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From: Arik Nemtsov <arik@wizery.com>
Date: Thu, 13 Nov 2014 17:55:13 +0200
Message-ID: <CA+XVXfd-Z-mv7iL-Og=_Spr053HgW8pZXMR3jmbaQc-jX7v3-g@mail.gmail.com> (sfid-20141113_165534_251264_E031F53D)
Subject: Re: [PATCH 5/5] cfg80211: Allow usermode to query wiphy specific regd info
To: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>
Cc: "Luis R. Rodriguez" <mcgrof@suse.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Jonathan Doron <jond@wizery.com>
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Sender: linux-wireless-owner@vger.kernel.org

>
>> 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.

Arik