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27 .\" $FreeBSD: src/share/man/man9/ieee80211_input.9,v 1.5 2009/09/18 00:33:47 brueffer Exp $
34 .Nd software 802.11 stack input functions
38 .In netproto/802_11/ieee80211_var.h
41 .Fa "struct ieee80211_node *"
47 .Fo ieee80211_input_all
48 .Fa "struct ieee80211com *"
56 layer that supports 802.11 device drivers requires that
57 receive processing be single-threaded.
58 Typically this is done using a dedicated driver
63 .Fn ieee80211_input_all
64 process received 802.11 frames and are designed
65 for use in that context; e.g. no driver locks may be held.
67 The frame passed up in the
69 must have the 802.11 protocol header at the front; all device-specific
70 information and/or PLCP must be removed.
71 Any CRC must be stripped from the end of the frame.
72 The 802.11 protocol header should be 32-bit aligned for
73 optimal performance but receive processing does not require it.
74 If the frame holds a payload and that is not aligned to a 32-bit
75 boundary then the payload will be re-aligned so that it is suitable
76 for processing by protocols such as
81 inserts padding after the 802.11 header to align
82 the payload to a 32-bit boundary the
83 .Dv IEEE80211_C_DATAPAD
84 capability must be set.
85 Otherwise header and payload are assumed contiguous in the mbuf chain.
87 If a received frame must pass
88 through the A-MPDU receive reorder buffer then the mbuf
89 must be marked with the
92 Note that for the moment this is required of all frames received from
93 a station and TID where a Block ACK stream is active, not just A-MPDU
95 It is sufficient to check for
99 of the station's node table entry, any frames that do not require reorder
100 processing will be dispatched with only minimal overhead.
104 parameter is the Receive Signal Strength Indication of the frame
105 measured in 0.5dBm units relative to the noise floor.
108 parameter is the best approximation of the noise floor in
109 dBm units at the time the frame was received.
110 RSSI and noise are used by the
112 layer to make scanning and roaming decisions in station mode
113 and to do auto channel selection for hostap and similar modes.
114 Otherwise the values are made available to user applications
115 (with the rssi presented as a filtered average over the last ten values
116 and the noise floor the last reported value).