freebsd-dev/share/man/man9/ieee80211_regdomain.9

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.Dd August 4, 2009
.Dt IEEE80211_REGDOMAIN 9
.Os
.Sh NAME
.Nm ieee80211_regdomain
.Nd 802.11 regulatory support
.Sh SYNOPSIS
.In net80211/ieee80211_var.h
.In net80211/ieee80211_regdomain.h
.Pp
.Ft int
.Fo ieee80211_init_channels
.Fa "struct ieee80211com *"
.Fa "const struct ieee80211_regdomain *"
.Fa "const uint8_t bands[]"
.Fc
.\"
.Ft void
.Fo ieee80211_sort_channels
.Fa "struct ieee80211_channel *"
.Fa "int nchans"
.Fc
.\"
.Ft "struct ieee80211_appie *"
.Fn ieee80211_alloc_countryie "struct ieee80211com *"
.Sh DESCRIPTION
The
.Nm net80211
software layer provides a support framework for drivers that includes
comprehensive regulatory support.
.Nm net80211
provides mechanisms that enforce
.Em "regulatory policy"
by privileged user applications.
.Pp
Drivers define a device's capabilities and can
intercept and control regulatory changes requested through
.Nm net80211 .
The initial regulatory state, including the channel list, must be
filled in by the driver before calling
.Fn ieee80211_ifattach .
The channel list should reflect the set of channels the device is
.Em calibrated
for use on.
This list may also be requested later through the
.Vt ic_getradiocaps
method in the
.Vt ieee80211com
structure.
The
.Fn ieee80211_init_channels
function is provided as a rudimentary fallback for drivers that do not
(or cannot) fill in a proper channel list.
Default regulatory state is supplied such as the regulatory SKU,
ISO country code, location (e.g. indoor, outdoor), and a set of
frequency bands the device is capable of operating on.
.Nm net80211
populates the channel table in
.Vt ic_channels
with a default set of channels and capabilities.
Note this mechanism should be used with care as any mismatch between
the channel list created and the device's capabilities can result
in runtime errors (e.g. a request to operate on a channel the device
does not support).
The SKU and country information are used for generating 802.11h protocol
elements and related operation such as for 802.11d; mis-setup by a
driver is not fatal, only potentially confusing.
.Pp
Devices that do not have a fixed/default regulatory state can set
the regulatory SKU to
.Dv SKU_DEBUG
and country code to
.Dv CTRY_DEFAULT
and leave proper setup to user applications.
If default settings are known they can be installed and/or an event
can be dispatched to user space using
.Fn ieee80211_notify_country
so that
.Xr devd 8
will do the appropriate setup work at system boot (or device insertion).
.Pp
The channel table is sorted to optimize lookups using the
.Fn ieee80211_sort_channels
routine.
This should be done whenever the channel table contents are modified.
.Pp
The
.Fn ieee80211_alloc_countryie
function allocates an information element as specified by 802.11h.
Because this is expensive to generate it is cached in
.Vt ic_countryie
and generated only when regulatory state changes.
Drivers that call
.Fn ieee80211_alloc_countryie
directly should not help with this caching; doing so may confuse the
.Nm net80211
layer.
.Sh DRIVER REGULATORY CONTROL
Drivers can control regulatory change requests by overriding the
.Vt ic_setregdomain
method that checks change requests.
While drivers can reject any request that does not meet its requirements
it is recommended that one be lenient in what is accepted and, whenever
possible, instead of rejecting a request, alter it to be correct.
For example, if the transmit power cap for a channel is too high the
driver can either reject the request or (better) reduce the cap to be
compliant.
Requests that include unacceptable channels should cause the request
to be rejected as otherwise a mismatch may be created between application
state and the state managed by
.Nm net80211 .
The exact rules by which to operate are still being codified.
.Sh SEE ALSO
.Xr regdomain 5 ,
.Xr ifconfig 8 ,
.Xr ieee80211 9