Out-of-Context Constraints - Out-of-Context Constraints - 2026.1 English - UG903

In designs using Dynamic Function eXchange (DFX), it is common to synthesize parts of the design in an out-of-context (OOC) approach. In this flow, some constraints apply only to OOC synthesis.

When synthesizing blocks OOC, define input boundary clocks. Add these definitions to an OOC XDC file.

In project mode, follow these steps:

1. Add the OOC XDC file to the project.
2. Set the file property to use the file for synthesis in out-of-context mode. For example:

   add_file constraints_ooc.xdc
   set_property USED_IN {synthesis out_of_context} [get_files constraints_ooc.xdc]

You can also set the OOC property on the XDC file through the graphical user interface (GUI) by editing the properties of constraints_ooc.xdc.

In non-project mode, read the OOC XDC file using the out-of-context mode option.

read_xdc -mode out_of_context constraints_ooc.xdc