This Answer Record discusses some of the limitations of the 11.3 tools with regard to the Virtex-6 FPGA HXT and GTH transceiver.
The HX255T FF1923 and HX380T FF1154 are in the product matrix, but are not in the tools.
This is correct and these part/package combinations will not be supported until the 11.4 release.
Is timing-driven simulation available in 11.3?
No, but it will be available in the 11.4 release.
Is BitGen supported for HXT devices?
Support is scheduled to be available in the 11.4 release.
How complete is the GTH User's Guide?
The GTH User Guide is incomplete with IDS 11.3 release, as there are neither PMA details nor board design details. These are scheduled to be added to the documentation with each new release of UG371.
Why has the Packaging and Pin-out documentation not been released?
The Packaging and Pin-out documentation is scheduled to be released shortly. Please refer to (Xilinx Answer 33485) for more information.
Where can I find the complete list of protocols which GTH will support?
The GTH Transceiver User's Guide (UG371) contains a list of supported protocols. Please keep in mind that support does not indicate compliance, which must rely on characterization data currently being generated.
The data sheet shows that there are -3 HXT parts, but they are not available in 11.3.
The data sheet does show -3 support and this is correct, but software will not support -3 for HXT until the 11.4 release.
What tools are available for the HXT parts?
XPE supports HXT devices with 11.3 for upfront Power Analysis.