System Management Network (SMN)

The System Management Network (SMN) is the system fabric outside the SMU. It carries transactions between the SMU and resources elsewhere in the chiplet. SEP, SMC and DTP belong to the SMU; the SMN is a separate platform component.

1. SMU Interface

The SMU exposes two AXI interfaces toward the SMN:

  • smu_axi_in_req_i / smu_axi_in_resp_o: external requests entering the SMU and their responses.

  • smu_axi_out_req_o / smu_axi_out_resp_i: requests leaving the SMU and responses from the external fabric.

The internal SMU crossbar connects SEP, SMC and these external interfaces. It routes incoming requests to the programmed SEP or SMC global aperture. SEP and SMC requests that match neither aperture leave through the external output. External requests cannot loop back to that output; an unmatched incoming address produces a decode error.

2. Addressing and Integration

SEP and SMC global base addresses and region sizes are software-programmed. The surrounding system must use the same address assignments when accessing those subsystems. Subsystem remapping and filtering are described in their Interconnect chapters, and the Programmer’s Guide gives the aperture programming sequence.

This chapter describes the SMU boundary. Network topology, routing beyond that boundary and connections to other chiplets depend on the enclosing system.