void prom_vprintf (char *fmt, va_list ap) __attribute__ ((format (printf, 1, 0)));
void prom_fprintf (prom_handle dev, char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
void prom_printf (char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
void prom_vprintf (char *fmt, va_list ap) __attribute__ ((format (printf, 1, 0)));
void prom_fprintf (prom_handle dev, char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
void prom_printf (char *fmt, ...) __attribute__ ((format (printf, 1, 2)));