time_travel_start
err = kstrtoull(str, 0, &time_travel_start);
static unsigned long long time_travel_start;
time_travel_start = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
time_travel_start -= time_travel_time;
time_travel_start = os_persistent_clock_emulation();
nsecs = time_travel_start + time_travel_time;