f5ff79fddf
CONFIG_DMA_REMAP is used to build a few helpers around the core vmalloc code, and to use them in case there is a highmem page in dma-direct, and to make dma coherent allocations be able to use non-contiguous pages allocations for DMA allocations in the dma-iommu layer. Right now it needs to be explicitly selected by architectures, and is only done so by architectures that require remapping to deal with devices that are not DMA coherent. Make it unconditional for builds with CONFIG_MMU as it is very little extra code, but makes it much more likely that large DMA allocations succeed on x86. This fixes hot plugging a NVMe thunderbolt SSD for me, which tries to allocate a 1MB buffer that is otherwise hard to obtain due to memory fragmentation on a heavily used laptop. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
6.3 KiB
SPDX-License-Identifier: GPL-2.0-only
config NO_DMA bool
config HAS_DMA bool depends on !NO_DMA default y
config DMA_OPS depends on HAS_DMA bool
IOMMU drivers that can bypass the IOMMU code and optionally use the direct
mapping fast path should select this option and set the dma_ops_bypass
flag in struct device where applicable
config DMA_OPS_BYPASS bool
Lets platform IOMMU driver choose between bypass and IOMMU
config ARCH_HAS_DMA_MAP_DIRECT bool
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_SET_MASK bool
Select this option if the architecture needs special handling for
DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what
people thing of when saying write combine, so very few platforms should
need to enable this.
config ARCH_HAS_DMA_WRITE_COMBINE bool
Select if the architectures provides the arch_dma_mark_clean hook
config ARCH_HAS_DMA_MARK_CLEAN 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_PREP_COHERENT bool
config ARCH_HAS_FORCE_DMA_UNENCRYPTED bool
config SWIOTLB bool select NEED_DMA_MAP_STATE
config DMA_RESTRICTED_POOL bool "DMA Restricted Pool" depends on OF && OF_RESERVED_MEM && SWIOTLB help This enables support for restricted DMA pools which provide a level of DMA memory protection on systems with limited hardware protection capabilities, such as those lacking an IOMMU.
For more information see
<Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt>
and <kernel/dma/swiotlb.c>.
If unsure, say "n".
Should be selected if we can mmap non-coherent mappings to userspace.
The only thing that is really required is a way to set an uncached bit
in the pagetables
config DMA_NONCOHERENT_MMAP default y if !MMU bool
config DMA_COHERENT_POOL select GENERIC_ALLOCATOR bool
config DMA_GLOBAL_POOL select DMA_DECLARE_COHERENT bool
config DMA_DIRECT_REMAP bool select DMA_COHERENT_POOL select DMA_NONCOHERENT_MMAP
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 <kernel/dma/contiguous.c>.
If unsure, say "n".
if DMA_CMA
config DMA_PERNUMA_CMA bool "Enable separate DMA Contiguous Memory Area for each NUMA Node" default NUMA && ARM64 help Enable this option to get pernuma CMA areas so that devices like ARM64 SMMU can get local memory by DMA coherent APIs.
You can set the size of pernuma CMA by specifying "cma_pernuma=size"
on the kernel's command line.
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 2 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 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.
config DMA_MAP_BENCHMARK bool "Enable benchmarking of streaming DMA mapping" depends on DEBUG_FS help Provides /sys/kernel/debug/dma_map_benchmark that helps with testing performance of dma_(un)map_page.
See tools/testing/selftests/dma/dma_map_benchmark.c