If unsure, say N here.
+choice
+ prompt "IOMMU default DMA mode"
+ depends on IOMMU_API
config INTEL_IOMMU
depends on PCI_MSI && ACPI && (X86 || IA64)
config AMD_IOMMU
depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE
config ARM_SMMU_V3
depends on ARM64
"depends on ARM_SMMU_V3 || INTEL_IOMMU || AMD_IOMMU" may need to be added,
because it doesn't work on other platforms.
or "depends on X86 || IA64 || X86_64 || ARM64"
I suppose so. But I don't think that any other archs use the value from
iommu_dma_strict anyway.
+
+ default IOMMU_DEFAULT_STRICT
+ help
+ This option allows an IOMMU DMA mode to be chosen at build time, to
+ override the default DMA mode of each ARCH, removing the need to
+ pass in kernel parameters through command line. It is still possible
+ to provide ARCH-specific or common boot options to override this
+ option.
+
+ If unsure, keep the default.
+
+config IOMMU_DEFAULT_LAZY
+ bool "lazy"
+ help
+ Support lazy mode, where for every IOMMU DMA unmap operation, the
+ flush operation of IOTLB and the free operation of IOVA are deferred.
+ They are only guaranteed to be done before the related IOVA will be
+ reused.
+
+config IOMMU_DEFAULT_STRICT
+ bool "strict"
+ help
+ For every IOMMU DMA unmap operation, the flush operation of IOTLB and
+ the free operation of IOVA are guaranteed to be done in the unmap
+ function.
+
+ This mode is safer than the two above, but it maybe slower in some
+ high performace scenarios.
+
+endchoice
+
config OF_IOMMU
def_bool y
depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 966426a96520..177b0dafc535 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
static DEFINE_IDA(iommu_group_ida);
static unsigned int iommu_def_domain_type __read_mostly;
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly =
+ IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
Currently, a maximum of 100 columns are allowed in a row.
Sure, but some people still prefer limiting to 80, and codingstyle
doc mentions a preference for 80.
But if you really think I should change, then that's ok.
Thanks,
John
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