HW TIMESTAMPING(9)

💅 HW TIMESTAMPING 💅

okay so this one is straight out of the Kernel API Manual, section 9 — HW timestamping, aka the page that explains how your driver tells mac80211 exactly when a thing happened. Iconic behaviour honestly, because timing is literally the whole point. ⏱️✨

🎀 DESCRIPTION 🎀

Timing Measurement and Fine Timing Measurement require accurate timestamps of the action frames TX/RX and their respective acks. That's the vibe check the whole page is built on — no accurate timestamp, no FTM, periodt. 💀

To report hardware timestamps for Timing Measurement or Fine Timing Measurement frame RX, the low level driver should set the SKB's hwtstamp field to the frame RX timestamp and report the ack TX timestamp in the ieee80211_rx_status struct.

Similarly, to report hardware timestamps for Timing Measurement or Fine Timing Measurement frame TX, the driver should set the SKB's hwtstamp field to the frame TX timestamp and report the ack RX timestamp in the ieee80211_tx_status struct.

bestie pls notice how it flips 🙈 — RX on the frame means the ack timestamp goes in ieee80211_rx_status, and TX on the frame means the ack timestamp goes in ieee80211_tx_status. Yes, they mirror each other. Yes, it's giving symmetry. 💅

🌈 SEE ALSO 🌈

okay so this list is lowkey a whole syllabus 😭 but i promised not to skip a single one, so here's every single reference, in the exact order it appears, no cap:

