WARNING: Pack:2515 - LUT-1 inverter failed to join the OLOGIC comp matched to output buffer

So yea, I do some work with Dev Boards for my research projects.

I ran into this frustrating warning:


WARNING:Pack:2515 - The LUT-1 inverter
   "fmc_imageov_dvi_out_0/fmc_imageov_dvi_out_0/dvi_reset_n_t1_INV_0" failed to
   join the OLOGIC comp matched to output buffer
   "fmc_imageov_dvi_out_0/fmc_imageov_dvi_out_0/OBUFT_dvi_reset_n".  This may
   result in suboptimal timing.  The LUT-1 inverter
   fmc_imageov_dvi_out_0/fmc_imageov_dvi_out_0/dvi_reset_n_t1_INV_0 drives
   multiple loads.

for multiple pins.

If you get this, you simply need to make sure you don't have any combinatorial logic in the T (enable signal obviously)

First saw something similar here:
http://forums.xilinx.com/t5/Implementation/Pack-2515-XST-kept-optimizing-my-output-enable/td-p/256978

 It really sounds like the enable function itself is not

coming from a register, but from combinatorial logic that can't be pushed into the IOB.  As long

as the output enable comes directly from a register, then pushing it into the IOB should work.

Just make the change and register the signal.