Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752745AbYJDGKd (ORCPT ); Sat, 4 Oct 2008 02:10:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751238AbYJDGKY (ORCPT ); Sat, 4 Oct 2008 02:10:24 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:41632 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751203AbYJDGKX (ORCPT ); Sat, 4 Oct 2008 02:10:23 -0400 Subject: RE: [PATCH 2/2]Add Variable Page Size and IA64 Support in Intel IOMMU: IA64 Specific Part From: David Woodhouse To: "Yu, Fenghua" Cc: Bjorn Helgaas , "Luck, Tony" , Jesse Barnes , Ingo Molnar , Avi Kivity , Stephen Rothwell , Andrew Morton , LKML , "linux-ia64@vger.kernel.org" In-Reply-To: References: <20081001165750.GA21272@linux-os.sc.intel.com> <200810020951.08408.bjorn.helgaas@hp.com> <200810030941.42800.bjorn.helgaas@hp.com> Content-Type: text/plain Date: Sat, 04 Oct 2008 07:09:57 +0100 Message-Id: <1223100597.30832.37.camel@macbook.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 (2.22.3.1-1.fc9) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1089 Lines: 26 On Fri, 2008-10-03 at 17:53 -0700, Yu, Fenghua wrote: > >Architecturally, I'm surprised that ia64 would need to actually do a > >cache flush. I would think the VT-d hardware would do coherent > accesses which would make the cache flush unnecessary. > > VT-d hardware supports both non cache coherency and cache coherency by > bit Coherency in Extended Capabilities Register. But is the version without the cache coherency actually going to be _seen_ on IA64? > Could you please point me to the doc that explicitly says that > architecturally ia64 doesn't need cache flush? For safety, we can always make the driver just refuse to initialise on IA64 if the cache coherency bit isn't set. -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/