From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: WARNING: at drivers/iommu/dmar.c:484 warn_invalid_dmar with Intel Motherboard Date: Wed, 14 Aug 2013 11:36:12 +0200 Message-ID: <20130814093607.GB4491@8bytes.org> References: <20130709202406.GA11867@roeck-us.net> <20130709223106.GA16429@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20130709223106.GA16429-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Guenter Roeck Cc: Bjorn Helgaas , "open list:INTEL IOMMU (VT-d)" , David Woodhouse , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: iommu@lists.linux-foundation.org On Tue, Jul 09, 2013 at 03:31:06PM -0700, Guenter Roeck 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 doubt that we can do anything meaningful here. The BIOS is broken in a way so that we can't use the IOMMU in Linux. We can patch away the WARN_ON and make it a sumple FW_BUG message, but the noise a WARN_ON makes maybe help getting this issue fixed. But I may be convinced otherwise, if people think this WARN_ON is not worth it. Joerg