Date: Tue, 8 Dec 2009 10:59:52 -0800
From: Stephen Hemminger <shemminger@vyatta.com>
To: "Luis R. Rodriguez" <mcgrof@gmail.com>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org, linux-hotplug@vger.kernel.org
Subject: Re: wireless device and udev
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On Tue, 8 Dec 2009 10:50:30 -0800
"Luis R. Rodriguez" <mcgrof@gmail.com> wrote:

> On Tue, Dec 8, 2009 at 10:43 AM, Stephen Hemminger
> <shemminger@vyatta.com> wrote:
> > On Tue, 8 Dec 2009 09:29:40 -0500
> > "John W. Linville" <linville@tuxdriver.com> wrote:
> >
> >> On Mon, Dec 07, 2009 at 05:26:16PM -0800, Stephen Hemminger wrote:
> >> > The default udev persistent network rules based on hardware mac id doesn't
> >> > work well when multiple SSID's are created on an access-point.  The command
> >> >  iw phy phy0 interface add wlan1 type managed
> >> >
> >> > is supposed to make a device name wlan1, but udev sees that it has the same
> >> > mac address as wlan0 and gets confused leaving the device named wlan1_rename
> >> >
> >> > It looks like wlanX is breaking assumptions of existing udev persistent network
> >> > device name generation rules.  Perhaps there needs to be special case for wlanX
> >> > devices?
> >>
> >> Yes, probably so.  But what would it be?  Factoring-in SSID is clearly
> >> not right for the usual case (i.e. one interface on a mobile device).
> >> I'm not sure what else one could use as a key.
> >>
> >> What does udev do for bridge, bond, or vlan devices?  Don't those
> >> share MAC addresses with the underlying physical device?
> >>
> >> John
> >
> > At least on ubuntu/debian the name whitelist is:
> >
> >
> > # device name whitelist
> > KERNEL!="eth*|ath*|wlan*[0-9]|msh*|ra*|sta*|ctc*|lcs*|hsi*", GOTO="persistent_net_generator_end"
> >
> > So bond or bridge don't match and don't get tampered with.
> >
> > The problem is that wlan* device names are used for both hardware and virtual
> > devices.  Udev scripts can be fixed "do the right thing" but there is not sufficient
> > information for the script to decide how to attach persistent name.
> > What values from sysfs (ie attributes) should script be using?  This probably
> > means that additional attributes needed to be added to wireless device infrastructure
> > in kernel.
> 
> We could likely use the new SET_NETDEV_DEVTYPE() but I have yet to see
> where this is exported. It must be there somewhere.

Both devices would have same type? don't see how that would help

Imagine a system with two Atheros cards, and 2 SSID's per card.
How would devices be identified by udev to assign persistent name?