What happens if I target a Virtex-II device and use a RAMB4 primitive?
When a Virtex-II device is targeted and the RAMB4 primitive is used, the following warning message is reported:
"WARNING: MapLib:240 - Virtex BlockRAM RAMB4_S16_S16 symbol "mt_1" (output signal=dct_1d_tr_mt_1<0>) is being retargeted to Virtex2 BlockRAM. This will waste 75% of the Virtex2 BlockRAM capacity. To obtain better utilization, please re-run memory generator to retarget to Virtex2 BlockRAM modules."
This is a valid warning message; it indicates that block RAM is not being used optimally.