Hi Felipe, I think I know why my application is not receiving SIGHUP. When HOST sends SET_CONFIGURATION the set_config() in composite.c calls acm_set_alt(). Now acm_set_alt() calls gserial_connect() and it will create new port. But it never called gserial_disconnect() to close previously called gserial_connect(), so SIGHUP is not generated. But why acm_set_alt() does not do gserial_disconnect() before calling gserial_connect()? Regards, Dipen Patel -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html