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[142.134.23.187]) by smtp.gmail.com with ESMTPSA id h7-20020a4abb87000000b0057e7c1118b9sm238914oop.31.2023.11.23.08.59.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Nov 2023 08:59:23 -0800 (PST) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1r6D2w-001rih-KY; Thu, 23 Nov 2023 12:59:22 -0400 Date: Thu, 23 Nov 2023 12:59:22 -0400 From: Jason Gunthorpe To: Robin Murphy Cc: Boris Brezillon , Joerg Roedel , iommu@lists.linux.dev, Will Deacon , linux-arm-kernel@lists.infradead.org, Rob Clark , Gaurav Kohli , Steven Price Subject: Re: [PATCH v2 0/2] iommu: Allow passing custom allocators to pgtable drivers Message-ID: <20231123165922.GB432016@ziepe.ca> References: <20231120140425.GA10140@ziepe.ca> <20231120153838.2166e7b8@collabora.com> <20231120144604.GD10140@ziepe.ca> <20231120161418.5eca178e@collabora.com> <20231120154536.GE10140@ziepe.ca> <6e74bd37-9e10-416e-9fbd-0cebb7948e2b@arm.com> <20231122175055.GI10140@ziepe.ca> <20231123095141.19dc26d6@collabora.com> <20231123134800.GA432016@ziepe.ca> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 23, 2023 at 04:49:21PM +0000, Robin Murphy wrote: > Oh, so essentially your plan is to replace io-pgtable-arm with something > else entirely. That's fair enough; happy to review that when I see it, but > as I pointed out, realistically this change hardly makes that any worse than > what's *already* present in io-pgtable-arm that you're going to have to deal > with anyway. > > I would instinctively assume that an "enterprise" optimised version would > want to be a clean-slate fork itself since I can't imagine it wants to be > burdened with having to handle non-coherent pagetables, Armv7 LPAE format, > or any of the quirks for embedded and mobile IOMMUs. I have no issue with > moving SMMUv3 to a shiny new pagetable implementation in future, but that is > quite clearly not at all incompatible with leaving the existing > implementation in place for all the *other* decidedly non-enterprise > io-pgtable-arm users, both IOMMU and GPU, not to mention GPU-via-IOMMU in > the case of Adreno. Oh, okay! Great, then we are all in agreement! I was not thinking about a fork, per-say, but yes I can see how that is would be a fine approach to take for everyone concerned. Thanks, Jason