void pevent_register_trace_clock(struct pevent *pevent, char *trace_clock);
int pevent_register_function(struct pevent *pevent, char *name,
unsigned long long addr, char *mod);
-int pevent_register_print_string(struct pevent *pevent, char *fmt,
+int pevent_register_print_string(struct pevent *pevent, const char *fmt,
unsigned long long addr);
int pevent_pid_is_registered(struct pevent *pevent, int pid);