From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756666AbYAORUu (ORCPT ); Tue, 15 Jan 2008 12:20:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752541AbYAORUn (ORCPT ); Tue, 15 Jan 2008 12:20:43 -0500 Received: from one.firstfloor.org ([213.235.205.2]:55978 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077AbYAORUm (ORCPT ); Tue, 15 Jan 2008 12:20:42 -0500 Date: Tue, 15 Jan 2008 18:23:46 +0100 From: Andi Kleen To: Jeremy Fitzhardinge Cc: Ingo Molnar , Andi Kleen , 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) Message-ID: <20080115172346.GB2377@one.firstfloor.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <478CEA82.9010606@goop.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 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) + -Andi