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+.\"
+.\" Copyright (c) 2004 Bruce M. Simpson <bms@spc.org>
+.\" Copyright (c) 2004 Darron Broad <darron@kewl.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd August 4, 2009
+.Dt IEEE80211_INPUT 9
+.Os
+.Sh NAME
+.Nm ieee80211_input
+.Nd software 802.11 stack input functions
+.Sh SYNOPSIS
+.In net80211/ieee80211_var.h
+.Ft void
+.Fo ieee80211_input
+.Fa "struct ieee80211_node *"
+.Fa "struct mbuf *"
+.Fa "int rssi"
+.Fa "int noise"
+.Fc
+.Ft void
+.Fo ieee80211_input_all
+.Fa "struct ieee80211com *"
+.Fa "struct mbuf *"
+.Fa "int rssi"
+.Fa "int noise"
+.Fc
+.Sh DESCRIPTION
+The
+.Nm net80211
+layer that supports 802.11 device drivers requires that
+receive processing be single-threaded.
+Typically this is done using a dedicated driver
+.Xr taskqueue 9
+thread.
+.Fn ieee80211_input
+and
+.Fn ieee80211_input_all
+process received 802.11 frames and are designed
+for use in that context; e.g. no driver locks may be held.
+.Pp
+The frame passed up in the
+.Vt mbuf
+must have the 802.11 protocol header at the front; all device-specific
+information and/or PLCP must be removed.
+Any CRC must be stripped from the end of the frame.
+The 802.11 protocol header should be 32-bit aligned for
+optimal performance but receive processing does not require it.
+If the frame holds a payload and that is not aligned to a 32-bit
+boundary then the payload will be re-aligned so that it is suitable
+for processing by protocols such as
+.Xr ip 4 .
+.Pp
+If a device (such as
+.Xr ath 4 )
+inserts padding after the 802.11 header to align
+the payload to a 32-bit boundary the
+.Dv IEEE80211_C_DATAPAD
+capability must be set.
+Otherwise header and payload are assumed contiguous in the mbuf chain.
+.Pp
+If a received frame must pass
+through the A-MPDU receive reorder buffer then the mbuf
+must be marked with the
+.Dv M_AMPDU
+flag.
+Note that for the moment this is required of all frames received from
+a station and TID where a Block ACK stream is active, not just A-MPDU
+aggregates.
+It is sufficient to check for
+.Dv IEEE80211_NODE_HT
+in the
+.Vt ni_flags
+of the station's node table entry, any frames that do not require reorder
+processing will be dispatched with only minimal overhead.
+.Pp
+The
+.Vt rssi
+parameter is the Receive Signal Strength Indication of the frame
+measured in 0.5dBm units relative to the noise floor.
+The
+.Vt noise
+parameter is the best approximation of the noise floor in
+dBm units at the time the frame was received.
+RSSI and noise are used by the
+.Nm net80211
+layer to make scanning and roaming decisions in station mode
+and to do auto channel selection for hostap and similar modes.
+Otherwise the values are made available to user applications
+(with the rssi presented as a filtered average over the last ten values
+and the noise floor the last reported value).
+.Sh SEE ALSO
+.Xr ieee80211 9