WARNING:HDLCompiler:89 (Black-Box)

ISE reports warning about components from its library (bufio2, bufg, ...). It turns out that the warning occurs because the components are declared in the files where they are instantiated. the declarations should be removed

WARNING:HDLCompiler:89 - "C:\local\jgomezco\WhiteRabbit\wr-cores\ip_cores\general-cores\modules\genrams\xilinx\gc_shiftreg.vhd" Line 25: remains a black-box since it has no binding entity.
WARNING:HDLCompiler:89 - "C:\local\jgomezco\WhiteRabbit\wr-cores\platform\xilinx\wr_gtp_phy\wr_gtp_phy_spartan6.vhd" Line 246: remains a black-box since it has no binding entity.
WARNING:HDLCompiler:89 - "C:\local\jgomezco\WhiteRabbit\wr-cores\platform\xilinx\wr_gtp_phy\wr_gtp_phy_spartan6.vhd" Line 240: remains a black-box since it has no binding entity.