AR# 11499


3.1i Virtex-II PAR - Clock net not routed on global resources despite use of USELOWSKEWLINES constraint.


Keywords: clock, USELOWSKEWLINES, constraint, global, secondary, route

Urgency: Standard

General Description:
Cases have been seen where the router has pulled clock nets off the secondary global resources despite the use of the USELOWSKEWLINES constraint. This occurs when there are timing constraints that have not been met, and the router is attempting to find a better solution.


This problem is fixed in the latest 3.1i Service Pack, available at:
The first service pack containing the fix is 3.1i Service Pack 8.

The USELOWSKEWLINES constraint will now be considered a hard constraint so that the router will no longer attempt alternate solutions.
AR# 11499
Date 10/21/2008
Status Archive
Type General Article
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