open inputs and Unisim libraries

Has anyone else seen problems with changes to the latest Xilinx 8.1 Unisim libraries?

I loaded up 8.1sp3 to do some S3E test code; structural code that worked fine with 6.x now chokes XST because the newer Unisim library lacks the default values needed to use 'open' on unused primitive inputs. ( e.g. BUFGMUX with only I1 in use )

Replacing all the "open"s with '0' works at the expense of a routed '0' net running around the chip.

Short of manually editing the Unisim library, or declaring all the primitives myself, anyone know of another workaround?

Brian

component BUFGMUX port ( O : out std_ulogic := '0'; I0 : in std_ulogic := '0'; I1 : in std_ulogic := '0'; S : in std_ulogic := '0' ); end component;

component BUFGMUX port ( O : out std_ulogic; I0 : in std_ulogic; I1 : in std_ulogic; S : in std_ulogic ); end component;