From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Lutomirski Subject: Re: [PATCH v1 00/47] mtrr/x86/drivers: bury MTRR Date: Fri, 20 Mar 2015 18:08:39 -0700 Message-ID: References: <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 Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YZ7uP-0003Qn-OZ for xen-devel@lists.xenproject.org; Sat, 21 Mar 2015 01:09:02 +0000 Received: by lbbrr9 with SMTP id rr9so22078414lbb.0 for ; Fri, 20 Mar 2015 18:08:59 -0700 (PDT) In-Reply-To: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Luis R. Rodriguez" Cc: Juergen Gross , Linux Fbdev development list , X86 ML , Suresh Siddha , "Luis R. Rodriguez" , venkatesh.pallipadi@intel.com, "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , Ingo Molnar , Jan Beulich , "H. Peter Anvin" , Dave Airlie , Thomas Gleixner , Borislav Petkov List-Id: xen-devel@lists.xenproject.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