Question for ArduCopter configuration for pixhawk

Hi, I have a strange question.
But, I need it for some reason.

I have a pixhawk which consists of two processor, cortex-M4 and cortex-M3.
However, if I want to operate pixhawk with only cortex-M4, is there a some configuration for it? (or original firmware still works even if cortex-M3 died)

If it is possible, could you tell me some potential problem with one processor?
e.g., cortex-M3 is responsible for fail-safe function , So it won’t land safely if some exception case such as low battery.

Thank you

I might be wrong but I think only the main processor is used on a Pixhawk to run Arducopter (or Arduplane). The other one is just for providing a direct manual PWM control of your ship in case of failure of the main one, which never happened anyway as far as I know.