FRAME FORMAT(9)

💅 Frame format — Kernel API Manual, section 9 🎀

okay bestie, sit down, because this is the frame format(9) page and it's short but it's important, like the little note your bff slips you before the exam. pop it in your brain and keep it there 🧠✨

🦋 the actual rule (the general one, no cap)

as a general rule, when frames are passed between mac80211 and the driver, they start with the IEEE 802.11 header and include the same octets that are sent over the air — except for the FCS, which should be calculated by the hardware. so like… the FCS is not your problem, the hardware is handling that, periodt 💅

🌸 but wait — the exceptions (advanced features only, iykyk)

there are, however, various exceptions to this rule for advanced features:

• the first exception — it's for hardware encryption and decryption offload, where the IV/ICV may or may not be generated in hardware. so yeah, may or may not, those are genuinely both on the table 🙈
• secondly — when the hardware handles fragmentation, the frame handed to the driver from mac80211 is the MSDU, not the MPDU. lowkey the most important sentence here, like don't mix those up bestie, MSDU ≠ MPDU, fr fr 😭

✨ SEE ALSO ✨

so here's the thing — this list is long. like, scroll-for-a-while long. but every single one of these is a real page and they're all your new besties, so I'm listing every last one because we do not skip references in this house 👑💖

• Kernel file ./include/net/mac80211.h
• Introduction(9)
• Calling mac80211 from interrupts(9)
• Warning(9)
• mac80211 workqueue(9)
• mac80211 software tx queueing(9)
• HW timestamping(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, you ate that 🫶✨ go forth and pass frames correctly, and remember: header first, FCS is the hardware's business, and MSDU-not-MPDU when fragmentation is offloaded. iconic behaviour only 💅💖

this page came from ./include/net in the Kernel API Manual, dated October 2026, and its title is Frame format(9) — so if you cite it in your essay, that's the flex 🌈⭐🎀