Why does the Hard IP for PCI Express downtrain from Gen3 x8 to Gen3 x1 in simulation?

Description

Due to a problem in the Quartus II software version 12.1 and earlier, the Stratix V Hard IP for PCI Express testbench downtrains from Gen3 x8 to Gen3 x1.

This problem only affects simulation and does not cause any problems in hardware.

Resolution

To work around this problem upgrade to software v12.1SP1 or later.