[LinuxBIOS] Please explain why is some hardware not supported even though it runs fine in linux

[Michal Pomorski]

Take for instance nForce2 chipset and please correct me if i am wrong.
Linux have full hardware support for it right ? (it should since i use one)
Linux doesnt use bios functions because it controlls all the hardware on 
the motherboard right?
So if there is a way for linux to controll the hardware why is it 
impossible to implement it in a free bios?

What is so special about linux bios that needs special vendor support 
that linux os doesnt?