Date: Thu, 13 Nov 2014 20:05:38 +0100
From: "Luis R. Rodriguez" <mcgrof@suse.com>
To: Arik Nemtsov <arik@wizery.com>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Jonathan Doron <jond@wizery.com>
Subject: Re: [PATCH 5/5] cfg80211: Allow usermode to query wiphy specific
	regd info
Message-ID: <20141113190538.GC24486@wotan.suse.de> (sfid-20141113_200543_900704_96B17A8A)
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On Thu, Nov 13, 2014 at 05:55:13PM +0200, Arik Nemtsov wrote:
> >
> >> 2. And then if userspace sends a wiphy idx to the NL80211_CMD_GET_REG,
> >> we'll return wiphy->regd for that case as well?
> >
> > That's right, for now we'd be able to send the regd when either
> > NL80211_ATTR_WIPHY_SELF_MANAGED_REG is set or when
> > NL80211_ATTR_WIPHY_SELF_MANAGED_REG is not set but regulatory_hint()
> > was used. Note that some users may have REGULATORY_CUSTOM_REG. and
> > then later use regulatory_hint(), this is done to for example set a
> > more restrictive custom world regdomain and then later use the CRDA
> > data for a specific alpha2.
> 
> Well always sending wiphy->regd whenever it is set is easy, but it
> might be problematic I guess:
> 
> We intend to add a patch to wpa_s to always add the wiphy_idx to
> NL80211_CMD_GET_REG. With the current approach only drivers with
> SELF_MANAGED_REG will get wiphy->regd back. This is ok since these are
> new drivers, which are familiar with this API.
> 
> But if we use your suggestion and always return wiphy->regd, then some
> driver like ath9k that uses regulatory_hint() will now get it's
> private regd returned to the wpa_s that manages it. I'm not saying
> it's necessarily bad, but it's different than what was returned
> before. The cfg80211 regdomain is intersected with wiphy->regd, so now
> ath9k will start getting more permissive channels in usermode.
> 
> So we thought it's best to enable the new behavior only if the driver
> explicitly wants it, using a new regulatory flag.

There's two userspace APIs:

iw reg get


That should return the cfg80211 regdomain and then traverse through all
the wiphy and if they have a wiphy->regd it should return that and also
a qualifier that specifies how that wiphy->regd got there.

iw rege get dev wlan0

That will only get the wiphy->regd for wlan0 and the qualifier that
identifies how it was set.

With the qualifier userspace should be able to do different things
and that should address letting you do something different per
different wiphy->regd on userspace, no?

  Luis