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Or is that not a use case > at all? Then it will correctly fail here because it is not implemented. This protects accidently copying what should have been private data into shared memory. If someone ever needs this they will have to implement a swiotlb pool for private memory along side the shared pool. But a device that can't reach all of private wont' be able to reach shared either, so it is basically fully broken, don't do that. The VMM Should be setting the address layout of the VM so that the devices it installs 'fit' within their addressing constraints. ie do not create a VM with a 52 bit address space when your device only supports 48. Jason