Dear XhciDxe Maintainer,
I'm currently reviewing the XhciDxe driver and I'm trying to figure out how DMA
buffers are allocated. I see a number of pool and page allocations but I do
not see any called to PCI_IO Map()/Unmap() or to AllocateBuffer()/FreeBuffer().
This appears to be violating the rules for PCI DMA buffers since they are not
being mapped (and if common buffers are desired then they are also not being
allocated with AllocateBuffer as required).
Can someone more familiar with XHCI help me determine which buffers need to be
mapped and how (BusMasterRead, BusMasterWrite, CommonBuffer)?
It would be useful if we had a test environment that could catch driver DMA
buffer mapping issues earlier. I think one way to do this would be set up the
MMU in a non-identity mode so that anyone trying to use a processor virtual
address for DMA would see a failure.
Thanks,
Eugene
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