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NAME
SYNOPSIS
int
void
DESCRIPTIONThe Update calls should only be done when something changes that
affects the contents of the beacon frame. When this happens the
static void ath_beacon_update(struct ieee80211vap *vap, int item) { struct ieee80211_beacon_offsets *bo = &ATH_VAP(vap)->av_boff; setbit(bo->bo_flags, item); } with the
Devices that off-load beacon generation may instead choose to use this callback to push updates immediately to the device. Exactly how that is accomplished is unspecified. One possibility is to update the beacon frame contents and extract the appropriate information element, but other scenarios are possible. MULTI-VAP BEACON SCHEDULINGDrivers that support multiple vaps that can each beacon need to consider how to schedule beacon frames. There are two possibilities at the moment: burst all beacons at TBTT or stagger beacons over the beacon interval. Bursting beacon frames may result in aperiodic delivery that can affect power save operation of associated stations. Applying some jitter (e.g. by randomly ordering burst frames) may be sufficient to combat this and typically this is not an issue unless stations are using aggressive power save techniques such as U-APSD (sometimes employed by VoIP phones). Staggering frames requires more interrupts and device support that may not be available. Staggering beacon frames is usually superior to bursting frames, up to about eight vaps, at which point the overhead becomes significant and the channel becomes noticeably busy anyway. SEE ALSO
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