AR# 1073: PAR: "Number of GCLKS 5 out of 4" with Virtex Synplify netlist
PAR: "Number of GCLKS 5 out of 4" with Virtex Synplify netlist
Keywords: Synplify, Virtex, Par
General Description: Synplify will insert 4 global clock buffers on the signals with the highest fanout. However, if the design also contains a BUFGDLL, then PAR will error with a the number or GCLKS exceeding the available resources.
The problem exists with Synplify. The BUFGDLL cell is not counted as a BUFG resource and Synplify inserts another 4 BUFG or BUFGP cells violating the resource limit of 4 for Virtex.