Subject: Re: wireless: recap of current issues (configuration)

From: Krzysztof Halasa <[email-masked]>
Date: Sat, 14 Jan 2006 01:05:59 +0100

"John W. Linville" <[email-masked]> writes:

> Virtual devices will have a mode (e.g. station, AP, WDS, ad-hoc, rfmon,
> raw?, other modes?) which defines its "on the air" behaviour.  Should
> this mode be fixed when the wlan device is created?

I think so. If needed one can delete and create.

>  Or something
> that can be changed when the net_device is down?

IMHO: unnecessary complicates things.

> It may be necessary to remove, suspend, and/or disable wlan devices
> in order to add, resume, and/or enable other types of wlan devices
> on the same WiPHY device (especialy true for rfmon).  A mechanism is
> needed for drivers to be able to influence or disallow combinations
> of wlan devices in accordance with capabilities of the hardware.

If the control messages go through the main (WiPHY) driver it can
decide and/or forward the request further, to the library.

Not sure about netlink. OTOH I'm at all not sure netlink should be
used for configuration. sysfs, ioctl seem a better options. Netlink
is better for state monitoring etc. I don't know it very well though.

> Do "global" config requests go to any associated wlan device?

Are they any global config settings?
sysctl or sysfs maybe?

> Or must they be directed to the WiPHY device?  Does it matter?

If you mean "settings for a particular physical card" then WiPHY.

> I think we should require "global" configuration to target the WiPHY
> device, while "local" configuration remains with the wlan device.

If "local" means "concerning the wlan device" then sure, yes.

> (I'm not sure how important this point is?)  Either way, the WiPHY
> device will need some way to be able to reject configuration requests
> that are incompatible among its associated wlan devices.  Since the
> wlan interface implementations should not be device specific, perhaps
> the 802.11 stack can be smart enough to filter-out most conflicting
> config requests before they get to the WiPHY device?

I don't think so. The hardware driver should get the request first,
the rest should look like a library.

I've played with both approaches for years and I would avoid
"802.11 using the hw driver" scenario if at all possible.
-- 
Krzysztof Halasa