Date: Thu, 16 Sep 2010 09:54:41 -1000
From: Jouni Malinen <j@w1.fi>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org
Subject: Re: [PATCH] mac80211: Filter ProbeReq SuppRates based on TX rate
 mask
Message-ID: <20100916195441.GB25174@jm.kir.nu>
References: <20100828163610.GA23426@jm.kir.nu>
 <1283154490.3691.2.camel@jlt3.sipsolutions.net>
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On Mon, Aug 30, 2010 at 09:48:10AM +0200, Johannes Berg wrote:
> On Sat, 2010-08-28 at 19:36 +0300, Jouni Malinen wrote:
> > If the TX rate set has been masked, the removed rates can also be
> > removed from the Supported Rates and Extended Supported Rates IEs in
> > Probe Request frames.
> 
> Technically, the probe request frame indicates RX bitrates. I don't
> really mind using the TX bitrates as well since typically I do think you
> probably want them to be symmetric, but shouldn't that come with nl80211
> updates etc. since that's all saying TX_BITRATES?

This change should really not be needed in the first place, but
unfortunately, P2P requires this for a compliant implementation.. The
field is really "Supported Rates", i.e., it would be used for both TX
and RX. I don't see any real point in configuring RX rates (i.e., make
hw not receive frames on one or more of the supported rates), so the TX
rate mask is the only reasonable configuration mechanism for this.

The minimum requirement (for P2P compliance) is to just remove rates 1,
2, 5.5, 11 Mbps from the list, so we could also add something to disable
802.11b rates in general if a different command would be desired.

-- 
Jouni Malinen                                            PGP id EFC895FA