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Date: Thu, 29 Nov 2007 09:49:53 +0100
From: Kris Kennaway <kris@FreeBSD.org>
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To: Joseph Koshy <jkoshy@FreeBSD.org>
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Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/dev/hwpmc hwpmc_x86.c
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Joseph Koshy wrote:
> jkoshy      2007-11-29 06:43:59 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/dev/hwpmc        hwpmc_x86.c 
>   Log:
>   Revert revision 1.4.
>   
>   Intel CPUs with family 0x6, model 0xE and later (i.e., Intel Core(TM))
>   have a PMC architecture that differs somewhat from previous CPUs in
>   family 0x6.  Even though the basic programming model is similar, the
>   documented set of legal values that may be loaded into their PMC MSRs
>   differs from that of the previous PMCs in family 0x6 and reusing bit
>   values valid for the older PMCs could result in undefined behaviour in
>   the general case.
>   
>   Revision  Changes    Path
>   1.6       +1 -1      src/sys/dev/hwpmc/hwpmc_x86.c

What is your expected timeline for fixing this and the other missing CPU 
family support (Intel Woodcrest, etc)?  It's a serious limitation to not 
be able to run hwpmc on modern CPUs, and I argue that a partial 
implementation is much better than no implementation.

Kris