Constraints Processing Order and Invalid Constraints - Constraints Processing Order and Invalid Constraints - 2026.1 English - UG903

Project Mode

Do the following before launching the wizard:

1. Specify a target XDC file with its PROCESSING_ORDER property set to NORMAL.
2. Ensure the target XDC file is part of the constraints set for the open design in memory.
3. Select the target XDC file in the constraints set.

The position of the target XDC file in the constraints set determines where the recommended constraints apply and save. The wizard reapplies invalid constraints from later XDC files. This ensures the most complete and accurate recommendations.

Example: The constraints set constr_1 contains three XDC files in this sequence: a.xdc, b.xdc, and c.xdc. If b.xdc is the target, the wizard applies recommended clocks. It then reapplies invalid constraints from c.xdc before identifying other missing constraints.

Non-project or DCP Modes

In these modes, you cannot specify a target XDC file. The wizard recommends and applies new constraints at the last position in the constraints sequence. This is equivalent to entering new constraints in the Tcl Console or through the Timing Constraints window.

The wizard does not attempt to reapply invalid constraints in these modes. Apply new constraints earlier to resolve dependencies or precedence issues by manually editing the sequence.

Editing Constraints Sequence Manually

1. Create new constraints in the Vivado Design Suite.
2. Run one of the following commands:
   • write_xdc -exclude_physical timing_constraints.xdc
   • write_xdc -type timing timing_constraints.xdc
3. Edit timing_constraints.xdc to move the new constraints higher in the file.
4. Save the file.
5. Run reset_timing.
6. Read the edited timing constraints file using the read_xdc timing_constraints.xdc command.
7. Review the updated sequence in the Timing Constraints window.
8. After review, save the sequence into the DCP.