Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753753Ab3GIXyv (ORCPT ); Tue, 9 Jul 2013 19:54:51 -0400 Received: from sous-sol.org ([216.99.217.87]:47497 "EHLO sequoia2.sous-sol.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752792Ab3GIXyt (ORCPT ); Tue, 9 Jul 2013 19:54:49 -0400 X-Greylist: delayed 1826 seconds by postgrey-1.27 at vger.kernel.org; Tue, 09 Jul 2013 19:54:42 EDT Date: Tue, 9 Jul 2013 16:22:52 -0700 From: Chris Wright To: Guenter Roeck Cc: Bjorn Helgaas , David Woodhouse , "linux-kernel@vger.kernel.org" , "open list:INTEL IOMMU (VT-d)" Subject: Re: WARNING: at drivers/iommu/dmar.c:484 warn_invalid_dmar with Intel Motherboard Message-ID: <20130709232252.GB2676@sequoia2.sous-sol.org> References: <20130709202406.GA11867@roeck-us.net> <20130709223106.GA16429@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130709223106.GA16429@roeck-us.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1237 Lines: 30 * Guenter Roeck (linux@roeck-us.net) wrote: > On Tue, Jul 09, 2013 at 03:05:39PM -0600, Bjorn Helgaas wrote: > > [+cc Joerg, David, iommu list] > > > > On Tue, Jul 9, 2013 at 2:24 PM, Guenter Roeck wrote: > > > I started seeing this problem after updating the BIOS trying fix another issue, > > > though I may have missed it earlier. > > > > > > I understand this is a BIOS bug. Would be great if someone can pass this on > > > to Intel BIOS engineers. > > > > Maybe. It'd be nice if Linux handled it better, though. > > > If anyone has an idea how to do that, I'll be happy to write a patch. I'm not sure there's much you can do. The BIOS is saying there's a DMAR unit, and then saying the registers are at addr 0x0. The kernel is simply warning you about the invalid DMAR table entry. One thing I've seen is the BIOS zeroing the base register address when VT-d is disabled in BIOS. So, Guenter, a "fix" may be simply enabling VT-d in the BIOS. thanks, -chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/