Page 5 of the Virtex-4 FPGA Data Sheet: DC and Switching Characteristics data sheet (DS302) describes the following:
"VCCAUX and VCCO can power on at any ramp rate. Power supplies can be turned on in any sequence, though VCCAUX must powered on before or with VCCO for the specifications shown in Table 5. Xilinx does not specify the current when VCCAUX is not powered on first."
Several customers have asked, "What is the current if Vcco is powered first?"