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Mon, 13 Jul 2026 05:00:54 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wjFLB-0000000Cu4e-38Ps; Mon, 13 Jul 2026 09:00:53 -0300 Date: Mon, 13 Jul 2026 09:00:53 -0300 From: Jason Gunthorpe To: Nick Hollinghurst Cc: Daniel Drake , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Broadcom internal kernel review list , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 4/6] iommu/generic_pt: Add Broadcom BCM2712 page table format Message-ID: <20260713120053.GE1835788@ziepe.ca> References: <20260712-bcm2712-iommu-submit-v1-0-80e10cdde2ea@reactivated.net> <20260712-bcm2712-iommu-submit-v1-4-80e10cdde2ea@reactivated.net> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Jul 13, 2026 at 11:02:15AM +0100, Nick Hollinghurst wrote: > Hi Daniel, > > On Sun, 12 Jul 2026 at 22:19, Daniel Drake wrote: > > > > The BCM2712 IOMMU implements a 2-level page table format. It is relatively > > simple, with one unusual aspect: leaf entries can only be installed at > > Level 0. > > I should admit that a single-level huge page mapping is possible, but > I was too lazy to implement it (and haven't much tested it). > > It can be done by setting bits 31, 30 and 28 of the top-level entry > (all other combinations of bits 31, 30 will point to a next-level > table). The page number is in 4K units but must be 4MB aligned. Let's do that instead of the weird full level contiguation page thing please Jason