AR #32456 - 11.1 Timing Known Issue - MAXSKEW constraint shows a violation, but the report says it met timing
11.1 Timing Known Issue - MAXSKEW constraint shows a violation, but the report says it met timing
| AR# | 32456 |
| Topic | SW-Timing Analyzer/TRCE |
| Last Modified | 2009-04-20 00:00:00.0 |
| Status | Active |
Description
Keywords: skew, false, violation, meeting, failing
My MAXSKEW constraint shows a violation, but the report says it met timing.
Following is an example:
Timing constraint: NET "SDI_Ref_Clk1" MAXSKEW = 0.001 ns;
1 net analyzed, 1 failing net detected.
1 timing error detected.
Maximum net skew is 0.208ns.
--------------------------------------------------------------------------------
Slack: -0.207ns SDI_Ref_Clk1
Report: 0.208ns skew meets 0.001ns timing constraint by -0.207ns
From To Delay(ns) Skew(ns)
SLICE_X23Y59.X E7.O1 1.037 0.208
SLICE_X23Y59.X D7.O1 1.037 0.208
Solution
This is a known issue. Currently, the reports states:Report: 0.208ns skew meets 0.001ns timing constraint by -0.207ns
Xilinx is working to change it so that it correctly acknowledges a failing path and states that the path "fails" by X ns.