I am trying to lock down the BUFR and BUFIO components in my Virtex-5 design, but I cannot find any valid sites. When is this going to be fixed?
To work around this issue, manually add the LOC constraints for those components to the UCF file.
This problem has been fixed in the latest 9.1i Service Pack available at:
http://www.xilinx.com/xlnx/xil_sw_updates_home.jsp
The first service pack containing the fix is 9.1i Service Pack 1.