How does pixhawk takes motor parameters

I want to know how does pixhawk understands the motor configuration parameters like KV, Transfer function etc. My understanding is, to design an auto flight mode motor transfer function is required. but pixhawk does not ask user to provide motor configuration parameters.
Is pixhawk passing any impulse signal to calculate motor configuration parameter or it is not required to design a controller ?

attitude controllers are PIDs, with default values for common airframes. If your copter didn’t behave well, you have to tune PIDs manualy.

I agree to fact that pid has to be tuned in case airframe changes. But I want to know about motor parameters. In case I change motor how will pixhawk configure itself for the new motor?

You may have to re-tune the PIDs and also adapt the mid Throttle Speed for hovering as well as min throttle Speed (idle).