8042 Controller emulation unsupported functions?

[superfury]

I'm making an x86 emulator (currently up to 80186). I'm currently working on the 8042 Controller (keyboard only). Is it OK to give an 0xFE error (unsupported command) when receiving commands 0xF7-0xFD? Or does this absolutely have to be emulated? (Blocking mode 3 operations atm.)