Re: [PATCH 2/4] nl80211/cfg80211: enable DFS for IBSS mode

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

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On Tue, Oct 01, 2013 at 01:09:17PM +0200, Johannes Berg wrote:
> On Tue, 2013-09-03 at 19:43 +0200, Simon Wunderlich wrote:
> > To use DFS in IBSS mode, userspace is required to react to radar events.
> > It can inform nl80211 that it is capable of doing so by adding a
> > NL80211_ATTR_CONTROL_PORT_DFS attribute when joining the IBSS.
> 
> I don't like that name, it makes no sense. This has nothing to do with
> the port control (802.1X-style) at all.
> 

How about NL80211_ATTR_DFS_CAPABLE instead?


> > If this attribute is supplied, DFS channels may be used if the driver
> > supports it. Support will be checked even if a channel without DFS will
> > be joined, as the channel might change later due to scan activity or
> > channel switch announcements.
> 
> You also really should document *what* is required of userspace here.
> You're kinda saying this needs to be implemented, but not saying what
> needs to be done. I can't even tell - what does it really have to do?

Yeah, I should document this a little more: Userspace should react to
radar events and apprioately switch the channel when this happens. As
non-capable tools (like wpa_supplicant in it's current state) do not
react on radar events but might select DFS channels when available, there
might be non-conforming behaviour. Therefore I'm introducing this flag.

Userspace programs are supposed to set this flag when they have channel
management and radar avoidance/channel change functionality is implemented
to unlock DFS channels.

> Don't you implement most of it in patches 3 and 4 anyway in the kernel?

Nope, I don't.

I can resend the patchset with some more documentation on this.

Thanks,
	Simon

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