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[2a02:3100:9c32:f801:9d9d:c89f:9fb1:4ec2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a015019e5asm8566915e9.2.2026.09.29.12.53.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 12:54:00 -0700 (PDT) Date: Tue, 29 Sep 2026 21:53:59 +0200 From: Karl Mehltretter To: Jason Gunthorpe , g@mbp-von-karl Cc: sashiko-bot@kernel.org, Gerd Hoffmann , Vivek Kasireddy , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] udmabuf: respect the device's maximum segment sizeg Message-ID: References: <20260929054835.94118-1-kmehltretter@gmail.com> <20260929060028.371041F00893@smtp.kernel.org> <20260929065601.99518-1-kmehltretter@gmail.com> <20260929120317.GH1616761@nvidia.com> Precedence: bulk X-Mailing-List: linux-media@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: <20260929120317.GH1616761@nvidia.com> On Tue, Sep 29, 2026 at 09:03:17AM +0100, Jason Gunthorpe wrote: > On Tue, Sep 29, 2026 at 08:56:01AM +0200, Karl Mehltretter wrote: > > Right, the misc device has no dma_parms, so it gets the 64K default and > > sync fails with 256K pages > > I would ignore this, it seems fictional to me, and if someone really > needs to support this rediculous combination it should be done inside > sg_alloc_table_from_pages_segment(:) > Fair enough, Sashiko got me there. Looking around, 256K pages seem to be barely supported today: they were already disabled for 47x, and I couldn't get userspace running on a 256K-page 44x kernel in QEMU. I'll leave v2 as is. Thanks for the review. Karl