  It may be directed to use one of three addressing modes:
> 
>   geometric - use int 13h, fn 2 (CHS read)
>   linear - convert 24-bit disk address to CHS, use int 13h, fn 2 as above.
>   lba32 - 32-bit disk addresses; IF AVAILABLE, use int 13h, fn 42h (EDD
> packet call) to read disk; else convert disk address to CHS, use int 13h,
> fn 2 as above.
> 
> All CHS addressing is subject to the 1024 cylinder limit.  If a 'linear' or
> 'lba32' address is converted to CHS, the head/sector information need for
> the conversion is obtained with int 13h, fn 8 (Get drive parameters).
> 

Why support geometric at all?  Either "linear" or "lba32" should work
on all systems (otherwise (Win)DOS won't work either.)

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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