From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758237AbZAOI60 (ORCPT ); Thu, 15 Jan 2009 03:58:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760223AbZAOI5m (ORCPT ); Thu, 15 Jan 2009 03:57:42 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:36643 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759530AbZAOI5l (ORCPT ); Thu, 15 Jan 2009 03:57:41 -0500 Date: Thu, 15 Jan 2009 09:57:28 +0100 From: Ingo Molnar To: Jan Beulich Cc: "H. Peter Anvin" , tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: simplify HIGHMEM-related Kconfig entries Message-ID: <20090115085728.GA28607@elte.hu> References: <496DE927.76E4.0078.0@novell.com> <496E3F7D.2060908@zytor.com> <496F0796.76E4.0078.0@novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <496F0796.76E4.0078.0@novell.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jan Beulich wrote: > >>> "H. Peter Anvin" 14.01.09 20:39 >>> > >Jan Beulich wrote: > >> Additionally remove the dependency of X86_PAE on !HIGHMEM4G - at least > >> I can't understand why that dependency existed. > > > >At least originally, the meaning of the x86 highmem entries were: > > > > No highmem - No highmem, no PAE > > HIGHMEM4G - Highmem, no PAE > > HIGHMEM64G - Highmem, PAE > > > >So X86_PAE and HIGHMEM4G is a bit of a contradiction. I haven't looked > >at the logic in detail, or remember offhand if there have been any > >weakening of the definitions above; e.g. someone could have implemented > >a way to do PAE without highmem, to get access to the NX bits. > > Exactly - .23 made PAE an independently selectable option (in > particular, the no-highmem+PAE combination is now valid), but I can't > see why it added the !HIGHMEM4G dependency. There's no deep reason, it just has never really been tested that way. I think we should try it. Ingo