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)

Debian                                           August 4, 2009                           IEEE80211_REGDOMAIN(9)