Your idea makes sense. We tried to implement a new patch according to your idea, it could fix our booting hang problem. We will push patch for review soon. BTW, it is better to have " uart_is_nbcon " checking in nbcon_release as well as it in nbcon_acquire. 😊 Two patches will be pushed together for review. > We could move the @locked_port flag to the struct uart_port. (Probably renaming it to @nbcon_locked_port.) I think that would be the appropriate fix. > John
