static void virtser_port_device_realize(DeviceState *dev, Error **errp)
{
    VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
    VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
    VirtIOSerialBus *bus = VIRTIO_SERIAL_BUS(qdev_get_parent_bus(dev));
    int max_nr_ports;
    bool plugging_port0;
    Error *err = NULL;

    port->vser = bus->vser;
    port->bh = qemu_bh_new(flush_queued_data_bh, port);

    assert(vsc->have_data);

    /*
     * Is the first console port we're seeing? If so, put it up at
     * location 0. This is done for backward compatibility (old
     * kernel, new qemu).
     */
    plugging_port0 = vsc->is_console && !find_port_by_id(port->vser, 0);

    if (find_port_by_id(port->vser, port->id)) {
        error_setg(errp, "virtio-serial-bus: A port already exists at id %u",
                   port->id);
        return;
    }

    if (port->name != NULL && find_port_by_name(port->name)) {
        error_setg(errp, "virtio-serial-bus: A port already exists by name %s",
                   port->name);
        return;
    }

    if (port->id == VIRTIO_CONSOLE_BAD_ID) {
        if (plugging_port0) {
            port->id = 0;
        } else {
            port->id = find_free_port_id(port->vser);
            if (port->id == VIRTIO_CONSOLE_BAD_ID) {
                error_setg(errp, "virtio-serial-bus: Maximum port limit for "
                                 "this device reached");
                return;
            }
        }
    }

    max_nr_ports = port->vser->serial.max_virtserial_ports;
    if (port->id >= max_nr_ports) {
        error_setg(errp, "virtio-serial-bus: Out-of-range port id specified, "
                         "max. allowed: %u", max_nr_ports - 1);
        return;
    }

    vsc->realize(dev, &err);
    if (err != NULL) {
        error_propagate(errp, err);
        return;
    }

    port->elem.out_num = 0;
}