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AR# 60029

2014.1 - IBERT - Design fails with error [Place 30-642] Placement Validity Check : Failed to find legal placement

Description

Some IBERT Ultrascale GTH designs fail with the error below:

[Shape Builder 18-121] Failed to get a compatible bel element for instance IBUF of type IBUF.
[Shape Builder 18-121] Failed to get a compatible bel element for instance IBUF of type IBUF.
[Place 30-642] Placement Validity Check : Failed to find legal placement.


This issue is seen when the output of IBUFDS_GTE3 is not driving any logic.

Even though this logic is used in different combinations, failure is only seen in some cases, in other cases it will pass implementation and bit gen.

In the passing design the unused IBUFDS (instantiated and given pin lock constraints) are removed/optimized during implementation and in failing design the unused IBUFDS are not removed/optimized.

The behavior is not consistent across all designs.

Solution

There are two work-arounds for this issue.

Option 1

Select the QUAD that is in use. 

Add the attribute "(* don't_touch = "true" *)" on any unused IBUFDS_GTHE3 in example_design.v (the top example design file).

Option 2

If the IBUFDS_GTHE3 in use cannot be found, add the attribute "(* don't_touch = "true" *)" on all IBUFDS_GTHE3 in the "example top" HDL file.


AR# 60029
Date Created 03/31/2014
Last Updated 05/21/2014
Status Active
Type General Article
Devices
  • Kintex UltraScale