From owner-freebsd-current  Thu Jan 31  7:50:46 2002
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From: "Cameron, Frank" <Cameron@ctc.com>
To: "'Kenneth Culver'" <culverk@yumyumyum.org>,
	Terry Lambert <tlambert2@mindspring.com>
Cc: David Malone <dwmalone@maths.tcd.ie>,
	"'freebsd-bugs@freebsd.org'" <freebsd-bugs@FreeBSD.ORG>,
	"'freebsd-current@freebsd.org'" <freebsd-current@FreeBSD.ORG>
Subject: RE: AMD AGP Bug
Date: Thu, 31 Jan 2002 10:50:45 -0500
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From what was posted on the linux-kernel list the problem is the OS
doing the wrong thing not the hardware.  I originally asked the
question (albeit not worded as clearly as I should have) because if
Microsoft and Linux programmers made the same mistake, might
FreeBSD have also.

> -----Original Message-----
> From: Kenneth Culver [mailto:culverk@yumyumyum.org]
> Sent: Thursday, January 31, 2002 10:42 AM
> To: Terry Lambert
> Cc: David Malone; Cameron, Frank; 'freebsd-bugs@freebsd.org';
> 'freebsd-current@freebsd.org'
> Subject: Re: AMD AGP Bug
> 
> 
> > There's actually a seperate TLB bug, but FreeBSD doesn't
> > trigger that one, either (Linux can tickle it, when there
> > are certain specific circumstances met).
> >
> Well, I think I know what you're talking about, linux 
> allocates agpgart
> memory without setting a "non-cacheable" bit, and then the 
> agp card writes
> to that memory, but the cpu cached it already, which makes 
> the cache wrong
> or something like that, and causes the crashes/hangs. I know this is a
> greatly simplified version of the real problem, but I think this is a
> linux bug not necesarily an amd bug.
> 
> Ken
> 

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