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Date: Fri, 23 Oct 2009 08:10:47 +0900
From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Eric Anholt <eric@anholt.net>,
       Thomas Schlichter <thomas.schlichter@web.de>,
       Ingo Molnar <mingo@elte.hu>, Jan Beulich <JBeulich@novell.com>,
       Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
       Robert Hancock <hancockrwd@gmail.com>,
       Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
       "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
       Tejun Heo <tj@kernel.org>, "x86@kernel.org" <x86@kernel.org>,
       Yinghai Lu <yinghai@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
       Arjan van de Ven <arjan@linux.intel.com>,
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       Ingo Molnar <mingo@redhat.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Thomas Hellstrom <thellstrom@vmware.com>,
       "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [RFC Patch] use MTRR for write combining if PAT is not
 available
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On Thu, 22 Oct 2009 14:47:30 -0700
Suresh Siddha <suresh.b.siddha@intel.com> wrote:

> On Thu, 2009-10-22 at 08:34 -0700, Eric Anholt wrote:
> > Can we just not create the _wc sysfs entry if we don't have PAT?  I
> > don't think there's userland relying on its presence as opposed to
> > the non-_wc entry.
> 
> Yes indeed. Jesse do you see an issue with this? This is simple and
> clean. Thanks Eric.

Yeah, I think that will be fine.  In fact, older versions of
libpciaccess will behave better if we do it that way (iirc it only
allocates an MTRR if the resource_wc file doesn't exist or fails to get
mapped).

Jesse
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