Messages in this thread | | | Date | Thu, 20 Jul 2017 10:19:10 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2 1/2] vfio: Allow No-IOMMU mode without checking iommu_present() |
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On Thu, Jul 20, 2017 at 10:02:33AM +0530, Anup Patel wrote: > Not allowing No-IOMMU mode for devices already having > iommu_ops on their bus is very conservative. > > We now have IOMMU (such as ARM SMMU) which can bypass > transcations when IOMMU is not configured for a given > device. In addition, it is not necessary to have all > devices on bus to be upstream to an IOMMU on that bus.
How does the SMMU know to bypass in these cases? As I explained before, the driver-specific command line option is the wrong way to go about arranging this.
Will
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