Re: [RFC Patch] use MTRR for write combining if PAT is notavailable

From: Jesse Barnes
Date: Thu Oct 22 2009 - 19:11:04 EST


On Thu, 22 Oct 2009 14:47:30 -0700
Suresh Siddha <suresh.b.siddha@xxxxxxxxx> 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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