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| author | Robin Murphy <robin.murphy@arm.com> | 2021-03-05 17:32:34 +0100 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2021-03-18 10:55:23 +0100 |
| commit | 3542dcb15cef66c0b9e6c3b33168eb657e0d9520 (patch) | |
| tree | e8484ba2f056cd6ee5b1d042af44834136cb97cb /Documentation | |
| parent | iommu: Check dev->iommu in iommu_dev_xxx functions (diff) | |
| download | linux-3542dcb15cef66c0b9e6c3b33168eb657e0d9520.tar.xz linux-3542dcb15cef66c0b9e6c3b33168eb657e0d9520.zip | |
iommu/dma: Resurrect the "forcedac" option
In converting intel-iommu over to the common IOMMU DMA ops, it quietly
lost the functionality of its "forcedac" option. Since this is a handy
thing both for testing and for performance optimisation on certain
platforms, reimplement it under the common IOMMU parameter namespace.
For the sake of fixing the inadvertent breakage of the Intel-specific
parameter, remove the dmar_forcedac remnants and hook it up as an alias
while documenting the transition to the new common parameter.
Fixes: c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/7eece8e0ea7bfbe2cd0e30789e0d46df573af9b0.1614961776.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 04545725f187..835f810f2f26 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1869,13 +1869,6 @@ bypassed by not enabling DMAR with this option. In this case, gfx device will use physical address for DMA. - forcedac [X86-64] - With this option iommu will not optimize to look - for io virtual address below 32-bit forcing dual - address cycle on pci bus for cards supporting greater - than 32-bit addressing. The default is to look - for translation below 32-bit and if not available - then look in the higher range. strict [Default Off] With this option on every unmap_single operation will result in a hardware IOTLB flush operation as opposed @@ -1964,6 +1957,14 @@ nobypass [PPC/POWERNV] Disable IOMMU bypass, using IOMMU for PCI devices. + iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices. + Format: { "0" | "1" } + 0 - Try to allocate a 32-bit DMA address first, before + falling back to the full range if needed. + 1 - Allocate directly from the full usable range, + forcing Dual Address Cycle for PCI cards supporting + greater than 32-bit addressing. + iommu.strict= [ARM64] Configure TLB invalidation behaviour Format: { "0" | "1" } 0 - Lazy mode. |