In memory mapped DMA operations, both the source and destination of the DMA are memory mapped space. In an H2C transfer, the source address belongs to PCIe address space while the destination address belongs to AXI MM address space. In a C2H transfer, the source address belongs to AXI MM address space while the destination address belongs to PCIe address space. PCIe-to-PCIe, and AXI MM-to-AXI MM DMAs are not supported. Aside from the direction of the DMA, transfer H2C and C2H DMA behave similarly and share the same descriptor format.