Description
The Block RAM used in the Virtex-6 and Spartan-6 FPGA Serial RapidIO v5.4 Buffer Cores are set to READ_FIRST mode. If the buffer is clocked asynchronously, this violates the block RAM rules and could cause collisions in hardware.
Solution
The Virtex-6 and Spartan-6 FPGA Cores are pre-production in v5.4 and should not be used in production designs. All block RAM are switched to WRITE_FIRST mode starting in v5.4 Rev1. For more information, see
(Xilinx Answer 33312).