This issue is fixed in the latest 8.1i Service Pack, available at:
http://www.xilinx.com/xlnx/xil_sw_updates_home.jspThe first service pack containing the fix is 8.1i Service Pack 1.
This is a problem in the simulation models.
There is also a patch available for this model at:
http://www.xilinx.com/txpatches/pub/swhelp/ise7_updates/cr221551.tar.gzInstructions for patch:
Date: Nov 22nd, 2005
File Name: cr221551.tar.gz
Description: Patched BUFGCTRL and BUFR to remove the 100 ps delay as noted in CR 221551
Platform: ALL
Applicable Software version: 7.1i Service Pack 4.
Installation/Use:
Extract the archived file as shown below:
PC :
Use any unzip utility to unarchive this file.
Make a backup of the "simprims" directory in the XILINX installation directory, prior to extracting this file.
Extract these files to the XILINX installation directory.
Once the files have been extracted, re-run CompXLib to ensure that these are the files being used.
Unix / Linux:
Make a backup of the "simprims" directory under the "$XILINX" tree
Type the following:
>gunzip cr221551.tar.gz
>tar -C $XILINX -xvf cr221551.tar
Once the files have been extracted, re-run CompXLib to ensure that these are the files being used.
Testing:
Once this is complete, test out the design that failed to work. It should work correctly.