POWERSAVE SUPPORT(9)

📦 version 7.3.1, in nixpkgs unstable

💤 Powersave support 💤

Powersave support(9) — Kernel API Manual

Okay so bestie, welcome to the powersave lore: mac80211 has support for various powersave implementations. Slay.

First up, it can support hardware that handles all the powersaving by itself. That kind of hardware should simply set the IEEE80211_HW_SUPPORTS_PS hardware flag. In that case, it will be told about the desired powersave mode with the IEEE80211_CONF_PS flag depending on the association status. The hardware must take care of sending nullfunc frames when necessary — i.e. when entering and leaving powersave mode. And it is required to look at the AID in beacons and signal to the AP that it woke up when it finds traffic directed to it. Main character hardware energy, honestly. 👑

IEEE80211_CONF_PS flag enabled means that the powersave mode defined in IEEE 802.11-2007 section 11.2 is enabled. Do not confuse this with hardware wakeup and sleep states, okay? That's a different vibe entirely. Driver is responsible for waking up the hardware before issuing commands to the hardware and putting it back to sleep at appropriate times. Periodt.

When PS is enabled, hardware needs to wakeup for beacons and receive the buffered multicast/broadcast frames after the beacon. Also it must be possible to send frames and receive the acknowledment frame. Yep, exactly like that. 😭

Other hardware designs cannot send nullfunc frames by themselves and also need software support for parsing the TIM bitmap. This is also supported by mac80211 by combining the IEEE80211_HW_SUPPORTS_PS and IEEE80211_HW_PS_NULLFUNC_STACK flags. The hardware is of course still required to pass up beacons. It is still required to handle waking up for multicast traffic; if it cannot, the driver must handle that as best as it can; mac80211 is too slow to do that. Fr fr, too slow. 💀

Dynamic powersave is an extension to normal powersave in which the hardware stays awake for a user-specified period of time after sending a frame so that reply frames need not be buffered and therefore delayed to the next wakeup. It's a compromise of getting good enough latency when there's data traffic and still saving significantly power in idle periods. Lowkey a trade-off, highkey iconic.

Dynamic powersave is simply supported by mac80211 enabling and disabling PS based on traffic. Driver needs to only set the IEEE80211_HW_SUPPORTS_PS flag and mac80211 will handle everything automatically. Additionally, hardware having support for the dynamic PS feature may set the IEEE80211_HW_SUPPORTS_DYNAMIC_PS flag to indicate that it can support dynamic PS mode itself. The driver needs to look at the dynamic_ps_timeout hardware configuration value and use it that value whenever IEEE80211_CONF_PS is set. In this case mac80211 will disable dynamic PS feature in stack and will just keep IEEE80211_CONF_PS enabled whenever user has enabled powersave. Got it? Got it. 💅

Driver informs U-APSD client support by enabling the IEEE80211_VIF_SUPPORTS_UAPSD flag. The mode is configured through the uapsd parameter in conf_tx operation. Hardware needs to send the QoS Nullfunc frames and stay awake until the service period has ended. To utilize U-APSD, dynamic powersave is disabled for voip AC and all frames from that AC are transmitted with powersave enabled. That's the U-APSD client tea. 🫖

Note: U-APSD client mode is not yet supported with IEEE80211_HW_PS_NULLFUNC_STACK. Big important caveat, bestie — not yet. 🚨

👀 SEE ALSO ✨

okay bestie, this is the part where the page just. lists. everything. no cap, it's a lot — but you're gonna want these bookmarked, so let's go 💖

The whole family lives in the kernel file ./include/net/mac80211.h — that's the mothership, that's the source of truth, that's the group chat admin.

🌱 start here, bestie

  • 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)
  • HW timestamping(9)

📬 queues & channel contexts

  • 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)

🎀 events, BSS config & NAN structs

  • 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)

📡 tx/rx info & status

  • 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)

🦋 conf & vif

🔑 keys

  • enum ieee80211_key_flags(9)
  • struct ieee80211_key_conf(9)
  • struct ieee80211_key_seq(9)
  • enum set_key_cmd(9)

👑 sta, hw & the little helpers

💅 the big capability pages

these are the iconique ones, honestly:

  • Hardware crypto acceleration(9)
  • Beacon filter support(9)
  • Spatial multiplexing power save(9)
  • Frame filtering(9)
  • AP support for powersaving clients(9)
  • HW queue control(9)

🧚 ops & the fun enums

  • 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)

🌸 alloc / register / leds / restart / rx

⭐ tx status crew

🎀 beacons

🍓 frame templates

🔥 tkip & key stuff

💜 queue wake/stop + scan

🌈 iterators + work queueing

✨ tx aggregation + airtime

🫶 iter keys / chan contexts

💖 notifications & loss events

🧚 rx ba offload

🌸 rate control & caps & misc

🦋 txq scheduling

🎀 nan + airtime calc

👑 the last batch, we made it

okay that's the whole list, no skips, no "etc." — every single one is up there 💀 if a friend asks "where do I even start", point them at Introduction(9) and let them cook.

and that's a wrap on this page, bestie 🫶 the source is ./include/net, dated October 2026, and the page itself is Powersave support(9) — screenshot the footer, tag me, whatever, it's iconic 💅✨

📦 where this page comes from