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Date: Sun, 6 Jun 2004 02:17:58 -0700
From: David Schultz <das@FreeBSD.ORG>
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Subject: Re: cvs commit: src/sys/amd64/amd64 fpu.c
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On Sun, Jun 06, 2004, David Schultz wrote:
> das         2004-06-06 09:16:02 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/amd64/amd64      fpu.c 
>   Log:
>   Back out revision 1.150, since dwmalone reports that it causes a panic
>   upon startup on his machine.

It would be great if someone could pick this up and devise the
appropriate fix.  I want to see this bug fixed, but I don't have the
hardware to do amd64 kernel hacking.  I'm happy to help anyone who is
interested.

So far I have one report that the patch I just backed out seems to
work, and another that it panics on startup, so this seems to point to
a CPU-specific problem.  ldmxcsr is supposed to fail if an attempt is
made to set unsupported bits in the CSR, but at the same time, the
defaults in the AMD64 architecture manual ought to work!  If this is
indeed the problem, there is a simple way to work around it.