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([2001:df0:0:200c:b411:35d2:9458:bbe5]) by smtp.gmail.com with ESMTPSA id q13-20020a170902a3cd00b0016403cae7desm13907355plb.276.2022.06.30.12.21.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jun 2022 12:22:03 -0700 (PDT) Message-ID: Date: Fri, 1 Jul 2022 07:21:53 +1200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 3/3] arch/*/: remove CONFIG_VIRT_TO_BUS Content-Language: en-US To: Christoph Hellwig References: <20220617125750.728590-1-arnd@kernel.org> <20220617125750.728590-4-arnd@kernel.org> <6ba86afe-bf9f-1aca-7af1-d0d348d75ffc@gmail.com> <9289fd82-285c-035f-5355-4d70ce4f87b0@gmail.com> <9f812d3d-0fcd-46e6-6d7e-6d4bf66f24ab@gmail.com> From: Michael Schmitz In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marek Szyprowski , Linux-Arch , scsi , Geert Uytterhoeven , Jakub Kicinski , Arnd Bergmann , Miquel van Smoorenburg , Denis Efremov , linux-m68k , John Paul Adrian Glaubitz , Khalid Aziz , Arnd Bergmann , Parisc List , Robin Murphy , Matt Wang , Linux Kernel Mailing List , Mark Salyzyn , Linux IOMMU , alpha , linuxppc-dev , "Maciej W . Rozycki" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Christoph, On 29/06/22 18:21, Christoph Hellwig wrote: > On Wed, Jun 29, 2022 at 11:09:00AM +1200, Michael Schmitz wrote: >> And all SCSI buffers are allocated using kmalloc? No way at all for user >> space to pass unaligned data? > Most that you will see actually comes from the page allocator. But > the block layer has a dma_alignment limit, and when userspace sends > I/O that is not properly aligned it will be bounce buffered before > it it sent to the driver. That limit is set to L1_CACHE_BYTES on m68k so we're good here. Thanks,     Michael