[PATCH 1/4] hostapd: add config option for dfs channels

[Simon Wunderlich]

Hello Helmut,

> On Thu, Feb 6, 2014 at 10:34 AM, Simon Wunderlich <sw at simonwunderlich.de> 
wrote:
> > Hello Helmut,
> > 
> >> On Wed, Feb 5, 2014 at 6:10 PM, Simon Wunderlich <sw at simonwunderlich.de>
> > 
> > wrote:
> >> > From: Simon Wunderlich <siwu at hrz.tu-chemnitz.de>
> >> > 
> >> > Different channels allow different transmission power, at least in
> >> > ETSI countries. Also, ETSI requires a "channel plan" for DFS
> >> > operation, and channels should be randomly choosen from these
> >> > channels.
> >> > 
> >> > Add a channel list configuration option for users to add channels
> >> > hostapd may pick from.
> >> > 
> >> > Signed-hostap: Simon Wunderlich <sw at simonwunderlich.de>
> >> > ---
> >> 
> >> [...]
> >> 
> >> > diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
> >> > index da7817f..7591663 100644
> >> > --- a/hostapd/hostapd.conf
> >> > +++ b/hostapd/hostapd.conf
> >> > @@ -140,6 +140,12 @@ channel=1
> >> > 
> >> >  # Defaults:
> >> >  #acs_num_scans=5
> >> > 
> >> > +# DFS Channels. This option allows hostapd to select on of the
> >> > provided +# DFS Channels when the current channels becomes
> >> > unavailable due to +# radar interference. Only useful when
> >> > ieee80211h=1 is set.
> >> > +# Default: not set
> >> > +#dfs_chanlist=100 104 108 112 116
> >> > +
> >> 
> >> Would it make sense to also use this for automatic channel selection?
> >> So, instead of just using it for DFS channel switching we might use the
> >> same list to restrict ACS to a subset of channels?
> >> In that case however this should have a more generic name like
> >> "chanlist".
> > 
> > That might be useful indeed, although I'm not familiar with ACS and don't
> > plan to work on it. If you want, I can change the parameter name to
> > chanlist as you suggest and leave the ACS part to someone else?
> 
> I think that makes sense. The comments can still point out DFS for now but
> it would allow to reuse the chanlist config item for ACS in the future.

OK, sounds reasonable, I'll prepare v2.

> 
> To allow DFS to switch to a non-DFS channel (like 36) would that channel
> have to be in the channel list?

Yes, exactly. This channel list is considered by the DFS channel selection 
code, which is called if a channel is/becomes unavailable (e.g. due to radar).

Cheers,
    SImon