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config HAS_DMA
bool
depends on !NO_DMA
default y
config NEED_SG_DMA_LENGTH
bool
config NEED_DMA_MAP_STATE
bool
config ARCH_DMA_ADDR_T_64BIT
def_bool 64BIT || PHYS_ADDR_T_64BIT
config ARCH_HAS_DMA_COHERENCE_H
bool
config ARCH_HAS_DMA_SET_MASK
bool
config DMA_DECLARE_COHERENT
bool
config ARCH_HAS_SETUP_DMA_OPS
bool
config ARCH_HAS_TEARDOWN_DMA_OPS
bool
config ARCH_HAS_SYNC_DMA_FOR_DEVICE
bool
config ARCH_HAS_SYNC_DMA_FOR_CPU
bool
select NEED_DMA_MAP_STATE
config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
bool
config ARCH_HAS_DMA_COHERENT_TO_PFN
bool
config ARCH_HAS_DMA_MMAP_PGPROT
bool
config DMA_NONCOHERENT_CACHE_SYNC
bool
config DMA_VIRT_OPS
bool
depends on HAS_DMA
config SWIOTLB
bool
select NEED_DMA_MAP_STATE
config DMA_REMAP
depends on MMU
select GENERIC_ALLOCATOR
bool
config DMA_DIRECT_REMAP
bool
select DMA_REMAP
config DMA_CMA
bool "DMA Contiguous Memory Allocator"
depends on HAVE_DMA_CONTIGUOUS && CMA
help
This enables the Contiguous Memory Allocator which allows drivers
to allocate big physically-contiguous blocks of memory for use with
hardware components that do not support I/O map nor scatter-gather.
You can disable CMA by specifying "cma=0" on the kernel's command
line.
For more information see <include/linux/dma-contiguous.h>.
If unsure, say "n".
if DMA_CMA
comment "Default contiguous memory area size:"
config CMA_SIZE_MBYTES
int "Size in Mega Bytes"
depends on !CMA_SIZE_SEL_PERCENTAGE
default 0 if X86
default 16
help
Defines the size (in MiB) of the default memory area for Contiguous
Memory Allocator. If the size of 0 is selected, CMA is disabled by
default, but it can be enabled by passing cma=size[MG] to the kernel.
config CMA_SIZE_PERCENTAGE
int "Percentage of total memory"
depends on !CMA_SIZE_SEL_MBYTES
default 0 if X86
default 10
help
Defines the size of the default memory area for Contiguous Memory
Allocator as a percentage of the total memory in the system.
If 0 percent is selected, CMA is disabled by default, but it can be
enabled by passing cma=size[MG] to the kernel.
choice
prompt "Selected region size"
default CMA_SIZE_SEL_MBYTES
config CMA_SIZE_SEL_MBYTES
bool "Use mega bytes value only"
config CMA_SIZE_SEL_PERCENTAGE
bool "Use percentage value only"
config CMA_SIZE_SEL_MIN
bool "Use lower value (minimum)"
config CMA_SIZE_SEL_MAX
bool "Use higher value (maximum)"
endchoice
config CMA_ALIGNMENT
int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
range 4 12
default 8
help
DMA mapping framework by default aligns all buffers to the smallest
PAGE_SIZE order which is greater than or equal to the requested buffer
size. This works well for buffers up to a few hundreds kilobytes, but
for larger buffers it just a memory waste. With this parameter you can
specify the maximum PAGE_SIZE order for contiguous buffers. Larger
buffers will be aligned only to this specified order. The order is
expressed as a power of two multiplied by the PAGE_SIZE.
For example, if your system defaults to 4KiB pages, the order value
of 8 means that the buffers will be aligned up to 1MiB only.
If unsure, leave the default value "8".
endif
config DMA_API_DEBUG
bool "Enable debugging of DMA-API usage"
select NEED_DMA_MAP_STATE
help
Enable this option to debug the use of the DMA API by device drivers.
With this option you will be able to detect common bugs in device
drivers like double-freeing of DMA mappings or freeing mappings that
were never allocated.
This also attempts to catch cases where a page owned by DMA is
accessed by the cpu in a way that could cause data corruption. For
example, this enables cow_user_page() to check that the source page is
not undergoing DMA.
This option causes a performance degradation. Use only if you want to
debug device drivers and dma interactions.
If unsure, say N.
config DMA_API_DEBUG_SG
bool "Debug DMA scatter-gather usage"
default y
depends on DMA_API_DEBUG
help
Perform extra checking that callers of dma_map_sg() have respected the
appropriate segment length/boundary limits for the given device when
preparing DMA scatterlists.
This is particularly likely to have been overlooked in cases where the
dma_map_sg() API is used for general bulk mapping of pages rather than
preparing literal scatter-gather descriptors, where there is a risk of
unexpected behaviour from DMA API implementations if the scatterlist
is technically out-of-spec.
If unsure, say N.
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