This is an RFC patch set that adds support for configuring a default CMA size, depending on the platform.
At SUSE, our ARM installer image runs on a variety of platforms. One of these, the Raspberry Pi 3, requires CMA to be allocated on order to provide graphics output. Currently this can be done with the kernel's cma command- line parameter, or with a compile-time setting. The cma parameter requires user intervention during boot. Using a compile-time constant affects all platforms. So both options are undesireable. This patch set adds a data structure and look-up code to select a default CMA size, depending on the device's model name. The kernel's cma parameter or a compile-time setting take precedence of the per-device default. For the Raspberry Pi 3, the CMA allocator now reserves 64 MiB (out of 1 GiB) by default. We found that this is enough memory to run a graphics installer or a simple desktop environment under X11. Thomas Zimmermann (2): kernel/dma: Support device-specific CMA defaults kernel/dma: Default to 64 MiB of contiguous memory on Raspberry Pi 3 kernel/dma/contiguous.c | 62 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) -- 2.20.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
