static void virtser_bus_class_init(ObjectClass *klass, void *data)
{
    BusClass *k = BUS_CLASS(klass);
    k->print_dev = virtser_bus_dev_print;
}
static void virtser_bus_class_init(ObjectClass *klass, void *data)
{
    BusClass *k = BUS_CLASS(klass);
    k->print_dev = virtser_bus_dev_print;
}