The IOBDELAY_VALUE is not set correctly by BitGen, and this results in IDELAY/ISERDES initializing incorrectly.
This issue will be resolved in the next service pack release.
To work around this problem for 7.1isp2, install the patch provided with the following link and follow the installation instructions in the README file.
After installing this patch, you may encounter a BitGen crash as shown below if your design relies on DCI. To work around this issue, use BitGen 7.1 SP3.
FATAL_ERROR:Bitgen:BsVirt4_Bfd.c:3070:18.104.22.168 - Invalid bit EN_DCI_SLAVE_DOWN
passed into dcipminfo Process will terminate. To resolve this error,
please consult the Answers Database and other online resources at
http://support.xilinx.com.If you need further assistance, please open a
Webcase by clicking on the "WebCase" link at http://support.xilinx.com
make: *** [implementation/system.bit] Error 1