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Documentation: DMA-API-HOWTO.txt: rename ARCH_KMALLOC_MINALIGN to ARCH_DMA_MINALIGN

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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:
FUJITA Tomonori 2010-08-14 16:36:17 +09:00 committed by Linus Torvalds
parent b171aa2770
commit ce00f7feb0
1 changed files with 3 additions and 3 deletions
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6
Documentation/DMA-API-HOWTO.txt
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@ -738,17 +738,17 @@ to "Closing".
CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
(including software IOMMU).
2) ARCH_KMALLOC_MINALIGN
2) ARCH_DMA_MINALIGN
Architectures must ensure that kmalloc'ed buffer is
DMA-safe. Drivers and subsystems depend on it. If an architecture
isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in
the CPU cache is identical to data in main memory),
ARCH_KMALLOC_MINALIGN must be set so that the memory allocator
ARCH_DMA_MINALIGN must be set so that the memory allocator
makes sure that kmalloc'ed buffer doesn't share a cache line with
the others. See arch/arm/include/asm/cache.h as an example.
Note that ARCH_KMALLOC_MINALIGN is about DMA memory alignment
Note that ARCH_DMA_MINALIGN is about DMA memory alignment
constraints. You don't need to worry about the architecture data
alignment constraints (e.g. the alignment constraints about 64-bit
objects).