The Virtex-6 ChipScope GTX IBERT Wizard PreEmphasis and PostEmphasis values do not match what is in Table 3-31 of the Virtex-6 FPGA GTX Transceivers User Guide (UG366).
What values should be used?
The values within Table 3-31 of the Virtex-6 FPGA GTX Transceivers User Guide (UG366) are what should be used. The register values shown in the IBERT GUI are correct. It is the dB values in the IBERT GUI that do not match up with what is in the user guide. Use the dB values in the user guide to match up to the register values in the IBERT GUI.
This issue has been fixed in ISE 13.3 design tools.