The NoC generally uses the Single Slave per ID (SSID) rule for write requests, but the HBM_NMU implementation allows three different types of write ordering to choose from:
- This type of write request must follow the SSID rule. It ensures the NMU receives the write response from one NSU before issuing a new write request to another NSU, when both the requests have the same AXI ID and a different destID.
- This write ordering rule requires the write requests with the same AXI ID to have their responses returned in the same order as the requests as well; however, the NMU will not block a new write request. It will be sent out immediately.
- This write ordering rule flushes all previous relaxed write order requests from the same AXI ID. It follows the SSID rule for other types of previous write order requests (strict/doorbell), in which case it ensures the NMU receives the write response for one NSU before issuing a new write request to another NSU, when both the requests have the same AXI ID and different destID.
Note: The other versions of the NMUs allow only Strict Order.