IBERT andv1.8 of the Virtex-6 FPGA GTH TransceiverWizardarecurrently setting the SLICE_NOISE_CTRL_x attributesto incorrect values as follows:
SLICE_NOISE_CTRL_0_LANE01 => 5007h
SLICE_NOISE_CTRL_2_LANE01 => EFFFh
SLICE_NOISE_CTRL_2_LANE23 => EFFFh
Updating these attributes to the correct values (as shown below) may provide a potential upside to the RX margin on some heavily utilized designs but majority of the designs will see no impact.However, it is still recommended to update these attributes to the correct settings and updating them should not result in any negative impact.This has been updated in the Virtex-6 GTH Transceiver wizard and IBERT in ISE 13.2 release.
SLICE_NOISE_CTRL_0_LANE01 => 0000h
SLICE_NOISE_CTRL_2_LANE01 => 7FFFh
SLICE_NOISE_CTRL_2_LANE23 => 7FFFh