From: Erwin Van de Velde <erwin.vandevelde@gmail.com>
To: linux-wireless <linux-wireless@vger.kernel.org>
Cc: Julian Calaby <julian.calaby@gmail.com>,
	Schrober <franzschrober@yahoo.de>
Subject: Re: ath9k bug in country domain handling
Date: Sun, 17 Jun 2012 19:12:29 +0200
Message-ID: <1416482.lsS5g7Br9z@sylvesterjr.cmi.ua.ac.be> (sfid-20120617_191304_706591_B64F9CE6)
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Hi,

On Sunday 17 June 2012 12:15:47 Julian Calaby wrote:
> There are two places where the country codes and their associated
> restrictions come from:
> 1. The user, by saying "iw reg set XX" or having some other program
> set that for them.
> 2. The driver, by asking the card which country it's been configured for.
> 
> The kernel regulatory framework then takes these two sets of
> regulatory data, finds the intersection of them, and restricts the
> channels and options available for the card based on that.
> 
> Why?
> 
> I'm not sure of the exact details, but I know that most wireless cards
> are configured, by which I mean calibrated, adjusted and tuned to work
> in a particular country. Some are configured for the entire world, but
> most are configured for a single country's requirements. The driver
> cannot assume that if it asks the card to do anything outside the
> country it's been configured for, that it will perform predictably.
> So, for example, if the driver asks your card to use a channel that is
> outside the US's regulatory requirements, the driver cannot guarantee
> that, even if it instructs the card how to use that channel correctly,
> it will actually use that channel in a manner consistent with
> Belgium's regulatory requirements.
> 
> The driver's behaviour when it encounters the unset regulatory
> information on the card will be to use the default information for
> that card. Which in this case is the US regulatory restrictions.
> 
> I hate to say it, but the issue here is *not* the driver itself. The
> supplier of that card has not set it up correctly for Belgium, and the
> driver is compensating for that as best as it can.
> 
> I have a similar card at home in Australia, it's configured for use in
> China, and thankfully the intersection of China's and Australia's
> regulatory requirements are such that I can use it for the purpose I
> purchased it for.
> 

Ow., this is new to me. Thanks a lot for the explanation, now I see why things 
are like they are!

Thanks a lot!
Erwin