multiple configuration file in AP mode for cyclone III

Hi,

I am designing a board with cyclone III FPGA. I am planning to configure the FPGA in the AP mode.I want to store 4 copies of configuration file in the FLASH.. (assume its already stored)...

Now, i want to provide some external control such that the fpga should be able to configure itself from different files, based on the external control...

how can i do it ?

one solution what i got is mentioned below,

the default address what FPGA will through to get config file after reset in AP mode is 0X10000 h. Now, the configuration file size is 4.1Mbits. So i'll store 4 configuration files in locations starting at 010000h, 110000h, 210000h, 310000h. Now if i connect A20 & A21 of FLASH to jumpers instead of FPGA, i'll be able to control the file which the FPGA will read based on jumper settings (connected to 1 or 0)..

is this possible ? if yes, wont it be a problem to leave the 2 FPGA address pins floating & also will adding jumpers in address lines cause any SI issues?

if anyone has some other options to load different config files based on external control, please do suggest ....