From: Thomas Schlichter <thomas.schlichter@web.de>
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC Patch] use MTRR for write combining if PAT is not available
Date: Tue, 20 Oct 2009 22:35:12 +0200
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Cc: Jan Beulich <JBeulich@novell.com>,
       Suresh Siddha <suresh.b.siddha@intel.com>, arjan@linux.intel.com,
       dri-devel@lists.sourceforge.net, hancockrwd@gmail.com, hmh@hmh.eng.br,
       hpa@zytor.com, jbarnes@virtuousgeek.org, jeremy.fitzhardinge@citrix.com,
       linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de,
       thellstrom@vmware.com, tj@kernel.org, venkatesh.pallipadi@intel.com,
       x86@kernel.org, yinghai@kernel.org
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Ingo Molnar wrote:
> * Thomas Schlichter <thomas.schlichter@web.de> wrote:
> > > or Perhaps just try to add mtrr only for the pci mmap case like the
> > > 4th patch in this series..
> >
> > I'd prefer this! ;-)
> 
> Hm, we could perhaps do that - but i think we should only do that on
> systems that have PAT disabled.

The patch I sent should do exactly that.

> Which brings up the question of how to properly QA such a narrow segment
> of the market. Maybe disabling CONFIG_X86_PAT should enable that logic
> too.

When CONFIG_X86_PAT is disabled, pat_enabled is 0, and thus my new code should 
be active. Or do I miss something?

What do you think about the latest version of my patch series I just sent?

Kind regards,
  Thomas
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