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NAME

     ieee80211_regdomain -- 802.11 regulatory support

SYNOPSIS

     #include <net80211/ieee80211_var.h>
     #include <net80211/ieee80211_regdomain.h>

     int
     ieee80211_init_channels(struct ieee80211com *,
         const struct ieee80211_regdomain *, const uint8_t bands[]);

     void
     ieee80211_sort_channels(struct ieee80211_channel *, int nchans);

     struct ieee80211_appie *
     ieee80211_alloc_countryie(struct ieee80211com *);

DESCRIPTION

     The net80211 software layer provides a support framework for drivers that
     includes comprehensive regulatory support.  net80211 provides mechanisms
     that enforce regulatory policy by privileged user applications.

     Drivers define a device's capabilities and can intercept and control
     regulatory changes requested through net80211.  The initial regulatory
     state, including the channel list, must be filled in by the driver before
     calling ieee80211_ifattach().  The channel list should reflect the set of
     channels the device is calibrated for use on.  This list may also be
     requested later through the ic_getradiocaps method in the ieee80211com
     structure.  The 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.  net80211
     populates the channel table in 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.

     Devices that do not have a fixed/default regulatory state can set the
     regulatory SKU to SKU_DEBUG and country code to 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
     ieee80211_notify_country() so that devd(8) will do the appropriate setup
     work at system boot (or device insertion).

     The channel table is sorted to optimize lookups using the
     ieee80211_sort_channels() routine.  This should be done whenever the
     channel table contents are modified.

     The ieee80211_alloc_countryie() function allocates an information element
     as specified by 802.11h.  Because this is expensive to generate it is
     cached in ic_countryie and generated only when regulatory state changes.
     Drivers that call ieee80211_alloc_countryie() directly should not help
     with this caching; doing so may confuse the net80211 layer.

DRIVER REGULATORY CONTROL

     Drivers can control regulatory change requests by overriding the
     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 net80211.  The exact rules by which to operate are still
     being codified.

SEE ALSO

     regdomain(5), ifconfig(8), ieee80211(9)