I cannot generate a x8 Block Plus core targeting a Virtex-5 LX30T device. Why?
The Virtex-5 LX30T is offered in two packages, but the FF323 package only contains four transceivers (2 GTP_DUALs). An eight lane implementation in the Virtex-5 LX30T is only supported in the FF665 package, which contains eight transceivers (4 GTP_DUALs). Currently, CORE Generator does not allow you to generate an eight lane core when targeting the XC5VLX30TFF665-1. Eight lane support will be added in v1.8, which is scheduled for IP Update #2 for 10.1.
To work around this issue, generate a x8 core targeting a LX50T-1FF665 device and use the UCF provided below.
You can download the eight lane UCF for the XC5VLX30T-1FF665 at:
05/07/2008 - Initial Release