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[94.254.104.176]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59e5f89a356sm5443917e87.92.2026.02.19.12.55.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Feb 2026 12:55:50 -0800 (PST) From: Magnus Lindholm To: richard.henderson@linaro.org, mattst88@gmail.com, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, linux-doc@vger.kernel.org Cc: glaubitz@physik.fu-berlin.de, macro@orcam.me.uk, macro@redhat.com, mcree@orcon.net.nz, ink@unseen.parts, Magnus Lindholm Subject: [PATCH 0/1] alpha: enable DMA CMA support (HAVE_DMA_CONTIGUOUS) Date: Thu, 19 Feb 2026 21:53:48 +0100 Message-ID: <20260219205514.4434-1-linmag7@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series enables CONFIG_DMA_CMA support on Alpha by selecting HAVE_DMA_CONTIGUOUS and wiring up the required architecture hooks. Alpha previously relied solely on high-order page allocator allocations for coherent DMA buffers. With memory compaction now functional, CMA can be safely enabled to provide reliable physically contiguous allocations under fragmentation. Testing was performed on an Alpha UP2000+ (SMP) and a DS10 (UP) using a custom kernel module that verified the following: - Correct CMA reservation via "cma=64M" - CmaTotal/CmaFree reporting in /proc/meminfo - Successful 32 MiB dma_alloc_coherent() allocations - CmaFree reduction and recovery after free - Successful allocations under heavy memory load No allocation failures were observed. Magnus Lindholm (1): alpha: enable DMA CMA support (HAVE_DMA_CONTIGUOUS) .../io/dma-contiguous/arch-support.txt | 2 +- arch/alpha/Kconfig | 1 + arch/alpha/kernel/pci_iommu.c | 46 +++++++++++++++++++ arch/alpha/kernel/setup.c | 16 +++++++ 4 files changed, 64 insertions(+), 1 deletion(-) -- 2.52.0