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AR# 64967

2013.4 - No Warning/Critical warning is reported when register with IOB=TRUE property fails to be packed into IOB


I set IOB = TRUE for both registers driving the OBUFT in XDC.

Since the reset signal of both registers are different, these two registers cannot be packed into IOB at the same time.

The implementation tool's behavior is correct, but there is no Warning/Critical warning issued to remind me that one of the registers failed to be packed into IOB and indicate the root cause for it.


The following new DRC message has been added for Vivado 2015.3:

WARNING: [DRC 23-20] Rule violation (AVAL-250) OBUFT_has_two_IOB_FFs_with_reset_diff - The OBUFT OBUFT_inst has I (data) pin driven by Flop data_reg and T (tri-state) pin driven by Flop T_reg, both of which have the IOB attribute set, but have different reset signals. This cannot be supported in this device architecture.

AR# 64967
Date 07/31/2015
Status Active
Type General Article
  • Vivado Design Suite - 2013.4
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