From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v2] Intel IOMMU patch to reprocess RMRR info Date: Fri, 28 Sep 2012 11:43:01 +0200 Message-ID: <20120928094301.GH10549@amd.com> References: <20120918164955.12296.28799.sendpatchset@tmingo.houston.hp.com> <1348778200.2320.241.camel@ul30vt.home> <9774516974AF5F4C8A2C3C69CD3412332338F452@G1W3651.americas.hpqcorp.net> <1348781647.2320.264.camel@ul30vt.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1348781647.2320.264.camel-85EaTFmN5p//9pzu0YdTqQ@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: Alex Williamson Cc: "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "Khan, Shuah" , David Woodhouse , "Mingarelli, Thomas" List-Id: iommu@lists.linux-foundation.org On Thu, Sep 27, 2012 at 03:34:07PM -0600, Alex Williamson wrote: > It really seems like RMRRs are incompatible with IOMMU API use > though. I don't think so. The concept of RMRR is just not defined well enough (like the concept of unity mappings on the AMD side which is similar to RMRR). The definition says, that any memory region must be mapped at any time for the device. But that is not true (at least I have no counter-example yet). The right definition would be, that the RMRR regions are only necessary as long as the operating system does not control the particular device. And assigning a device to a guest also counts a 'taking control over the device'. Joerg