Documentation/DMA-API-HOWTO: add ARCH_KMALLOC_MINALIGN description
Add ARCH_KMALLOC_MINALIGN description in "Platform Issues" section. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: "David S. Miller" <davem@davemloft.net> Cc: Matt Mackall <mpm@selenic.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Родитель
4ae9ca825e
Коммит
2fd74e25df
|
@ -738,7 +738,20 @@ to "Closing".
|
|||
CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
|
||||
(including software IOMMU).
|
||||
|
||||
2) More to come...
|
||||
2) ARCH_KMALLOC_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
|
||||
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
|
||||
constraints. You don't need to worry about the architecture data
|
||||
alignment constraints (e.g. the alignment constraints about 64-bit
|
||||
objects).
|
||||
|
||||
Closing
|
||||
|
||||
|
|
Загрузка…
Ссылка в новой задаче