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Documentation: DMA-API-HOWTO.txt: rename ARCH_KMALLOC_MINALIGN to ARCH_DMA_MINALIGN
ARCH_KMALLOC_MINALIGN was renamed to ARCH_DMA_MINALIGN (the commit
a6eb9fe105
).
ARCH_DMA_MINALIGN must be defined instead of ARCH_KMALLOC_MINALIGN to
ensure that kmalloc'ed buffer is DMA-safe.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
b171aa2770
commit
ce00f7feb0
@ -738,17 +738,17 @@ to "Closing".
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CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
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(including software IOMMU).
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2) ARCH_KMALLOC_MINALIGN
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2) ARCH_DMA_MINALIGN
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Architectures must ensure that kmalloc'ed buffer is
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DMA-safe. Drivers and subsystems depend on it. If an architecture
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isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in
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the CPU cache is identical to data in main memory),
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ARCH_KMALLOC_MINALIGN must be set so that the memory allocator
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ARCH_DMA_MINALIGN must be set so that the memory allocator
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makes sure that kmalloc'ed buffer doesn't share a cache line with
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the others. See arch/arm/include/asm/cache.h as an example.
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Note that ARCH_KMALLOC_MINALIGN is about DMA memory alignment
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Note that ARCH_DMA_MINALIGN is about DMA memory alignment
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constraints. You don't need to worry about the architecture data
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alignment constraints (e.g. the alignment constraints about 64-bit
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objects).
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