Placement Types - 2023.2 English

Vivado Design Suite User Guide: Using Constraints (UG903)

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2023.2 English

There are two types of placement in the tools:

  • Fixed Placement
  • Unfixed Placement

Fixed Placement

Fixed placement is placement specified by the user through one of the following:

  • Hand placement
  • An XDC constraint
  • Using either IS_LOC_FIXED or IS_BEL_FIXED on a cell object of the design loaded in memory.

Unfixed Placement

Unfixed placement is a placement performed by the implementation tools. By setting the placement as fixed, the implementation cannot move the constrained cells during the next iteration or during an incremental run. A fixed placement is saved in the XDC file, where it appears as a simple LOC or BEL constraint.

Promotes a LOC constraint from unfixed to fixed.
Promotes a BEL constraint from unfixed to fixed.