getboottime64(9)

💖 NAME 💖

okay so bestie, welcome to getboottime64(9) from the Kernel API Manual — this is the page for getboottime64, which returns the real time of system boot. that's it, that's the name, and honestly it ate. 💅

✨ SYNOPSIS ✨

the signature is lowkey tiny, but here it is exactly:

void getboottime64 (struct timespec64 *ts );

🧚 ARGUMENTS 🧚

• ts — pointer to the timespec64 to be set. yep, that's the whole argument list; it's giving minimalism. 🎀

🦋 DESCRIPTION 🦋

okay so what's the tea? it returns the wall-time of boot in a timespec64. 🕰️

this is based on the wall_to_monotonic offset and the total suspend time. no cap.

and listen: calls to settimeofday will affect the value returned — which basically means that however wrong your real time clock is at boot time, you get the right time here. iconic behavior, honestly. 😭

🌈 SEE ALSO 🌈

the whole timekeeping friend group is here, go say hi:

• Kernel file ./kernel/time/timekeeping.c
• struct tk_fast(9)
• tk_setup_internals(9)
• update_fast_timekeeper(9)
• ktime_get_mono_fast_ns(9)
• ktime_get_raw_fast_ns(9)
• ktime_get_boot_fast_ns(9)
• ktime_get_tai_fast_ns(9)
• ktime_get_real_fast_ns(9)
• halt_fast_timekeeper(9)
• pvclock_gtod_register_notifier(9)
• pvclock_gtod_unregister_notifier(9)
• timekeeping_forward_now(9)
• ktime_get_real_ts64(9)
• ktime_mono_to_any(9)
• ktime_get_raw(9)
• ktime_get_ts64(9)
• ktime_get_seconds(9)
• ktime_get_real_seconds(9)
• __ktime_get_real_seconds(9)
• ktime_get_snapshot_id(9)
• adjust_historical_crosststamp(9)
• ktime_real_to_base_clock(9)
• get_device_system_crosststamp(9)
• timekeeping_clocksource_has_base(9)
• do_settimeofday64(9)
• __timekeeping_inject_offset(9)
• timekeeping_notify(9)
• ktime_get_raw_ts64(9)
• timekeeping_valid_for_hres(9)
• timekeeping_max_deferment(9)
• read_persistent_clock64(9)
• read_persistent_wall_and_boot_offset(9)
• __timekeeping_inject_sleeptime(9)
• timekeeping_inject_sleeptime64(9)
• timekeeping_resume(9)
• update_wall_time(9)
• ktime_get_coarse_real_ts64_mg(9)
• ktime_get_real_ts64_mg(9)
• ktime_get_update_offsets_now(9)
• random_get_entropy_fallback(9)
• do_adjtimex(9)
• hardpps(9)
• ktime_get_aux(9)
• ktime_get_aux_ts64(9)

sign-off bestie: this page's source/version is ./kernel/time, dated October 2026, and it's the getboottime64(9) manual. mwah, byeeee 🫶💖