When implementing SEM v3.4 IP in Vivado tools 2012.4, the tools will issue CRITICAL WARNINGs associated with the set_max_delay constraints in the example XDC, which are used to constrain the timing paths from the FRAME_ECC primitive to the SEM controller. The CRITICAL WARNINGs have the following form:
CRITICAL WARNING: [Constraints 18-515] set_max_delay: Path segmentation by forcing 'example_cfg/example_frame_ecc/SYNBIT' to be timing startpoint.
WARNING: [Constraints 18-613] set_max_delay: There will be no hold timing paths from this pin 'example_cfg/example_frame_ecc/SYNBIT' unless set_min_delay is used to constrain the paths.
These CRITICAL WARNINGs may be safely ignored. These CRITICAL WARNINGs are incorrectly issued by the tools, and it is not necessary to use the set_min_delay constraint on the path, or to take any further action.