• Kernel file ./include/net/mac80211.h, Introduction(9), Calling mac80211 from interrupts(9), Warning(9), Frame format(9), mac80211 workqueue(9), mac80211 software tx queueing(9)
• enum ieee80211_max_queues(9), enum ieee80211_ac_numbers(9), struct ieee80211_tx_queue_params(9), enum ieee80211_chanctx_change(9), struct ieee80211_chan_req(9), struct ieee80211_chanctx_conf(9), enum ieee80211_chanctx_switch_mode(9), struct ieee80211_vif_chanctx_switch(9)
• enum ieee80211_bss_change(9), enum ieee80211_event_type(9), enum ieee80211_rssi_event_data(9), struct ieee80211_rssi_event(9), enum ieee80211_mlme_event_data(9), enum ieee80211_mlme_event_status(9), struct ieee80211_mlme_event(9), struct ieee80211_ba_event(9), struct ieee80211_event(9)
• struct ieee80211_mu_group_data(9), struct ieee80211_ftm_responder_params(9), struct ieee80211_fils_discovery(9), struct ieee80211_parsed_tpe(9), struct ieee80211_bss_npca_params(9), struct ieee80211_bss_conf(9), struct ieee80211_nan_channel(9), struct ieee80211_nan_peer_map(9), struct ieee80211_nan_peer_sched(9)
• enum mac80211_tx_info_flags(9), enum mac80211_tx_control_flags(9), enum mac80211_tx_status_flags(9), enum mac80211_rate_control_flags(9), struct ieee80211_tx_rate(9), struct ieee80211_tx_info(9), struct ieee80211_tx_status(9), struct ieee80211_scan_ies(9), ieee80211_tx_info_clear_status(9)
• enum mac80211_rx_flags(9), enum mac80211_rx_encoding_flags(9), struct ieee80211_rx_status(9), enum ieee80211_conf_flags(9), enum ieee80211_conf_changed(9), enum ieee80211_smps_mode(9), struct ieee80211_conf(9), struct ieee80211_channel_switch(9)
• enum ieee80211_vif_flags(9), enum ieee80211_offload_flags(9), struct ieee80211_eml_params(9), struct ieee80211_nan_sched_cfg(9), struct ieee80211_vif_cfg(9), struct ieee80211_neg_ttlm(9), enum ieee80211_neg_ttlm_res(9), struct ieee80211_vif(9), ieee80211_vif_usable_links(9), ieee80211_vif_is_mld(9), ieee80211_vif_link_active(9), wdev_to_ieee80211_vif(9), ieee80211_vif_to_wdev(9)
• enum ieee80211_key_flags(9), struct ieee80211_key_conf(9), struct ieee80211_key_seq(9), enum set_key_cmd(9), enum ieee80211_sta_state(9), enum ieee80211_sta_rx_bandwidth(9), struct ieee80211_sta_rates(9), struct ieee80211_sta_txpwr(9), struct ieee80211_sta_aggregates(9), struct ieee80211_link_sta(9), struct ieee80211_sta(9), enum sta_notify_cmd(9), struct ieee80211_tx_control(9), struct ieee80211_txq(9)
• enum ieee80211_hw_flags(9), struct ieee80211_hw(9), struct ieee80211_scan_request(9), struct ieee80211_tdls_ch_sw_params(9), wiphy_to_ieee80211_hw(9), SET_IEEE80211_DEV(9), SET_IEEE80211_PERM_ADDR(9), ieee80211_free_txskb(9), ieee80211_purge_tx_queue(9)
• Hardware crypto acceleration(9), Powersave support(9), Beacon filter support(9), Spatial multiplexing power save(9), Frame filtering(9), AP support for powersaving clients(9), HW queue control(9)
• enum ieee80211_filter_flags(9), enum ieee80211_ampdu_mlme_action(9), struct ieee80211_ampdu_params(9), enum ieee80211_frame_release_type(9), enum ieee80211_rate_control_changed(9), enum ieee80211_roc_type(9), enum ieee80211_reconfig_type(9), struct ieee80211_prep_tx_info(9), struct ieee80211_ops(9)
• ieee80211_alloc_hw_nm(9), ieee80211_alloc_hw(9), ieee80211_register_hw(9), struct ieee80211_tpt_blink(9), enum ieee80211_tpt_led_trigger_flags(9), ieee80211_get_tx_led_name(9), ieee80211_get_rx_led_name(9), ieee80211_get_assoc_led_name(9), ieee80211_get_radio_led_name(9), ieee80211_create_tpt_led_trigger(9), ieee80211_unregister_hw(9), ieee80211_free_hw(9), ieee80211_restart_hw(9)
• ieee80211_rx_list(9), ieee80211_rx_napi(9), ieee80211_rx(9), ieee80211_rx_irqsafe(9), ieee80211_rx_ni(9), ieee80211_sta_ps_transition(9), ieee80211_sta_ps_transition_ni(9), ieee80211_sta_pspoll(9), ieee80211_sta_uapsd_trigger(9), ieee80211_sta_set_buffered(9), ieee80211_get_tx_rates(9), ieee80211_tx_rate_update(9), ieee80211_tx_status_skb(9), ieee80211_tx_status_ext(9), ieee80211_tx_status_noskb(9), ieee80211_tx_status_ni(9), ieee80211_tx_status_irqsafe(9), ieee80211_report_low_ack(9)
