From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933406AbXLNA27 (ORCPT ); Thu, 13 Dec 2007 19:28:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933223AbXLNA2a (ORCPT ); Thu, 13 Dec 2007 19:28:30 -0500 Received: from gir.skynet.ie ([193.1.99.77]:36184 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932154AbXLNA22 (ORCPT ); Thu, 13 Dec 2007 19:28:28 -0500 Date: Fri, 14 Dec 2007 00:28:25 +0000 (GMT) From: Dave Airlie To: venkatesh.pallipadi@intel.com cc: ak@muc.de, ebiederm@xmission.com, rdreier@cisco.com, torvalds@linux-foundation.org, gregkh@suse.de, davej@redhat.com, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, akpm@linux-foundation.org, arjan@infradead.org, jesse.barnes@intel.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 00/12] PAT 64b: PAT support for X86_64 In-Reply-To: <20071213235543.568682000@intel.com> Message-ID: References: <20071213235543.568682000@intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Yes. It is that wonderful time of the year again. > No, no. We are not talking about holiday season or new year here. > > We are talking about one another rehash of "why we do not support PAT in x86" > question and series of patches that implement some PAT support before going > into hibernation again. Only difference is that we hope to take this little > further this time and may be really get this support into > upstream kernel soon. Woot, PAT support: this time we mean it!! I'll just give one comment after a reading your todo.. > * Do we need to allow RAM pages to be mapped as WC? If not, then > we don't need to follow the TLB flush mechanism (make pte not present, > flush, and set pte with new mapping) mentioned in section 10.12.4 of SDM > Vol3a. Yes, the main use for GPUs is to have RAM pages mapped WC, and placed into a GART on the GPU side, currently for Intel IGD we are okay as the CPU can access the GPU GART aperture, but other chips exist where this isn't possible, I think poulsbo and possible some of the AMD IGPs.. Dave.