[ath9k-devel] Questions about virtual managed interfaces.

[Ben Greear <greearb@candelatech.com>]

I'm trying to understand the features and limitations of the ath9k
virtual phy and virtual station support.  I'm using the 2.6.34 kernel.

First, I was able to create new virtual phys with the
echo add > /debug/ath9k/phy1/wiphy
logic.

That seems to work OK, and a new wlanX interface is created.

The first potential problem I see is that the wlanX interfaces
have the same MAC.  A previous post to this list made it appear
that they would be XORd with phy-id or similar to get a unique
MAC?

It does appear that I can set the MAC address using 'ip link set ...', but I'm
not sure if that is the right approach.

I also tried adding new managed interfaces using
iw phy phy1 interface add wlan1-1 type managed

This also seems to work in as far as a new interface is created.

Now, I am curious about configuring these things.

*  If I have two managed wlans on the same phy, I assume they must
    both be on the same channel?  Is there any support in the driver
    to make sure that once one interface is associated on a particular
    channel that another interface cannot start scanning on different channels
    (and thus disrupt the first one)?

    In some previous hackings of virtual station interfaces on ath5k, we
    had all sorts of issues getting a bunch of interfaces associated
    when using wpa-supplicant because one would start scanning and that would
    dis-associate the others..over and over.

*  If I want, say, 128 virtual station interfaces, does it make sense to try
    to use 128 virtual phys, or should I aim at multiple stations per phy?

    If anyone has tested the upper limits of how many virtual phys and/or
    stations can be supported, I'm interested to know!

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com