From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [GIT PULL] iommu: Kill off pgsize_bitmap field from struct iommu_ops Date: Tue, 31 Mar 2015 16:24:40 +0200 Message-ID: <20150331142440.GD22683@8bytes.org> References: <20150327171946.GL1562@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150327171946.GL1562-5wv7dgnIgG8@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: Will Deacon Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org, Varun.Sethi-KZfg59tc24xl57MIdRCFDg@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hi Will, On Fri, Mar 27, 2015 at 05:19:46PM +0000, Will Deacon wrote: > Please can you pull the following IOMMU changes for 4.1? They move the > per-iommu_ops pgsize_bitmap field into the iommu_domain, which allows > IOMMUs such as the ARM SMMU to support different page sizes within a > given SoC. I have some concerns about the direction taken with this patch-set. The goal for the IOMMU-API is still to have domains that can be attached to arbitrary devices (even when mappings already exist). But with this patch-set we move into a direction where a domain can only be used on IOMMUs that support the page-sizes required by the domain. In the end this would be visible to the user of the IOMMU-API, which is not what we want. I can understand the motivation behind these patches, but we need to think about how this could work with the desired semantics of the IOMMU-API. Joerg