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Sent: 08 September 2022 09:08
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git (AMD-Xilinx) <git@xxxxxxx>
Subject: Re: [RFC PATCH v3 4/7] bus/cdx: add cdx-MSI domain with gic-its
domain as parent
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OK, so you definitely need a mapping, but it cannot be a translation, and it
needs to be in all the possible address spaces. OMG.
Could you elaborate why it needs to be in all the possible address spaces? I'm in no way familiar with kernel IOVA allocation, so not sure I understand this requirement. Note that each CDX device will have its own unique StreamID (in general case, equal to DeviceID sent to the GIC), so, from a SMMU perspective, the mapping can be specific to that device. As long as that IOVA is not allocated to any DMA region for _that_ device, things should be OK? But, I appreciate it might not be that simple from a kernel perspective.