In addition to receiving configuration request packets, the
PCI Express Endpoint might receive TLP requests that are not processed within the PCI Express
hard block. Typical TLP requests received are Vendor Defined Messages and Read Requests.
Before stage 2 is loaded, TLP requests return unsupported requests (URs). After stage 2 has
been loaded, the mcap_design_switch output is asserted and TLP requests
function as defined by the user design.