From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754113AbYEJGTn (ORCPT ); Sat, 10 May 2008 02:19:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751919AbYEJGTd (ORCPT ); Sat, 10 May 2008 02:19:33 -0400 Received: from fg-out-1718.google.com ([72.14.220.152]:9192 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751540AbYEJGTb (ORCPT ); Sat, 10 May 2008 02:19:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=PkrujFt3IyDUQnH3Xupmvxv/BegyKsvN7YeyLPm7DnrVLVNQ0XLZ025X/d0UqY3kzNS56deanrXD7p5TddttkmhxJ01x09Ho6hbMApC/MEgRbVuY/s6kXjg0YaqwbYPfpQgpHqlS8ejuAw0SDy/ayTwnau7uqS5WUz61MNUoO00= Message-ID: <21d7e9970805092319n1d31be36h2f2c7d46622f46c8@mail.gmail.com> Date: Sat, 10 May 2008 16:19:27 +1000 From: "Dave Airlie" To: "Pallipadi, Venkatesh" Subject: Re: [git head] X86_PAT & mprotect Cc: "Ingo Molnar" , "Hugh Dickins" , "Frans Pop" , "Barnes, Jesse" , linux-kernel@vger.kernel.org, "Packard, Keith" , "Yinghai Lu" , "Andrew Morton" , "Linus Torvalds" , "H. Peter Anvin" , "Thomas Gleixner" , "Nick Piggin" , "Jesse Barnes" In-Reply-To: <924EFEDD5F540B4284297C4DC59F3DEE010471B6@orsmsx423.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200805022122.03576.elendil@planet.nl> <200805051932.41827.elendil@planet.nl> <20080506224240.GA18706@linux-os.sc.intel.com> <20080507070217.GD32195@elte.hu> <20080507232326.GB10757@linux-os.sc.intel.com> <20080509100818.GD19617@elte.hu> <20080509200519.GA10897@linux-os.sc.intel.com> <21d7e9970805091511n2c6b6cfeu433b184d3031196d@mail.gmail.com> <924EFEDD5F540B4284297C4DC59F3DEE010471B6@orsmsx423.amr.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 10, 2008 at 8:20 AM, Pallipadi, Venkatesh wrote: > > > > >-----Original Message----- > >From: Dave Airlie [mailto:airlied@gmail.com] > >Sent: Friday, May 09, 2008 3:11 PM > >To: Pallipadi, Venkatesh > >Cc: Ingo Molnar; Hugh Dickins; Frans Pop; Barnes, Jesse; > >linux-kernel@vger.kernel.org; Packard, Keith; Yinghai Lu; > >Andrew Morton; Linus Torvalds; H. Peter Anvin; Thomas > >Gleixner; Nick Piggin; Jesse Barnes > >Subject: Re: [git head] X86_PAT & mprotect > > > >On Sat, May 10, 2008 at 6:05 AM, Venki Pallipadi > > wrote: > >> On Fri, May 09, 2008 at 12:08:18PM +0200, Ingo Molnar wrote: > >> > > >> > * Venki Pallipadi wrote: > >> > > >> > > > I've tried doing it slightly differently below, don't > >know whether > >> > > > you'll consider it an improvement or not. > >> > > > >> > > Hugh: Thanks for looking into this. Yes. I like your > >modified patch. > >> > > Simpler and smaller. > >> > > >> > i have stuck your original patch into testing and nothing > >blew up so > >> > far. Due to the mm/ bits this is not for the scope of x86.git, but > >> > obviously it all looks good and is .26-worthy to me: > >> > > >> > Acked-by: Ingo Molnar > >> > Tested-by: Ingo Molnar > >> > > >> > Venki, could you please send a full patch against -git that has > >> > everything from Hugh included, with an updated changelog, for > >> > Linus/Andrew to ack/apply? > >> > > >> > >> Ingo, > >> > >> Split up the patch into two parts as the pci part was > >unrelated to mprotect > >> problem in a sense. > >> > >> Here is the first patch. > >> > >> Thanks, > >> Venki > >> > >> > >> Some versions of X used the mprotect workaround to change > >caching type from > >> > >> UC to WB, so that it can then use mtrr to program WC for > >that region [1]. > >> Change the mmap of pci space through /sys or /proc > >interfaces from UC to > >> UC_MINUS. With this change, X will not need to use mprotect > >> workaround to get WC type. > >> Also the bug with mprotect which lets caller to change PAT > >bits is fixed in > >> the follow on patch. So, this X workaround will stop > >working as well. > >> > > > >Wow this kinda puts X in a nasty position, we have 2.6.25 and > >previous kernels > >where we use the original /sys interfaces and nasty hack to > >workaround, but on 2.6.26 we magically need to > >switch to the /sys _uc interfaces or the users X will slow down. > > > > No. With 2.6.26 you can still use same /sys resource file, without > the mprotect workaround and set the MTRR as before. > > The change from UC to UC_MINUS in this patch ensures that the > X drivers MTRR will take precedence and X does not need any mprotect > hacks. > Cool just making sure. Keithp, I hope we didn't error check the mremap return values :) Dave.