Based on the Xilinx support homepage;
the default voltage value of the VCCAUX pin should be 2.5-volts.
However, voltage value I mesured at the C7 pin was 3.3-volts.
Moreover, this voltage value didn't change even after I changed the voltage setting to be 2.5-volts, as "CONFIG VCCAUX=2.5;" in the UCF file.
Is there any specification of the XEM6010-LX150 PCB board not to allow 2.5-volt of the VCCAUX?