The 802.11 subsystems – for kernel developers
Explaining wireless 802.11 networking in the Linux kernel
2007-2009
Johannes Berg
Johannes
Berg
johannes@sipsolutions.net
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License version 2 as published by the Free Software Foundation.
This documentation is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this documentation; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
For more details see the file COPYING in the source
distribution of Linux.
These books attempt to give a description of the
various subsystems that play a role in 802.11 wireless
networking in Linux. Since these books are for kernel
developers they attempts to document the structures
and functions used in the kernel as well as giving a
higher-level overview.
The reader is expected to be familiar with the 802.11
standard as published by the IEEE in 802.11-2007 (or
possibly later versions). References to this standard
will be given as "802.11-2007 8.1.5".
The cfg80211 subsystem
!Pinclude/net/cfg80211.h Introduction
Device registration
!Pinclude/net/cfg80211.h Device registration
!Finclude/net/cfg80211.h ieee80211_band
!Finclude/net/cfg80211.h ieee80211_channel_flags
!Finclude/net/cfg80211.h ieee80211_channel
!Finclude/net/cfg80211.h ieee80211_rate_flags
!Finclude/net/cfg80211.h ieee80211_rate
!Finclude/net/cfg80211.h ieee80211_sta_ht_cap
!Finclude/net/cfg80211.h ieee80211_supported_band
!Finclude/net/cfg80211.h cfg80211_signal_type
!Finclude/net/cfg80211.h wiphy_params_flags
!Finclude/net/cfg80211.h wiphy_flags
!Finclude/net/cfg80211.h wiphy
!Finclude/net/cfg80211.h wireless_dev
!Finclude/net/cfg80211.h wiphy_new
!Finclude/net/cfg80211.h wiphy_register
!Finclude/net/cfg80211.h wiphy_unregister
!Finclude/net/cfg80211.h wiphy_free
!Finclude/net/cfg80211.h wiphy_name
!Finclude/net/cfg80211.h wiphy_dev
!Finclude/net/cfg80211.h wiphy_priv
!Finclude/net/cfg80211.h priv_to_wiphy
!Finclude/net/cfg80211.h set_wiphy_dev
!Finclude/net/cfg80211.h wdev_priv
Actions and configuration
!Pinclude/net/cfg80211.h Actions and configuration
!Finclude/net/cfg80211.h cfg80211_ops
!Finclude/net/cfg80211.h vif_params
!Finclude/net/cfg80211.h key_params
!Finclude/net/cfg80211.h survey_info_flags
!Finclude/net/cfg80211.h survey_info
!Finclude/net/cfg80211.h beacon_parameters
!Finclude/net/cfg80211.h plink_actions
!Finclude/net/cfg80211.h station_parameters
!Finclude/net/cfg80211.h station_info_flags
!Finclude/net/cfg80211.h rate_info_flags
!Finclude/net/cfg80211.h rate_info
!Finclude/net/cfg80211.h station_info
!Finclude/net/cfg80211.h monitor_flags
!Finclude/net/cfg80211.h mpath_info_flags
!Finclude/net/cfg80211.h mpath_info
!Finclude/net/cfg80211.h bss_parameters
!Finclude/net/cfg80211.h ieee80211_txq_params
!Finclude/net/cfg80211.h cfg80211_crypto_settings
!Finclude/net/cfg80211.h cfg80211_auth_request
!Finclude/net/cfg80211.h cfg80211_assoc_request
!Finclude/net/cfg80211.h cfg80211_deauth_request
!Finclude/net/cfg80211.h cfg80211_disassoc_request
!Finclude/net/cfg80211.h cfg80211_ibss_params
!Finclude/net/cfg80211.h cfg80211_connect_params
!Finclude/net/cfg80211.h cfg80211_pmksa
!Finclude/net/cfg80211.h cfg80211_send_rx_auth
!Finclude/net/cfg80211.h cfg80211_send_auth_timeout
!Finclude/net/cfg80211.h __cfg80211_auth_canceled
!Finclude/net/cfg80211.h cfg80211_send_rx_assoc
!Finclude/net/cfg80211.h cfg80211_send_assoc_timeout
!Finclude/net/cfg80211.h cfg80211_send_deauth
!Finclude/net/cfg80211.h __cfg80211_send_deauth
!Finclude/net/cfg80211.h cfg80211_send_disassoc
!Finclude/net/cfg80211.h __cfg80211_send_disassoc
!Finclude/net/cfg80211.h cfg80211_ibss_joined
!Finclude/net/cfg80211.h cfg80211_connect_result
!Finclude/net/cfg80211.h cfg80211_roamed
!Finclude/net/cfg80211.h cfg80211_disconnected
!Finclude/net/cfg80211.h cfg80211_ready_on_channel
!Finclude/net/cfg80211.h cfg80211_remain_on_channel_expired
!Finclude/net/cfg80211.h cfg80211_new_sta
