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/share/man/man9/ieee80211_regdomain.9

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  2.\" Copyright (c) 2009 Sam Leffler, Errno Consulting
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 26.\" $FreeBSD$
 27.\"
 28.Dd August 4, 2009
 29.Dt IEEE80211_REGDOMAIN 9
 30.Os
 31.Sh NAME
 32.Nm ieee80211_regdomain
 33.Nd 802.11 regulatory support
 34.Sh SYNOPSIS
 35.In net80211/ieee80211_var.h
 36.In net80211/ieee80211_regdomain.h
 37.Pp
 38.Ft int
 39.Fo ieee80211_init_channels
 40.Fa "struct ieee80211com *"
 41.Fa "const struct ieee80211_regdomain *"
 42.Fa "const uint8_t bands[]"
 43.Fc
 44.\"
 45.Ft void
 46.Fo ieee80211_sort_channels
 47.Fa "struct ieee80211_channel *"
 48.Fa "int nchans"
 49.Fc
 50.\"
 51.Ft "struct ieee80211_appie *"
 52.Fn ieee80211_alloc_countryie "struct ieee80211com *"
 53.Sh DESCRIPTION
 54The
 55.Nm net80211
 56software layer provides a support framework for drivers that includes
 57comprehensive regulatory support.
 58.Nm net80211
 59provides mechanisms that enforce
 60.Em "regulatory policy"
 61by privileged user applications.
 62.Pp
 63Drivers define a device's capabilities and can
 64intercept and control regulatory changes requested through
 65.Nm net80211 .
 66The initial regulatory state, including the channel list, must be
 67filled in by the driver before calling
 68.Fn ieee80211_ifattach .
 69The channel list should reflect the set of channels the device is
 70.Em calibrated
 71for use on.
 72This list may also be requested later through the
 73.Vt ic_getradiocaps
 74method in the
 75.Vt ieee80211com
 76structure.
 77The
 78.Fn ieee80211_init_channels
 79function is provided as a rudimentary fallback for drivers that do not
 80(or cannot) fill in a proper channel list.
 81Default regulatory state is supplied such as the regulatory SKU,
 82ISO country code, location (e.g. indoor, outdoor), and a set of
 83frequency bands the device is capable of operating on.
 84.Nm net80211
 85populates the channel table in
 86.Vt ic_channels
 87with a default set of channels and capabilities.
 88Note this mechanism should be used with care as any mismatch between
 89the channel list created and the device's capabilities can result
 90in runtime errors (e.g. a request to operate on a channel the device
 91does not support).
 92The SKU and country information are used for generating 802.11h protocol
 93elements and related operation such as for 802.11d; mis-setup by a
 94driver is not fatal, only potentially confusing.
 95.Pp
 96Devices that do not have a fixed/default regulatory state can set
 97the regulatory SKU to
 98.Dv SKU_DEBUG
 99and country code to
100.Dv CTRY_DEFAULT
101and leave proper setup to user applications.
102If default settings are known they can be installed and/or an event
103can be dispatched to user space using
104.Fn ieee80211_notify_country
105so that
106.Xr devd 8
107will do the appropriate setup work at system boot (or device insertion).
108.Pp
109The channel table is sorted to optimize lookups using the
110.Fn ieee80211_sort_channels
111routine.
112This should be done whenever the channel table contents are modified.
113.Pp
114The
115.Fn ieee80211_alloc_countryie
116function allocates an information element as specified by 802.11h.
117Because this is expensive to generate it is cached in
118.Vt ic_countryie
119and generated only when regulatory state changes.
120Drivers that call
121.Fn ieee80211_alloc_countryie
122directly should not help with this caching; doing so may confuse the
123.Nm net80211
124layer.
125.Sh DRIVER REGULATORY CONTROL
126Drivers can control regulatory change requests by overriding the
127.Vt ic_setregdomain
128method that checks change requests.
129While drivers can reject any request that does not meet its requirements
130it is recommended that one be lenient in what is accepted and, whenever
131possible, instead of rejecting a request, alter it to be correct.
132For example, if the transmit power cap for a channel is too high the
133driver can either reject the request or (better) reduce the cap to be
134compliant.
135Requests that include unacceptable channels should cause the request
136to be rejected as otherwise a mismatch may be created between application
137state and the state managed by
138.Nm net80211 .
139The exact rules by which to operate are still being codified.
140.Sh SEE ALSO
141.Xr regdomain 5 ,
142.Xr ifconfig 8 ,
143.Xr ieee80211 9