PAR reports the following over-capacity error for clock resource while the design does not exceed resource limitation:
"ERROR:XCad:225 - Errors encountered building the clock spines for Partial Reconfiguration. The errors below identify the clock regions that have over-capacity problems. To fix these problems you should either:
- reduce the number of clock networks within the Partitions identified by the failed Area Groups.
- modify the Area Group ranges to eliminate clock spine contention."
When the reconfiguration partition contains EMAC sites that are adjacent to the PPCs, PAR incorrectly computes the resource usage.
For ISE Design Suite 13.4, you can work around the problem by installing the attached patch and setting an environment variable "XIL_PR_NO_CLOCKSPINES": http://www.xilinx.com/txpatches/pub/swhelp/ise13_updates/ar_46672_pr_clk_spine_ise134.zip
In ISE Design Suite 14.1 and later, the environment variable still needs to be set, but no patch is required.