On 20 February 2014 08:08, Johannes Berg [off-list ref] wrote:

On Thu, 2014-02-20 at 07:07 +0100, Janusz Dziedzic wrote:

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What happens if an old kernel gets a new wireless-regdb with AUTO on
all of its 5 GHz regdomain for the country it using ? I see no mention
of this anywhere in the documentation and at least from the code
review I just did it seemed like we'd use 0. I hope I'm wrong as
otherwise that'd introduce a severe regression when this is introduced
to wireless-regdb.

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Old-kernel + new wireless-regdb + new crda.
In case of AUTO we will not set NL80211_ATTR_FREQ_RANGE_MAX_BW we will
get -EINVAL

That seems like a problem.

So, we can always add NL80211_ATTR_FREQ_RANGE_MAX_BW set as 0 in crda.
Then all channels where BW=0 will be HT20 only for old kernel.

BR
Janusz