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AR# 63499

2014.4 Vivado Placement - Design that worked with the SSI_SpreadSLLs directive in 2014.2 no longer works in later revisions.


My XC7V2000TFLG1925-1 design runs successfully using the directive SSI_SpreadSLLs in Vivado 2014.2 but fails in all later versions.

What has happened so that this directive no longer works with my design?

Phase 3 Global Placement
WARNING: [Place 30-594] The best SLR partitions found by the placer requires 20118 Super Long Lines (SLLs) out of 13720 for the crossing of SLR# 0 to SLR# 1 boundary.
ERROR: [Place 30-441] A placement could not be found which does not exceed the number of Super Long Lines (SLLs), 13720, for this device, resulting in an unroutable situation.
Resolution: It is suggested to do one or more of the following techniques to try to alleviate this situation:
1. Use a synthesis methodology that limits resource sharing across related hierarchies:
a. Prevent cross-boundary optimization on the complete design (synthesis option) or on specific hierarchical modules (attribute or constraint) b. Bottom-up synthesis (Out-Of-Context, partitions) c. Disable Resource Sharing and/or Equivalent Register Removal 2. Limit the use of high fanout nets in the design 3. Reevaluate pin placement for the design 4. Manually assign resources to Super Logic Regions (SLRs) ensuring connectivity is less than the maximum (define one pblock per SLR) Phase 3 Global Placement | Checksum: 206a5a441
Steps To Reproduce   
This script runs placer with SSI_SpreadSLLs directive


The SSI_SpreadSLLs directive went through a major change from 2014.2 to 2014.3.

Some of those changes include much more aggressive optimization of SLR partitioning.

As a result, it is not expected that every design will pass with that directive even if it passes with the default directive.

For this design the SSI_SpreadSLLs directive should not be used.
AR# 63499
Date 02/16/2015
Status Active
Type General Article
  • Virtex-7
  • Vivado Design Suite
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