The data sheet on the XAUI lounge currently indicates that Virtex-4 (4VFX20 or larger) is supported and the data sheet in COREGen states that just 4VFX60 is supported. Which is correct?
The XAUI Core v6.1 has currently only been tested in hardware on Virtex-4 FX60, and this is why FX60 was specified in the data sheet. However, there should be no reason why the XAUI Core cannot be used in all of the Virtex-4 devices. This includes the smaller FX20 and FX40 devices. The data sheet on the XAUI lounge has been updated to reflect this.