From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753069AbbCUBJD (ORCPT ); Fri, 20 Mar 2015 21:09:03 -0400 Received: from mail-lb0-f175.google.com ([209.85.217.175]:35917 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752712AbbCUBJB (ORCPT ); Fri, 20 Mar 2015 21:09:01 -0400 MIME-Version: 1.0 In-Reply-To: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> From: Andy Lutomirski Date: Fri, 20 Mar 2015 18:08:39 -0700 Message-ID: Subject: Re: [PATCH v1 00/47] mtrr/x86/drivers: bury MTRR To: "Luis R. Rodriguez" Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Juergen Gross , Jan Beulich , Borislav Petkov , Suresh Siddha , venkatesh.pallipadi@intel.com, Dave Airlie , "linux-kernel@vger.kernel.org" , Linux Fbdev development list , X86 ML , "xen-devel@lists.xenproject.org" , "Luis R. Rodriguez" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 20, 2015 at 4:17 PM, Luis R. Rodriguez wrote: > From: "Luis R. Rodriguez" > > When a system has PAT support enabled you don't need to be > using MTRRs. Andy had added arch_phys_wc_add() long ago to > help with this but not all drivers were converted over. We > have to take care to only convert drivers where we know that > the proper ioremap_wc() API has been used. Doing this requires > a bit of work on verifying the driver split out the ioremap'd > areas -- and if not doing that ourselves. Verifying a driver > uses the same areas can be hard but with a bit of love Coccinelle > can help with that. > > We're motivated to change drivers for a few reasons: > > 1) Take advantage of PAT when available > > 2) Help with the goal of eventually using _PAGE_CACHE_UC over > _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (de33c442e) Nice! --Andy From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Lutomirski Date: Sat, 21 Mar 2015 01:08:39 +0000 Subject: Re: [PATCH v1 00/47] mtrr/x86/drivers: bury MTRR Message-Id: List-Id: References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> In-Reply-To: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Luis R. Rodriguez" Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Juergen Gross , Jan Beulich , Borislav Petkov , Suresh Siddha , venkatesh.pallipadi@intel.com, Dave Airlie , "linux-kernel@vger.kernel.org" , Linux Fbdev development list , X86 ML , "xen-devel@lists.xenproject.org" , "Luis R. Rodriguez" On Fri, Mar 20, 2015 at 4:17 PM, Luis R. Rodriguez wrote: > From: "Luis R. Rodriguez" > > When a system has PAT support enabled you don't need to be > using MTRRs. Andy had added arch_phys_wc_add() long ago to > help with this but not all drivers were converted over. We > have to take care to only convert drivers where we know that > the proper ioremap_wc() API has been used. Doing this requires > a bit of work on verifying the driver split out the ioremap'd > areas -- and if not doing that ourselves. Verifying a driver > uses the same areas can be hard but with a bit of love Coccinelle > can help with that. > > We're motivated to change drivers for a few reasons: > > 1) Take advantage of PAT when available > > 2) Help with the goal of eventually using _PAGE_CACHE_UC over > _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (de33c442e) Nice! --Andy