General Description: When Coregen generates certain DSP modules, the result sometimes utilizes many more CLBs than specified in the datasheet for the specific Core.
This problem has been observed when Coregen is set to generate a symbol in Workview Office. The increase in CLB utilization is associated with the loss of RLOC properties generated by Coregen when the Viewlogic database is generated for the module.
If you are using Workview Office:
In Viewdraw, open up the symbol generated by Coregen in the Viewdraw symbol editor. Double click on the symbol for the Coregen block and click on the attribute tabs. The LEVEL attribute must be set to "XILINX".
If LEVEL=VHDL or something else, change it to LEVEL=XILINX.
Write out a new EDIF file and re-implement the design. The implementation of the new EDIF file should require much fewer CLBs than the previous one.