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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 CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
(including software IOMMU). (including software IOMMU).
2) ARCH_KMALLOC_MINALIGN 2) ARCH_DMA_MINALIGN
Architectures must ensure that kmalloc'ed buffer is Architectures must ensure that kmalloc'ed buffer is
DMA-safe. Drivers and subsystems depend on it. If an architecture 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 isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in
the CPU cache is identical to data in main memory), 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 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. 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 constraints. You don't need to worry about the architecture data
alignment constraints (e.g. the alignment constraints about 64-bit alignment constraints (e.g. the alignment constraints about 64-bit
objects). objects).