The Serial RapidIO core might not be able to come out of initialization state. You may see the port_initialize signal getting asserted momentarily, but then never get reasserted. This issue is applicable to Virtex-4 devices only.
In SRIO v4.1, v4.2 and v4.3, there is a possibility that the core will go through reinitialization (and force a silent state) after port_initialized has been asserted.
This issue is fixed in SRIO v4.4 core delivered with IP Update 2 for ISE 10.1.