Support for scan while in AP mode, and offchannel while in AP mode

[Avery Pennarun]

On Tue, Aug 19, 2014 at 11:23 AM, Adrian Chadd <adrian at freebsd.org> wrote:
> Yes. The whole point is that the firmware knows about the vdev and you
> set the channel on that. The intention is that there's multiple vdevs
> and if they're on different channels (eg STA + P2P, or STA + STA) then
> the firmware can handle channel changing, sending sleep notifications
> to the AP, buffering frames (well, pointers to frame data) so things
> don't get dropped, etc.
>
> I vaguely recall there being feature requests to do scanning in AP
> mode. It's a dirty hack, because yes you end up having packet loss
> during the scan for reasons I don't have to describe here, but you
> don't want it to be so bad that clients disassociate from you or end
> up having holes in the A-MPDU sequence space..

For my own purposes - scanning while the AP is running - the dirtiness
doesn't bother me *too* much.  Ideally I would like to request a
super-low-priority scan that only goes offchannel for short periods
but could take several (or even many) seconds to complete.  I gather
this is what the 'lowpri' option to 'iw ... scan' is for.