From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754967AbYAORdT (ORCPT ); Tue, 15 Jan 2008 12:33:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751229AbYAORdM (ORCPT ); Tue, 15 Jan 2008 12:33:12 -0500 Received: from gw.goop.org ([64.81.55.164]:43506 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750791AbYAORdL (ORCPT ); Tue, 15 Jan 2008 12:33:11 -0500 Message-ID: <478CEE45.1040006@goop.org> Date: Tue, 15 Jan 2008 09:32:53 -0800 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Andi Kleen CC: Ingo Molnar , tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: Folding _PAGE_PWT into _PAGE_PCD (was Re: unify pagetable accessors patch causes double fault II) References: <20080114094814.GA28300@basil.nowhere.org> <20080114125638.GA9510@basil.nowhere.org> <20080114130620.GA14057@elte.hu> <20080114135811.GA16190@one.firstfloor.org> <478BDC43.6050105@goop.org> <20080114222349.GA23409@one.firstfloor.org> <478BE628.7090008@goop.org> <20080115135317.GA13493@elte.hu> <478CEA82.9010606@goop.org> <20080115172346.GB2377@one.firstfloor.org> In-Reply-To: <20080115172346.GB2377@one.firstfloor.org> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: >> BTW, I just noticed that _PAGE_PWT has been folded into _PAGE_PCD. This >> seems like a really bad idea to me, since it breaks the rule that >> _PAGE_X == 1 << _PAGE_BIT_X. I can't think of a specific place where >> this would cause problems, but this kind of non-uniformity always ends >> up biting someone in the arse. >> > > Agreed that it's a bad idea. > > >> I think having a specific _PAGE_NOCACHE which combines these bits is a >> better approach. >> > > CPA series adds that already > > +/* Needs special handling for large pages */ > +#define _PAGE_CACHE (_PAGE_PCD|_PAGE_PWT|_PAGE_PAT) > Good, but isn't the name _PAGE_CACHE misleading? Or does it mean something else in the context of PAT? J