static/freebsd/man9/ieee80211_input.9 3.html


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<table class="head">
  <tr>
    <td class="head-ltitle">IEEE80211_INPUT(9)</td>
    <td class="head-vol">Kernel Developer's Manual</td>
    <td class="head-rtitle">IEEE80211_INPUT(9)</td>
  </tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">ieee80211_input</code> &#x2014;
    <span class="Nd">software 802.11 stack input functions</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="In">#include
    &lt;<a class="In">net80211/ieee80211_var.h</a>&gt;</code></p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">ieee80211_input</code>(<var class="Fa">struct ieee80211_node
    *</var>, <var class="Fa">struct mbuf *</var>, <var class="Fa">int
    rssi</var>, <var class="Fa">int noise</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">ieee80211_input_all</code>(<var class="Fa">struct
    ieee80211com *</var>, <var class="Fa">struct mbuf *</var>,
    <var class="Fa">int rssi</var>, <var class="Fa">int noise</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">net80211</code> layer that supports 802.11
    device drivers requires that receive processing be single-threaded.
    Typically this is done using a dedicated driver
    <a class="Xr">taskqueue(9)</a> thread.
    <a class="permalink" href="#ieee80211_input"><code class="Fn" id="ieee80211_input">ieee80211_input</code></a>()
    and
    <a class="permalink" href="#ieee80211_input_all"><code class="Fn" id="ieee80211_input_all">ieee80211_input_all</code></a>()
    process received 802.11 frames and are designed for use in that context;
    e.g. no driver locks may be held.</p>
<p class="Pp">The frame passed up in the <var class="Vt">mbuf</var> 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
    <a class="Xr">ip(4)</a>.</p>
<p class="Pp">If a device (such as <a class="Xr">ath(4)</a>) inserts padding
    after the 802.11 header to align the payload to a 32-bit boundary the
    <code class="Dv">IEEE80211_C_DATAPAD</code> capability must be set.
    Otherwise header and payload are assumed contiguous in the mbuf chain.</p>
<p class="Pp">If a received frame must pass through the A-MPDU receive reorder
    buffer then the mbuf must be marked with the <code class="Dv">M_AMPDU</code>
    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
    <code class="Dv">IEEE80211_NODE_HT</code> in the
    <var class="Vt">ni_flags</var> of the station's node table entry, any frames
    that do not require reorder processing will be dispatched with only minimal
    overhead.</p>
<p class="Pp">The <var class="Vt">rssi</var> parameter is the Receive Signal
    Strength Indication of the frame measured in 0.5dBm units relative to the
    noise floor. The <var class="Vt">noise</var> 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 <code class="Nm">net80211</code>
    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).</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
  ALSO</a></h1>
<p class="Pp"><a class="Xr">ieee80211(9)</a></p>
</section>
</div>
<table class="foot">
  <tr>
    <td class="foot-date">August 4, 2009</td>
    <td class="foot-os">FreeBSD 15.0</td>
  </tr>
</table>