From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [GIT PULL] iommu: Kill off pgsize_bitmap field from struct iommu_ops Date: Thu, 2 Apr 2015 09:58:23 +0100 Message-ID: <20150402085821.GA18320@arm.com> References: <20150327171946.GL1562@arm.com> <1427894051.22236.6.camel@infradead.org> <20150401133908.GI1552@arm.com> <1427896377.22236.8.camel@infradead.org> <20150401140512.GJ1552@arm.com> <1427898490.22236.10.camel@infradead.org> <20150401143904.GL1552@arm.com> <1427899570.22236.14.camel@infradead.org> <20150401163618.GN1552@arm.com> <20150401212854.GK4441@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150401212854.GK4441-zLv9SwRftAIdnm+yROfE0A@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: "joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org" 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" , David Woodhouse , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: iommu@lists.linux-foundation.org On Wed, Apr 01, 2015 at 10:28:54PM +0100, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org wrote: > On Wed, Apr 01, 2015 at 05:36:18PM +0100, Will Deacon wrote: > > The issue (speaking in terms of the ARM SMMU, since that's what I'm familiar > > with) is that we don't know the page sizes until we've chosen our > > translation regime. > > Can't you hard-code one regime in the driver and just don't use the > others? Or might a SMMU only support a subset of the possible regimes? Indeed, we can end up with systems that only support a subset of the regimes. Different workloads may also benefit from different regimes due to better TLB utilisation, but there's not currently a way to bias the page table allocator away from the CPU page size. Will