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From: David Wragg <dpw@doc.ic.ac.uk>
To: rct@gherkin.sa.wlk.com (Bob_Tracy),
	Joerg Diederich <dieder@ibr.cs.tu-bs.de>
Cc: davej@suse.de, linux-kernel@vger.kernel.org
Subject: Re: another Cyrix/mtrr problem?
Date: 14 Mar 2001 22:57:21 +0000	[thread overview]
Message-ID: <y7ru24wuffy.fsf@sytry.doc.ic.ac.uk> (raw)
In-Reply-To: <m14d1KU-0005khC@gherkin.sa.wlk.com>

rct@gherkin.sa.wlk.com (Bob_Tracy) writes:
> Unfortunately, when I execute
> 
> echo "base=0xd8000000 size=0x100000 type=write-combining" >| /proc/mtrr
> 
> I get a 2MB region instead of the 1MB region I expected...

Oops, it got broken by the MTRR >32-bit support in 2.4.0-testX.  The
patch below should fix it.

Joerg, I think this might well fix your Cyrix mtrr problem also.

Let me know how it goes,
Dave Wragg


diff -uar linux-2.4.2/arch/i386/kernel/mtrr.c linux-2.4.2.cyrix/arch/i386/kernel/mtrr.c
--- linux-2.4.2/arch/i386/kernel/mtrr.c	Thu Feb 22 15:24:53 2001
+++ linux-2.4.2.cyrix/arch/i386/kernel/mtrr.c	Wed Mar 14 22:28:02 2001
@@ -538,7 +538,7 @@
      * Note: shift==0xf means 4G, this is unsupported.
      */
     if (shift)
-      *size = (reg < 7 ? 0x1UL : 0x40UL) << shift;
+      *size = (reg < 7 ? 0x1UL : 0x40UL) << (shift - 1);
     else
       *size = 0;
 

  reply	other threads:[~2001-03-14 22:58 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-03-13 19:20 another Cyrix/mtrr problem? Bob_Tracy
2001-03-14  0:20 ` davej
2001-03-14  2:48   ` Bob_Tracy
2001-03-14 22:57     ` David Wragg [this message]
2001-03-15 13:34       ` Bob_Tracy
2001-03-16  7:15       ` Joerg Diederich

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