The XAUI core v9.1rev1 is the last version totarget Virtex-6 GTX CES silicon. All later versions of the core support production silicon with production GTX attributes. If v9.1 of the XAUI is still being used, then the GTX POWER_SAVE attribute will need to be updated in order to use this version of the XAUI core in ISE 12.2 software and later. If using production silicon, please update to the latest version of the XAUI core.