When the persist option is set for BitGen, BitGen quits with the following error(s) and no bit file is generated:
"ERROR:BitGen:145 - Pin xx is a persistent pin, but a component exists in its IOB. Please rerun PAR with the persistent pins prohibited from use."
"ERROR:BitGen:157 - BitGen will terminate because of the above errors."
This problem has been fixed in the latest 6.2i Service Pack, available at:
http://support.xilinx.com/xlnx/xil_sw_updates_home.jsp
The first service pack containing the fix is 6.2i Service Pack 1.