3. Register Map and Address Spaces
The DMA AFU supports two memory views: The DMA view and the host view.
The DMA view supports a 50-bit address space. The lower half of the DMA view maps to the FPGA device memory and the magic number ROM inside the DMA BBB. The upper half of the DMA view maps to the host memory which is split into a direct access and a write fence region. The direct access and memory write fence regions overlaps into the same 48-bit host physical address space.
The host view includes all the registers accessible through MMIO accesses such as the DFH tables, and the control/status registers of the various IP cores used inside the DMA AFU. The host view includes an indirect mapping mechanism to the device memory so that the host can access the FPGA device memory using a 4KB windowing mechanism built into the DMA BBB.
The MMIO registers in the DMA BBB and AFU support 32- and 64- bit access. The DMA AFU does not support 512-bit MMIO accesses. Accesses to the MSGDMA registers inside the DMA BBB must be 32 bits.
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