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From: Andries Brouwer <aeb@veritas.com>
To: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
Subject: Re: KERNEL BUG: console not working in linux
Date: Tue, 28 Nov 2000 02:36:52 +0100	[thread overview]
Message-ID: <20001128023652.A9368@veritas.com> (raw)
In-Reply-To: <E140Pc3-0003AI-00@the-village.bc.nu> <200011271849.eARInfc255418@saturn.cs.uml.edu> <8vubeq$r5r$1@cesium.transmeta.com> <20001127202738.A25168@vana.vc.cvut.cz>
In-Reply-To: <20001127202738.A25168@vana.vc.cvut.cz>; from vandrove@vc.cvut.cz on Mon, Nov 27, 2000 at 08:27:38PM +0100

On Mon, Nov 27, 2000 at 08:27:38PM +0100, Petr Vandrovec wrote:

>   could original complainer (and peoples with AMD SC*) test following
> patch? It just does nothing in case that A20 enabled bit is already
> set - such as in case when there is nobody listening on 0x92 and
> so inb returns 0xFF... (patch is for 2.4.0-test11) 
> 
> --- linux/arch/i386/boot/setup.S.orig	Mon Oct 30 23:44:29 2000
> +++ linux/arch/i386/boot/setup.S	Mon Nov 27 20:22:04 2000
> @@ -647,8 +647,11 @@
>  #	Brown from Linux 2.2
>  #
>  	inb	$0x92, %al			# 
> +	testb   $02, %al
> +	jnz     no92
>  	orb	$02, %al			# "fast A20" version
>  	outb	%al, $0x92			# some chips have only this
> +no92:
>  

What about adding an additional

	andb	$0xfe, %al

in front of the outb?
If I understand things correctly, bit 0 of 0x92 is write-only
on some hardware, and writing 1 to it causes a reset, so we
never want that.

Andries
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  reply	other threads:[~2000-11-28  2:07 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-11-26 21:28 KERNEL BUG: console not working in linux Gianluca Anzolin
2000-11-26 23:53 ` Jorge Nerin
2000-11-27 14:05 ` Gianluca Anzolin
2000-11-27 14:50   ` Alan Cox
2000-11-27 18:49     ` Albert D. Cahalan
2000-11-27 19:08       ` H. Peter Anvin
2000-11-27 19:27         ` Petr Vandrovec
2000-11-28  1:36           ` Andries Brouwer [this message]
2000-11-28  1:40             ` H. Peter Anvin
2000-11-28  3:14               ` Andries Brouwer
2000-11-28  3:23                 ` H. Peter Anvin
2000-11-27 19:52         ` Albert D. Cahalan
2000-11-27 19:59           ` H. Peter Anvin
2000-11-28  0:16         ` Gianluca Anzolin
     [not found]           ` <3A22EF3D.B97A0965@transmeta.com>
2000-11-28  9:33             ` Gianluca Anzolin
2000-11-28 18:14               ` H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2000-11-28  4:09 Dunlap, Randy

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