From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758646AbYAXWoi (ORCPT ); Thu, 24 Jan 2008 17:44:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753520AbYAXWob (ORCPT ); Thu, 24 Jan 2008 17:44:31 -0500 Received: from terminus.zytor.com ([198.137.202.10]:33979 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751710AbYAXWoa (ORCPT ); Thu, 24 Jan 2008 17:44:30 -0500 Message-ID: <479913BA.8000506@zytor.com> Date: Thu, 24 Jan 2008 14:39:54 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Ian Campbell , Ingo Molnar , =?UTF-8?B?TWlrYSBQZW50dGlsw6Q=?= , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "Eric W. Biederman" Subject: Re: [PATCH] x86: Construct 32 bit boot time page tables in native format. References: <1200758937-22386-2-git-send-email-ijc@hellion.org.uk> <47939363.8040603@kolumbus.fi> <1200950633.15491.21.camel@cthulhu.hellion.org.uk> <479510CE.7010706@zytor.com> <1200951996.15491.28.camel@cthulhu.hellion.org.uk> <479551FD.5040801@zytor.com> <1201023401.5643.52.camel@localhost.localdomain> <479634A9.1090908@zytor.com> <1201031325.15491.66.camel@cthulhu.hellion.org.uk> <47964B7B.9000905@zytor.com> <20080122203611.GA12892@elte.hu> <1201121530.30671.15.camel@cthulhu.hellion.org.uk> <4797E487.8010108@goop.org> <1201167544.30671.64.camel@cthulhu.hellion.org.uk> <47990BDC.4070008@zytor.com> <479912B0.2080506@goop.org> In-Reply-To: <479912B0.2080506@goop.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > H. Peter Anvin wrote: >> In other words, reusing the early page tables isn't all that >> straightforward. It may easily be that it's better to build a new set >> of page tables from scratch, however, it would *still* be beneficial >> to have the early page tables be in the same format as the later one, >> since it lets us use the fixmap area, and therefore >> {bt,early}_ioremap() much sooner. > > Yes, and it simplifies Xen as it always starts guest domains in the > appropriate pagetable mode and doesn't let the guest change it on the > fly. If early_ioremap depends on non-PAE early pagetables in an > otherwise PAE kernel, we'd need to go to some effort to make sure all > the early_ioremap stuff is skipped (which would be possible but > unpleasant for domU, but very bad in dom0). > Yeah, and it's ugly for the kernel proper, so that bit is a no-brainer. It's just a matter of hammering out the details. It doesn't sound from the above that you have any opinion either way about reusing the initial page tables or creating a new set, as long as they're in the same format. -hpa