ISSUES to be aware of (II)
TNM and PERIOD constraint cannot forward-trace through IBUF. TNM cannot forward-trace through BUFG either.
Use the “-u” switch with TRCE to report unconstrained paths (or Report Paths Not Covered In Timing Constraints for TA)
The -u will not necessarily contain every unconstrained path ( the static carry logic path in earlier schematic; STARTUP path). It essentially shows all “constrainable” unconstrained paths, such as paths that could have been reported with FROM:TO/PERIOD/OFFSET constraints.
Must apply to output net (of IBUF/BUFG) or use TNM_NET.