Why does the chipscope_icon_v1.02a use BUFGs even though I set use_bufg = false?
There is a bug in the Tcl code supplied with the ChipScope Icon core. To work around this issue, use the opposite of what is intended. If no BUFGs are wanted, set the parameter to true. If BUFGs are desired, the use_bufg parameter should be set to false.