From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030446Ab2COOyO (ORCPT ); Thu, 15 Mar 2012 10:54:14 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:43951 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964859Ab2COOyI (ORCPT ); Thu, 15 Mar 2012 10:54:08 -0400 Date: Thu, 15 Mar 2012 14:54:03 +0000 From: Matthew Garrett To: "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, x86@kernel.org, matt.fleming@intel.com Subject: Re: [PATCH] EFI: Only set regions uncacheable if they support it Message-ID: <20120315145403.GA5321@srcf.ucam.org> References: <1331819798-1955-1-git-send-email-mjg@redhat.com> <4F61F5E6.8060509@zytor.com> <20120315140708.GA3395@srcf.ucam.org> <4F61FA14.6020203@zytor.com> <20120315142445.GA4357@srcf.ucam.org> <4F61FC8E.8070109@zytor.com> <20120315143308.GA4382@srcf.ucam.org> <4F61FE7E.9060600@zytor.com> <20120315144236.GB4650@srcf.ucam.org> <4F62011D.4000708@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F62011D.4000708@zytor.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 15, 2012 at 07:47:57AM -0700, H. Peter Anvin wrote: > WTF?! That should be UC at all times... it isn't even WC-capable. > Furthermore, we may need this region (assuming there is actually a video > card there.) I don't think we'll ever use this region on UEFI. What I have from Intel is: "It looks like this is happening when the kernel iterates over the various regions in the EFI memory map. It hits a region starting at 0xA0000 and attempts to do a CLFLUSH instruction on that address. This is explicitly forbidden by the SAD in (codename), thus the Machine Check." > What do the fixed MTRRs look like? Unsure. I'll try to find out. -- Matthew Garrett | mjg59@srcf.ucam.org