On Thu, 02 Nov 2006 17:43:57 +0100
Johannes Berg [off-list ref] wrote:

On Thu, 2006-11-02 at 08:33 -0800, Simon Barber wrote:

quoted

There are many reasons to have the master device - and many reasons not
to get rid of it. The only excpetion is when using a limited fullmac
card.  Some fullmac cards only support a single ethernet interface, so
for these cards a single device may be OK, if we want to allow multiple
different appearences for different types of card (a bad thing in my
book). (Note - older prism 54g fullmac cards support WDS, hence need
multiple interfaces).

The master interface represents the physical networking device that
works using native 802.11 frames. The qdisc works on 802.11 frames - not
ethernet, and it can change how 802.11 management frames are queued. It
can only be got rid of in the case of a fullmac card with only a single
interface, where all management frames are processed in the card.

In addition as we move to make 802.11 devices native (i.e. create an
802.11 protocol) the 802.11 master interface will be essential.

While these are good points, I don't believe having the master interface
as a *netdev* is essential. In fact, it now has no functionality as a
netdev, if you try routing packets over it they're simply dropped.

It makes 802.11 packet capture easier as well.  Please don't invent yet
another network access object for the master device.

Of course we need some notion of the wireless PHY and cfg80211
explicitly represents that by assigning a wiphy index, but there's no
need for it to be a netdev.

johannes

-- 
Stephen Hemminger [off-list ref]