I would like to instantiate a Xilinx device primitive in my design.
Where can I find information about the required ports and parameters/generics for the Xilinx primitives?
This information can be found in the Libraries Guide for a given device and design entry method. HDL-based designs have a document called the "Libraries Guide for HDL Designs", while schematic-based designs have a document called the "Libraries Guide for Schematic Designs.
These documents contain a listing of all instantiatable Xilinx primitives as well as their associated ports and parameters/generics.
In Project Navigator, select Help -> "Software Manuals" and expand the "Libraries Guides" menu to see the Device family specific libraries guides.