• struct ieee80211_mutable_offsets(9), ieee80211_beacon_get_template(9), ieee80211_beacon_get_template_ema_index(9), struct ieee80211_ema_beacons(9), ieee80211_beacon_get_template_ema_list(9), ieee80211_beacon_free_ema_list(9), ieee80211_beacon_get_tim(9), ieee80211_beacon_get(9), ieee80211_beacon_update_cntdwn(9), ieee80211_beacon_set_cntdwn(9), ieee80211_csa_finish(9), ieee80211_beacon_cntdwn_is_complete(9), ieee80211_color_change_finish(9), ieee80211_proberesp_get(9), ieee80211_pspoll_get(9), ieee80211_nullfunc_get(9), ieee80211_probereq_get(9), ieee80211_rts_get(9), ieee80211_rts_duration(9), ieee80211_ctstoself_get(9), ieee80211_ctstoself_duration(9), ieee80211_generic_frame_duration(9), ieee80211_get_buffered_bc(9)
• ieee80211_get_tkip_p1k_iv(9), ieee80211_get_tkip_p1k(9), ieee80211_get_tkip_rx_p1k(9), ieee80211_get_tkip_p2k(9), ieee80211_tkip_add_iv(9), ieee80211_get_key_rx_seq(9), ieee80211_set_key_rx_seq(9), ieee80211_gtk_rekey_add(9), ieee80211_gtk_rekey_notify(9), ieee80211_key_mic_failure(9), ieee80211_key_replay(9)
• ieee80211_wake_queue(9), ieee80211_stop_queue(9), ieee80211_queue_stopped(9), ieee80211_stop_queues(9), ieee80211_wake_queues(9), ieee80211_scan_completed(9), ieee80211_sched_scan_results(9), ieee80211_sched_scan_stopped(9)
• enum ieee80211_interface_iteration_flags(9), ieee80211_iterate_interfaces(9), ieee80211_iterate_active_interfaces(9), ieee80211_iterate_active_interfaces_atomic(9), for_each_interface(9), for_each_active_interface(9), ieee80211_iterate_active_interfaces_mtx(9), ieee80211_iterate_stations_atomic(9), for_each_station(9), ieee80211_iterate_stations_mtx(9)
• ieee80211_queue_work(9), ieee80211_queue_delayed_work(9), ieee80211_refresh_tx_agg_session_timer(9), ieee80211_start_tx_ba_session(9), ieee80211_start_tx_ba_cb_irqsafe(9), ieee80211_stop_tx_ba_session(9), ieee80211_stop_tx_ba_cb_irqsafe(9)
• ieee80211_find_sta(9), ieee80211_find_sta_by_ifaddr(9), ieee80211_find_sta_by_link_addrs(9), ieee80211_sta_block_awake(9), ieee80211_sta_eosp(9), ieee80211_send_eosp_nullfunc(9), ieee80211_sta_recalc_aggregates(9), ieee80211_sta_register_airtime(9), ieee80211_txq_airtime_check(9), ieee80211_txq_aql_pending(9), ieee80211_iter_keys(9), ieee80211_iter_keys_rcu(9), ieee80211_iter_chan_contexts_atomic(9), ieee80211_iter_chan_contexts_mtx(9), ieee80211_ap_probereq_get(9)
• ieee80211_beacon_loss(9), ieee80211_connection_loss(9), ieee80211_disconnect(9), ieee80211_resume_disconnect(9), ieee80211_hw_restart_disconnect(9), ieee80211_cqm_rssi_notify(9), ieee80211_cqm_beacon_loss_notify(9), ieee80211_radar_detected(9), ieee80211_chswitch_done(9), ieee80211_channel_switch_disconnect(9), ieee80211_request_smps(9), ieee80211_ready_on_channel(9), ieee80211_remain_on_channel_expired(9), ieee80211_stop_rx_ba_session(9), ieee80211_mark_rx_ba_filtered_frames(9), ieee80211_send_bar(9), ieee80211_manage_rx_ba_offl(9), ieee80211_start_rx_ba_session_offl(9), ieee80211_stop_rx_ba_session_offl(9), ieee80211_rx_ba_timer_expired(9)
• struct ieee80211_tx_rate_control(9), enum rate_control_capabilities(9), rate_control_set_rates(9), ieee80211_get_he_iftype_cap_vif(9), ieee80211_get_he_6ghz_capa_vif(9), ieee80211_get_eht_iftype_cap_vif(9), ieee80211_get_uhr_iftype_cap_vif(9), ieee80211_update_mu_groups(9), ieee80211_ave_rssi(9), ieee80211_calculate_rx_timestamp(9), ieee80211_report_wowlan_wakeup(9), ieee80211_tx_prepare_skb(9), ieee80211_parse_tx_radiotap(9)
• struct ieee80211_noa_data(9), ieee80211_parse_p2p_noa(9), ieee80211_update_p2p_noa(9), ieee80211_tdls_oper_request(9), ieee80211_reserve_tid(9), ieee80211_unreserve_tid(9), ieee80211_tx_dequeue(9), ieee80211_tx_dequeue_ni(9), ieee80211_handle_wake_tx_queue(9), ieee80211_next_txq(9), ieee80211_txq_schedule_start(9), ieee80211_schedule_txq(9), ieee80211_return_txq(9), ieee80211_txq_may_transmit(9), ieee80211_txq_get_depth(9)
• ieee80211_nan_func_terminated(9), ieee80211_nan_func_match(9), ieee80211_nan_sched_update_done(9), ieee80211_nan_cluster_joined(9), ieee80211_nan_try_evacuate(9), ieee80211_calc_rx_airtime(9), ieee80211_calc_tx_airtime(9), ieee80211_get_fils_discovery_tmpl(9), ieee80211_get_unsol_bcast_probe_resp_tmpl(9), ieee80211_obss_color_collision_notify(9), ieee80211_is_tx_data(9), ieee80211_set_active_links(9), ieee80211_set_active_links_async(9), ieee80211_send_teardown_neg_ttlm(9), ieee80211_chan_width_to_rx_bw(9), ieee80211_prepare_rx_omi_bw(9), ieee80211_finalize_rx_omi_bw(9), ieee80211_vif_nan_started(9), ieee80211_encrypt_tx_skb(9)

and that's the whole page bestie 🫶 source is ./include/net, dated October 2026, and it's filed under HW timestamping(9) in the Kernel API Manual — go set that hwtstamp field and slay 💖🦋⭐