Should be set as the total number of threads that a given endpoint master device (which is connected to an SI slot) is capable of issuing.
This is the total internal width of ID signals propagated through the Crossbar switch.
This should be set according to this equation:
ceil_log2(NUM_SI) + max(THREAD_ID_WIDTH).
This is the value which the Crossbar assigns to each SI slot as a unique 'Master ID' to help route a request's response back to the SI slot that requested it.
This value is set automatically by the IP GUI and should take up the remaining ID bits between ID_WIDTH-THREAD_ID_WIDTH.
Note: The width of the *ID signals is (ID_WIDTH-1 downto 0).
You must take care that the bits between ID_WIDTH-THREAD_ID_WIDTH are NOT driven, as this can cause incorrect routing of requests and/or responses.