!Finclude/net/cfg80211.h cfg80211_rx_mgmt
!Finclude/net/cfg80211.h cfg80211_mgmt_tx_status
!Finclude/net/cfg80211.h cfg80211_cqm_rssi_notify
!Finclude/net/cfg80211.h cfg80211_cqm_pktloss_notify
!Finclude/net/cfg80211.h cfg80211_michael_mic_failure
Scanning and BSS list handling
!Pinclude/net/cfg80211.h Scanning and BSS list handling
!Finclude/net/cfg80211.h cfg80211_ssid
!Finclude/net/cfg80211.h cfg80211_scan_request
!Finclude/net/cfg80211.h cfg80211_scan_done
!Finclude/net/cfg80211.h cfg80211_bss
!Finclude/net/cfg80211.h cfg80211_inform_bss_frame
!Finclude/net/cfg80211.h cfg80211_inform_bss
!Finclude/net/cfg80211.h cfg80211_unlink_bss
!Finclude/net/cfg80211.h cfg80211_find_ie
!Finclude/net/cfg80211.h ieee80211_bss_get_ie
Utility functions
!Pinclude/net/cfg80211.h Utility functions
!Finclude/net/cfg80211.h ieee80211_channel_to_frequency
!Finclude/net/cfg80211.h ieee80211_frequency_to_channel
!Finclude/net/cfg80211.h ieee80211_get_channel
!Finclude/net/cfg80211.h ieee80211_get_response_rate
!Finclude/net/cfg80211.h ieee80211_hdrlen
!Finclude/net/cfg80211.h ieee80211_get_hdrlen_from_skb
!Finclude/net/cfg80211.h ieee80211_radiotap_iterator
Data path helpers
!Pinclude/net/cfg80211.h Data path helpers
!Finclude/net/cfg80211.h ieee80211_data_to_8023
!Finclude/net/cfg80211.h ieee80211_data_from_8023
!Finclude/net/cfg80211.h ieee80211_amsdu_to_8023s
!Finclude/net/cfg80211.h cfg80211_classify8021d
Regulatory enforcement infrastructure
!Pinclude/net/cfg80211.h Regulatory enforcement infrastructure
!Finclude/net/cfg80211.h regulatory_hint
!Finclude/net/cfg80211.h wiphy_apply_custom_regulatory
!Finclude/net/cfg80211.h freq_reg_info
RFkill integration
!Pinclude/net/cfg80211.h RFkill integration
!Finclude/net/cfg80211.h wiphy_rfkill_set_hw_state
!Finclude/net/cfg80211.h wiphy_rfkill_start_polling
!Finclude/net/cfg80211.h wiphy_rfkill_stop_polling
Test mode
!Pinclude/net/cfg80211.h Test mode
!Finclude/net/cfg80211.h cfg80211_testmode_alloc_reply_skb
!Finclude/net/cfg80211.h cfg80211_testmode_reply
!Finclude/net/cfg80211.h cfg80211_testmode_alloc_event_skb
!Finclude/net/cfg80211.h cfg80211_testmode_event
The mac80211 subsystem
!Pinclude/net/mac80211.h Introduction
!Pinclude/net/mac80211.h Warning
The basic mac80211 driver interface
You should read and understand the information contained
within this part of the book while implementing a driver.
In some chapters, advanced usage is noted, that may be
skipped at first.
This part of the book only covers station and monitor mode
functionality, additional information required to implement
the other modes is covered in the second part of the book.
Basic hardware handling
TBD
This chapter shall contain information on getting a hw
struct allocated and registered with mac80211.
Since it is required to allocate rates/modes before registering
a hw struct, this chapter shall also contain information on setting
up the rate/mode structs.
Additionally, some discussion about the callbacks and
the general programming model should be in here, including
the definition of ieee80211_ops which will be referred to
a lot.
Finally, a discussion of hardware capabilities should be done
with references to other parts of the book.
!Finclude/net/mac80211.h ieee80211_hw
!Finclude/net/mac80211.h ieee80211_hw_flags
!Finclude/net/mac80211.h SET_IEEE80211_DEV
!Finclude/net/mac80211.h SET_IEEE80211_PERM_ADDR
!Finclude/net/mac80211.h ieee80211_ops
!Finclude/net/mac80211.h ieee80211_alloc_hw
!Finclude/net/mac80211.h ieee80211_register_hw
!Finclude/net/mac80211.h ieee80211_get_tx_led_name
!Finclude/net/mac80211.h ieee80211_get_rx_led_name
!Finclude/net/mac80211.h ieee80211_get_assoc_led_name
!Finclude/net/mac80211.h ieee80211_get_radio_led_name
!Finclude/net/mac80211.h ieee80211_unregister_hw
!Finclude/net/mac80211.h ieee80211_free_hw
PHY configuration
TBD
This chapter should describe PHY handling including
start/stop callbacks and the various structures used.
