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AR# 7241

2.1i Design Manager: MPPR is producing the same results for each new MPPR revision


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...



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 !


*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.


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

If the above situation occurs, please realize that the multiple
revisions created are identical to the first because timing
was met up front.

AR# 7241
Date 06/13/2002
Status Archive
Type General Article