AXI ID Management

Read requests are split transactions; that is, the client may make additional read and write requests while the completion for a read request is pending. The client can issue each outstanding read request with the same MASTER_AXI_ARID or unique ones. The PCIe Controller can receive a maximum of 256 outstanding read requests. It internally maps the MASTER_AXI_ARID to an internally generated PCIe tag. The PCIe Controller looks up this mapping to translate an incoming completion to a corresponding MASTER_AXI_RID value sent with the read data channel.