AR# 10705: 3.1i Virtex-II PAR - PAR hangs while routing PWR/GND nets in a Virtex-II design.
AR# 10705
3.1i Virtex-II PAR - PAR hangs while routing PWR/GND nets in a Virtex-II design.
Description
Keywords: Virtex-II, PAR, PWR/GND, hang, route
Urgency: Standard
General Description: When implementing a Virtex-II design that contains both Virtex-II multipliers and 512x32 BlockRAM configurations, PAR may hang while trying to route the PWR or GND nets.
The problem is related to the fact that in Virtex-II hardware, BlockRAMs and multipliers share pins. The placer is incorrectly placing BlockRAM and Multipliers in conflicting locations, which leads to contention over routing resources. The existence of unroutable connections results in the apparent router hang.
Solution
This problem is scheduled to be fixed in the next 3.1i Service Pack available at: http://support.xilinx.com/support/techsup/sw_updates. The first service pack that will contain the fix is 3.1i Service Pack 7.