From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760303AbZEMOjm (ORCPT ); Wed, 13 May 2009 10:39:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758744AbZEMOjb (ORCPT ); Wed, 13 May 2009 10:39:31 -0400 Received: from gw.goop.org ([64.81.55.164]:45537 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757959AbZEMOja (ORCPT ); Wed, 13 May 2009 10:39:30 -0400 Message-ID: <4A0ADBA2.2020300@goop.org> Date: Wed, 13 May 2009 07:39:30 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Ingo Molnar CC: the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel Subject: Re: [GIT PULL] xen /proc/mtrr implementation References: <1242170864-13560-1-git-send-email-jeremy@goop.org> <20090513133021.GA7277@elte.hu> In-Reply-To: <20090513133021.GA7277@elte.hu> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > i never got a reply to my question for your previous submission: > > http://lkml.indiana.edu/hypermail/linux/kernel/0905.1/00152.html > That was in response to the mtrr patch in the dom0/core series. > Please dont post patches with ugly TODO items in them. I removed them in the repost. > Also, a more general objection is that /proc/mtrr is a legacy > interface, we dont really want to extend its use. It's not an extended use; its just making the existing interface work under Xen (ie, not breaking the userspace ABI). The only other alternatives would be to 1) use Kconfig to prevent MTRR and Xen from being set at the same time, or 2) put a runtime hack in to disable MTRR when running under Xen. Neither seems like a good idea when we can just keep the interface working. > The Xen hypervisor > should get proper PAT support instead ... Well, it has PAT support, but there's an issue that the Xen PAT setup isn't quite the same as Linux's (but I thought you were cc:d on the discussion about that). We need to sort out some details about the precise mechanism, but it looks like we'll be able to support PAT in Linux guests relatively easily (but not immediately). J