!Finclude/net/mac80211.h ieee80211_conf
!Finclude/net/mac80211.h ieee80211_conf_flags
Virtual interfaces
TBD
This chapter should describe virtual interface basics
that are relevant to the driver (VLANs, MGMT etc are not.)
It should explain the use of the add_iface/remove_iface
callbacks as well as the interface configuration callbacks.
Things related to AP mode should be discussed there.
Things related to supporting multiple interfaces should be
in the appropriate chapter, a BIG FAT note should be here about
this though and the recommendation to allow only a single
interface in STA mode at first!
!Finclude/net/mac80211.h ieee80211_vif
Receive and transmit processing
what should be here
TBD
This should describe the receive and transmit
paths in mac80211/the drivers as well as
transmit status handling.
Frame format
!Pinclude/net/mac80211.h Frame format
Packet alignment
!Pnet/mac80211/rx.c Packet alignment
Calling into mac80211 from interrupts
!Pinclude/net/mac80211.h Calling mac80211 from interrupts
functions/definitions
!Finclude/net/mac80211.h ieee80211_rx_status
!Finclude/net/mac80211.h mac80211_rx_flags
!Finclude/net/mac80211.h ieee80211_tx_info
!Finclude/net/mac80211.h ieee80211_rx
!Finclude/net/mac80211.h ieee80211_rx_ni
!Finclude/net/mac80211.h ieee80211_rx_irqsafe
!Finclude/net/mac80211.h ieee80211_tx_status
!Finclude/net/mac80211.h ieee80211_tx_status_ni
!Finclude/net/mac80211.h ieee80211_tx_status_irqsafe
!Finclude/net/mac80211.h ieee80211_rts_get
!Finclude/net/mac80211.h ieee80211_rts_duration
!Finclude/net/mac80211.h ieee80211_ctstoself_get
!Finclude/net/mac80211.h ieee80211_ctstoself_duration
!Finclude/net/mac80211.h ieee80211_generic_frame_duration
!Finclude/net/mac80211.h ieee80211_wake_queue
!Finclude/net/mac80211.h ieee80211_stop_queue
!Finclude/net/mac80211.h ieee80211_wake_queues
!Finclude/net/mac80211.h ieee80211_stop_queues
Frame filtering
!Pinclude/net/mac80211.h Frame filtering
!Finclude/net/mac80211.h ieee80211_filter_flags
The mac80211 workqueue
!Pinclude/net/mac80211.h mac80211 workqueue
!Finclude/net/mac80211.h ieee80211_queue_work
!Finclude/net/mac80211.h ieee80211_queue_delayed_work
Advanced driver interface
Information contained within this part of the book is
of interest only for advanced interaction of mac80211
with drivers to exploit more hardware capabilities and
improve performance.
Hardware crypto acceleration
!Pinclude/net/mac80211.h Hardware crypto acceleration
!Finclude/net/mac80211.h set_key_cmd
!Finclude/net/mac80211.h ieee80211_key_conf
!Finclude/net/mac80211.h ieee80211_key_flags
Powersave support
!Pinclude/net/mac80211.h Powersave support
Beacon filter support
!Pinclude/net/mac80211.h Beacon filter support
!Finclude/net/mac80211.h ieee80211_beacon_loss
Multiple queues and QoS support
TBD
!Finclude/net/mac80211.h ieee80211_tx_queue_params
Access point mode support
TBD
Some parts of the if_conf should be discussed here instead
Insert notes about VLAN interfaces with hw crypto here or
in the hw crypto chapter.
!Finclude/net/mac80211.h ieee80211_get_buffered_bc
!Finclude/net/mac80211.h ieee80211_beacon_get
Supporting multiple virtual interfaces
TBD
Note: WDS with identical MAC address should almost always be OK
Insert notes about having multiple virtual interfaces with
different MAC addresses here, note which configurations are
supported by mac80211, add notes about supporting hw crypto
with it.
Hardware scan offload
TBD
!Finclude/net/mac80211.h ieee80211_scan_completed
Rate control interface
TBD
This part of the book describes the rate control algorithm
interface and how it relates to mac80211 and drivers.
dummy chapter
TBD
Internals
TBD
This part of the book describes mac80211 internals.
Key handling
Key handling basics
!Pnet/mac80211/key.c Key handling basics
MORE TBD
TBD
Receive processing
TBD
Transmit processing
TBD
Station info handling
Programming information
!Fnet/mac80211/sta_info.h sta_info
!Fnet/mac80211/sta_info.h ieee80211_sta_info_flags
STA information lifetime rules
!Pnet/mac80211/sta_info.c STA information lifetime rules
Synchronisation
TBD
Locking, lots of RCU