AR# 7241: 2.1i Design Manager: MPPR is producing the same results for each new MPPR revision
AR# 7241
2.1i Design Manager: MPPR is producing the same results for each new MPPR revision
Description
Keywords: 2.1i, MPPR, Multi-Pass Place and Route, revision, route, same results, identical
Urgency: Standard
General Description:
Running MPPR (Multi-Pass Place and Route) from the 2.1i Design Manager produces the following behavior:
MPPR will perform several PAR passes, however the results of the revisions created are all identical !
Two possible solutions are discussed below...
Solution
1
This particular issue will be resolved in a future release. The method described below should be used for the time being:
Check to see if you had a a routed revision highlighted prior to initiating MPPR. If so, what happened is that after running the PAR passes, the tools threw away the results of all the trials and replaced them with the original data !
Workaround: --------------------
*Select Design->New Revision to create a blank revision *Select Design->MPPR to initiate Multi-Pass Place and Route on the New revision.
If the above does not help, please reference (Xilinx Solution 5169) for additional suggestions.
2
Another possible reason for PAR passes to be identical....
When running MPPR targeting a Virtex device, the PAR tools will NOT go into running multiple cost algorithms if they can determine up front that the timing designated can be met. However, PAR will still go ahead and create the different revisions giving the impressions that unique results have been created.
If the above situation occurs, please realize that the multiple revisions created are identical to the first because timing was met up front.