General Description: XST does not recognize IBUF_LVDS, IBUF_LVPECL, OBUF_LVDS, OBUF_LVPECL, IOBUF_LVDS and IOBUF_LVPECL as valid primitves. If you try to instantiate the LVDS buffers, XST will insert I/O buffers. When the design is run through the implementation tools, errors such as the following occur:
ERROR:NgdBuild:455 - logical net "xxxx" has multiple drivers