AR# 73510

Constraints 18-5210 No constraints selected for write.

Description

I have a Vivado design that uses constraints during synthesis, but see the following Warning while running synthesis.

[Constraints 18-5210] No constraints selected for write.
Resolution: This message can indicate that there are no constraints for the design, or it can indicate that the used_in flags are set such that the constraints are ignored. This later case is used when running synth_design to not write synthesis constraints to the resulting checkpoint. Instead, project constraints are read when the synthesized design is opened.

What does this mean?

Solution

This message covers multiple conditions.

  1. There are no constraints assigned to the current Constraints Set.
  2. Constraints are assigned properly to the current Constraints Set.

With the second condition (2), the part of the message below is intended to detail how Vivado handles project mode constraints. 

"This later case is used when running synth_design to not write synthesis constraints to the resulting checkpoint. Instead, project constraints are read when the synthesized design is opened."

This description indicates that a project mode synthesis run reads in constraints, uses them, but does not save the constraints to the synthesized checkpoint at <project_name>.runs/synth_1/<project_name>.dcp.


The message is found in Vivado versions 2018.2 through 2019.2.

This message has been removed from the 2020.1 version of Vivado as it was found to be confusing.

AR# 73510
Date 07/15/2020
Status Active
Type General Article
Tools More Less