void sn_transmit_chars (struct sn_cons_port * port, int raw);
If we're early, before we're registered with serial core, the writes are going through sn_sal_console_write because that's how register_console has been set up. We currently could have asynch polls calling this function due to sn_sal_switch_to_asynch but we can ignore them until we register with the serial core stuffs.