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AR# 36315

ISE Place - ERROR:Place:1120 - Big block initial random placer cannot find solution


ISE reports the following error during MAP, however MAP does not stop but continues to run.

ERROR:Place:1120 - Big block initial random placer cannot find solution. This is due to design being over constrained by user specified or clock region constraints. Try locking down the big blocks to improve this condition.

What is the problem?


The term "Big Block" refers to large IP blocks such as block RAM, DSPs, etc.
The error message is an indication that the placer is having trouble finding an initial placement for the large IP blocks, i.e., there is a fitting failure associated with the big blocks in the design.

This error does not cause the placer to exit immediately, it will continue to attempt to fit the design while using different strategies.

This error is an early indication that the design might ultimately fail to place successfully (Place:543) and may experience long run times before finally failing.

Other than high utilization of the big blocks, the other things that can contribute to this error are placement constraints.

These can either be user area group constraints, or the clock region constraints created by the clock placer to floorplan a design with a complex clock structure.

The eventual Place:543 error will identify the components that failed to place, which can provide insight into the constraints involved that are contributing to the failure.
AR# 36315
Date Created 01/25/2011
Last Updated 03/26/2015
Status Active
Type Error Message
  • ISE Design Suite - 12.1