Restart Script to Select OS

Is it possible to make a script that restart my Dual Boot machine into a specific OS? Currently running Kubuntu 19.10 and Windows XP. I'd like to be able to select my default boot OS before restarting. I did some googling and found that efibootmgr might be able to do this but after installing it I received the following message...
Code:EFI variables are not supported on this system.