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Commit ce00f7fe authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Linus Torvalds
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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
a6eb9fe1).

ARCH_DMA_MINALIGN must be defined instead of ARCH_KMALLOC_MINALIGN to
ensure that kmalloc'ed buffer is DMA-safe.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b171aa27

Documentation/DMA-API-HOWTO.txt

+3 −3
Original line number Original line Diff line number Diff line
@@ -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).