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Date: Wed, 06 Dec 2000 13:43:08 +0100
From: Giacomo Catenazzi <cate@student.ethz.ch>
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To: "H. Peter Anvin" <hpa@transmeta.com>
CC: Linus Torvalds <torvalds@transmeta.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alan Cox <alan@redhat.com>
Subject: Re: That horrible hack from hell called A20
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"H. Peter Anvin" wrote:
> 
> 
> Good question.  The whole thing makes me nervous... in fact, perhaps we
> should really consider using the BIOS INT 15h interrupt to enter
> protected mode?
> 

Maybe it is better to try with INT15 AX=2400 (Enable A20 gate). 

INT 15-2400 enable A20
INT 15-2401 disable A20
INT 15-2402 query status A20
INT 15-2403 query A20 support (kdb or port 92)

IBM classifies these functions as optional, but it is enabled on a lot
of
new BIOS, no know conflicts, thus we can call this function to enable
A20,
check the result and only after failure we can try the old methods.


	giacomo
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