Version 8.1i of ReportGen has a new feature (-clock_regions) that provides a report of the clock region resource utilization. I have noticed that for certain clock regions, the utilization seems incorrect. For example, I have a design with an unrouted global clock, but the clock region report does not list any clock regions with more than eight clocks. What is the problem here?
There are three known problems with the clock region report:
1. The tools incorrectly calculate the clock region used by PPC and EMAC sites.
2. The report only counts clock nets and does not account for global resources used by S/R nets.
3. The report does not count global resources used to drive DCM CLKIN and CLKFB pins.
The first problem will be fixed in version 8.2i. The other two problems are being investigated for a later fix.