enum xenbus_state xenbus_read_driver_state(const char *path);
+__attribute__((format(printf, 3, 4)))
void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...);
+__attribute__((format(printf, 3, 4)))
void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...);
const char *xenbus_strstate(enum xenbus_state state);