From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763649AbYAYIBb (ORCPT ); Fri, 25 Jan 2008 03:01:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763011AbYAYHtj (ORCPT ); Fri, 25 Jan 2008 02:49:39 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:2083 "EHLO spitz.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1762162AbYAYHti (ORCPT ); Fri, 25 Jan 2008 02:49:38 -0500 Date: Fri, 25 Jan 2008 07:49:10 +0000 From: Pavel Machek To: "H. Peter Anvin" Cc: "Rafael J. Wysocki" , Jeremy Fitzhardinge , Ian Campbell , Ingo Molnar , Mika =?iso-8859-1?Q?Penttil=E4?= , 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. Message-ID: <20080125074910.GD4134@ucw.cz> References: <1201167544.30671.64.camel@cthulhu.hellion.org.uk> <47990BDC.4070008@zytor.com> <479912B0.2080506@goop.org> <479913BA.8000506@zytor.com> <47991809.9060903@goop.org> <47991A6C.8060007@zytor.com> <479921F5.9020902@goop.org> <4799247C.6090008@zytor.com> <20080125002054.GA2059@elf.ucw.cz> <47992D0E.2070700@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47992D0E.2070700@zytor.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2008-01-24 16:27:58, H. Peter Anvin wrote: > Pavel Machek wrote: > >>> > >>I just looked at the ACPI suspend code, and it looks > >>like it hacks its own identity map at runtime. Pavel, > >>am I reading that code right? > > > >Yes, I think so, I believe we do it on both 32 and 64 > >bit now. > > > > So the background to this... we need an identity map to > trampoline at early boot, obviously, but we'd like it to > not stick around more than necessary. We have > zap_low_mappings() now but it's not really sufficient. > > Secondary SMP processors need these mappings during > trampolining -- presumably including CPU hotplug -- and > I'm suspecting it might simply make sense to use a > separate set of page tables (with both the identity and > the kernel map) for trampolining and just keep them > around. That way they would be usable for ACPI as well. That would enable some cleanups, yes. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html