Date: Fri, 27 Nov 2015 19:08:47 -0800
From: Isaac Dunham <ibid.ag@gmail.com>
To: Natanael Copa <ncopa@alpinelinux.org>
Cc: alpine-devel@lists.alpinelinux.org
Subject: Re: [alpine-devel] alpine 3.3.0 rc1 released
Message-ID: <20151128030846.GA2529@newbook>
References: <20151126171801.32e233ba@ncopa-desktop.alpinelinux.org>
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In-Reply-To: <20151126171801.32e233ba@ncopa-desktop.alpinelinux.org>
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On Thu, Nov 26, 2015 at 05:18:01PM +0100, Natanael Copa wrote:
> Hi,
> 
> I am happy to announce that Alpine 3.3.0 first release candidate is released.

Glad to hear it!

[snip]
> Any other testing is also appreciated. Specially on different kind of
> hardware.

Well, I'd like to mention an issue I discovered on an Alpine Linux edge
system I'm using as a wireless router.
dmesg contains a lot of messages like these:
[   10.453071] cfg80211: Calling CRDA to update world regulatory domain
[   13.593462] cfg80211: Calling CRDA to update world regulatory domain
[   16.736817] cfg80211: Calling CRDA to update world regulatory domain
[   19.880084] cfg80211: Calling CRDA to update world regulatory domain
[   23.023427] cfg80211: Calling CRDA to update world regulatory domain
[   26.166723] cfg80211: Calling CRDA to update world regulatory domain
[   29.310142] cfg80211: Calling CRDA to update world regulatory domain
[   32.453458] cfg80211: Calling CRDA to update world regulatory domain
[   35.596777] cfg80211: Calling CRDA to update world regulatory domain
[   38.740183] cfg80211: Calling CRDA to update world regulatory domain
[   41.883462] cfg80211: Calling CRDA to update world regulatory domain
[   45.026808] cfg80211: Exceeded CRDA call max attempts. Not calling CRDA

Poking at it, I've found out the following:
* the 'regulatory domain' specifies the max power and channels for wireless.
* by default, it's the 'world regulatory domain': you are limited to the
channels and power usage which are allowed everywhere in the world.
* US regulatory domain (what I'd use) allows a bit more power.
* to properly set this, there are two ways:
 - install wireless-regdb and crda (neither packaged!), then set things up
 so that /sbin/crda is automatically run from your hotplug helper with
 COUNTRY=.. in your environment when cfg80211 triggers the proper uevent.
 Contrary to the lack of documentation, you can just run it from mdev
 whenever $COUNTRY is set, $ACTION=change, and $MODALIAS=platform:regulatory.
I used this line in mdev.conf (above $MODALIAS=...), but it may be overly
generic:

$COUNTRY=.. root:root 0660 */sbin/crda

 - fetch db.txt from wireless-regdb, drop it in net/wireless/db.txt in
 the linux source tree, and build the kernel with
CONFIG_CFG80211_INTERNAL_REGDB=y
 then add the proper module options to cfg80211.

Note that crda has a lot of confusion in the build system;
refer to Gentoo's ebuild for fixes.

Thanks,


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