My Virtex-6 design fails during Bitgen with many instances of the following error. Is this a known problem and is there a workaround?
ERROR:Bitgen - Could not find programming information for I/O standard
DIFF_SSTL18_II_DCI drive=-1, slew=*, master=*. The programming of the output
buffers will not be correct.
This problem has been seen in a design that had a bi-directional differential I/O configuration constructed of an IBUFDS and two pairs of OSERDES/OBUFT symbols. The problem went away when an IOBUFDS was used instead. A CR has been filed to investigate the failure of the original circuit.
A separate issue has been seen with a similar failure mode. See (Xilinx Answer 35086).