Date: Wed, 2 Feb 2011 15:38:39 +0200
From: Jouni Malinen <j@w1.fi>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Bob Copeland <me@bobcopeland.com>,
	"Luis R. Rodriguez" <mcgrof@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	linux-kernel@vger.kernel.org, Amod Bodas <Amod.Bodas@atheros.com>,
	Senthilkumar Balasubramanian
	<Senthilkumar.Balasubramanian@atheros.com>,
	Sree Durbha <Sree.Durbha@atheros.com>,
	Deepak Dhamdhere <Deepak.Dhamdhere@atheros.com>,
	Xin Jin <Xin.Jin@atheros.com>
Subject: Re: Support for Android for mac80211 / cfg80211 802.11 drivers
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On Wed, Feb 02, 2011 at 12:33:54PM +0100, Johannes Berg wrote:
> What's the driver_cmd things they use? If we they add support for
> whatever it is to nl80211, why can those not be normal supplicant
> interfaces?

I have not reviewed what exactly gets used and how, so this is only
based on what the modification for wpa_supplicant are exposing.

There seems to be some kind of mechanism for stopping/starting/reloading
the driver which I do not fully understand. It includes some kind of
driver hang detection and maybe recovery from that etc..

Then there is a very generic mechanism of passing any command from user
space (i.e., command string to a SIOCSIWPRIV) and that goes
transparently through wpa_supplicant.. The response comes back as a
string. In other words, you could implement pretty much anything in a
driver specific way with that.. At least following commands are used or
have used with that: RSSI, LINKSPEED, MACADDR, GETPOWER, GETBAND.

Since it is difficult to tell just from wpa_supplicant changes what
exactly is done with these interfaces, the answer to the question of
why these could not be normal supplicant interfaces is not immediately
clear to me. I would assume that some of this functionality could
certainly be added once identified clearly what is needed. Some may
already be available (like MACADDR; assuming it is used to fetch local
MAC address).

-- 
Jouni Malinen                                            PGP id EFC895FA