From: "H. Peter Anvin" <hpa@zytor.com>
To: robert@schwebel.de
Cc: Linux Kernel List <linux-kernel@vger.kernel.org>,
Christer Weinigel <wingel@hog.ctrl-c.liu.se>,
Jason Sodergren <jason@mugwump.taiga.com>,
Anders Larsen <anders@alarsen.net>,
rkaiser@sysgo.de, "Theodore Ts'o" <tytso@mit.edu>
Subject: Re: [PATCH][RFC] AMD Elan patch
Date: Tue, 01 Jan 2002 13:49:34 -0800 [thread overview]
Message-ID: <3C322EEE.5040402@zytor.com> (raw)
In-Reply-To: <Pine.LNX.4.33.0112311900380.3056-100000@callisto.local>
Robert Schwebel wrote:
> diff -urN -X kernel-patches/dontdiff linux-2.4.17/arch/i386/boot/setup.S linux-2.4.17-rs/arch/i386/boot/setup.S
> --- linux-2.4.17/arch/i386/boot/setup.S Fri Nov 9 22:58:02 2001
> +++ linux-2.4.17-rs/arch/i386/boot/setup.S Mon Dec 31 17:20:17 2001
> @@ -42,6 +42,9 @@
> * if CX/DX have been changed in the e801 call and if so use AX/BX .
> * Michael Miller, April 2001 <michaelm@mjmm.org>
> *
> + * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
> + * by Robert Schwebel, December 2001 <robert@schwebel.de>
> + *
> */
>
> #include <linux/config.h>
> @@ -646,7 +649,14 @@
> #
> # Enable A20. This is at the very best an annoying procedure.
> # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
> +# AMD Elan bug fix by Robert Schwebel.
> #
> +
> +#if defined(CONFIG_MELAN)
> + inb $0xee, %al # reading 0xee enables A20
> + jmp a20_done
> +#endif
> +
>
Do you have documentation which verifies that A20 is enabled by the time
the IN instruction returns? If not, you probably don't want to jump to
a20_done, but rather fall into a loop like the following:
#if defined(CONFIG_MELAN)
inb $0xee, %al
a20_elan_wait:
call a20_test
jz a20_elan_wait
jmp a20_done
#endif
Furthermore, I would still like to argue that this does not belong into
"processor type and features", because all of these are *chipset*
issues; in fact, in this particular case you're more than anything
working around a BIOS bug (not having INT 15h AX=2401h do the right thing).
I'm also very uncomfortable with putting this where you do; I think it
should be put before a20_kbc instead. If the BIOS is implemented
correctly, it should be used.
-hpa
next prev parent reply other threads:[~2002-01-01 22:04 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-12-21 21:26 AMD SC410 boot problems with recent kernels Robert Schwebel
2001-12-21 22:09 ` H. Peter Anvin
2001-12-22 16:13 ` Robert Schwebel
2001-12-23 1:44 ` H. Peter Anvin
2001-12-23 9:45 ` Robert Schwebel
2001-12-23 10:19 ` H. Peter Anvin
2001-12-23 13:16 ` Christer Weinigel
2001-12-23 20:02 ` H. Peter Anvin
2001-12-30 22:02 ` Robert Schwebel
2001-12-30 23:15 ` H. Peter Anvin
2002-01-01 12:30 ` [PATCH][RFC] AMD Elan patch Robert Schwebel
2002-01-01 21:49 ` H. Peter Anvin [this message]
2002-01-01 23:27 ` Robert Schwebel
2002-01-01 23:38 ` H. Peter Anvin
2002-01-02 0:05 ` Dave Jones
2002-01-02 0:45 ` H. Peter Anvin
2002-01-02 13:49 ` Robert Schwebel
2002-01-02 14:03 ` Dave Jones
2002-01-02 16:10 ` Alan Cox
2002-01-02 22:40 ` H. Peter Anvin
2002-01-02 23:10 ` Alan Cox
2002-01-02 23:02 ` H. Peter Anvin
2002-01-02 23:50 ` Alan Cox
2002-01-03 9:04 ` Robert Schwebel
2002-01-02 23:56 ` Robert Kaiser
2002-01-03 0:10 ` Alan Cox
2002-01-03 8:52 ` Robert Schwebel
2002-01-02 16:06 ` Alan Cox
2002-01-02 16:56 ` Robert Schwebel
2002-01-02 17:26 ` Robert Schwebel
2002-01-02 23:06 ` Peter Wächtler
2002-01-02 23:21 ` H. Peter Anvin
2002-01-02 1:07 ` [RFC] Embedded X86 systems Was: " Christer Weinigel
2002-01-02 8:45 ` Alan Cox
2002-01-02 9:05 ` Christer Weinigel
2002-01-02 9:18 ` Alan Cox
2002-01-05 12:23 ` Eric W. Biederman
2002-01-02 0:06 ` Christer Weinigel
2002-01-02 0:48 ` H. Peter Anvin
2002-01-02 1:10 ` Christer Weinigel
2002-01-02 13:58 ` Robert Schwebel
2002-01-02 20:47 ` Christer Weinigel
2002-01-02 13:55 ` Robert Schwebel
2002-01-02 15:54 ` Robert Schwebel
2002-01-11 9:38 ` [PATCH] " Robert Schwebel
2002-01-21 7:28 ` New version of " Robert Schwebel
2002-01-21 20:44 ` Marcelo Tosatti
2002-01-24 8:09 ` Robert Schwebel
2002-01-24 8:39 ` Robert Schwebel
2002-01-23 10:28 ` [PATCH] " Robert Schwebel
2002-01-23 21:30 ` Marcelo Tosatti
2002-01-22 14:47 ` [PATCH][RFC] " Robert Schwebel
2002-01-22 18:01 ` Dave Jones
2002-01-22 22:55 ` New version of AMD Elan patch available Robert Schwebel
2002-02-01 22:01 ` Robert Schwebel
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