Fixed and Unfixed Logic - 2023.2 English

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)

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2023.2 English

The AMD Vivado™ tools track two different types of placement:

  • Elements placed by the user (shown in orange) are Fixed.
    • Fixed logic is stored in the XDC.
    • Fixed logic normally has a LOC constraint and might have a BEL constraint.
  • Elements placed by the tool (shown in blue) are Unfixed.

In the following figure, the I/O and block RAM placement is Fixed. The slice logic is Unfixed.

Figure 1. Fixed and Unfixed Placement