On Thursday 25 February 2016 13:26:17 Marek Szyprowski wrote:
+}
+extern void *arch_alloc_from_atomic_pool(size_t size, struct page **ret_page,
gfp_t flags);+extern bool arch_in_atomic_pool(void *start, size_t size); +extern int arch_free_from_atomic_pool(void *start, size_t size);
doesn't feel completely right yet. In particular the arch_flush_page() interface is probably still too specific to ARM/ARM64 and won't work that way on other architectures.
I think it would be better to do this either more generic, or less generic:
a) leave the iommu_dma_map_ops definition in the architecture specific code, but make it call helper functions in the drivers/iommu to do all of the really generic parts.
b) clarify that this is only applicable to arch/arm and arch/arm64, and unify things further between these two, as they have very similar requirements in the CPU architecture.
Some really generic parts are already in iommu/dma-iommu.c and one can build it's own, non-ARM CPU architecture based IOMMU/DMA-mapping code. Initially I also wanted to use that generic code on both ARM and ARM64, but it turned out that both archs, ARM and ARM64 will duplicate 99% of code, which use this 'generic' functions. This was the reason why I dedided to move all that common code from arch/{arm,arm64}/mm/dma-mapping.c to drivers/iommu/dma-iommu-ops.c
I'm not sure if I can design all the changes that need to be made to drivers/iommu/dma-iommu-ops.c to make it more generic. Maybe when one will try to use that code with other, non-ARM architecture based arch glue code, a better abstraction can be developed. For now I would like to keep all this code in a common place so both arm and arm64 will benefit from improvements done there.
Fair enough. Let's stay with your approach then.
Arnd