AR# 44282

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13.2 XST - Derived constraints for MMCM are not taken into consideration during optimization

Description

XST derives constraints for MMCM output clocks, but it does not take the constraints into consideration when performing optimization.

Solution


XST is deriving the constraints for the outputs, but it is not taking the derived constraints into consideration when performing optimization which results in more logic paths. XST should be performing this automatically.

To work around the issue, put the derived constraints into an XCF file and this will force XST to optimize the design using the constraints.

A CR has been filed for better optimization using automatic derived constraints.
AR# 44282
Date 05/03/2012
Status Active
Type Known Issues
Tools
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