Zero-length Writes

The AXI slave can initiate a zero-length memory write transaction in the same way as a 1-byte memory write transaction, except the byte valid bits in MASTER_AXI_WSTRB are all set to zero during the data cycle. The PCIe Controller sends a memory write request on the PCIe link with the length field set to one double word, and the byte-enable fields set to all zeroes.