[systemd-devel] udev breaks hostap linkage of raw/user interfaces, causing wpa_supplicant problems

[Tom Gundersen]

On Mon, Mar 16, 2015 at 10:34 AM, Thomas Richter <thor at math.tu-berlin.de> wrote:
> The laptop in question had a ipw2200 card installed, which was
> configured by udev as wlan0 (obviously). This card got replaced
> (basically, due to another bug in ipw2200 which is unrelated to udev),
> and "obviously" udev picked a new name for the adapter, which now became
> wlan1. Unfortunately, udev *did not* change the name of the raw radio
> (wifi0), which should have become wifi1 to make wpa_supplicant happy.

udev would never pick the names wlan0 or wlan1 automatically, this is
not how it (ever) worked. wlan0 and wlan1 are the sort of names the
kernel sets, and at most udev (in very old versions) might have tried
to remember these names between reboots and reapply them. This scheme
is no longer in place though, so unless your distro is shipping some
non-standard stuff or you have some old rule files lying around in
/etc/udev/rules.d you should not be affected by that (and even if you
are, I don't see how this would cause your current problem).

Are you sure that udev is even renaming your devices at all? Booting
with debug logging will tell you. You should see "Renamed network
interface 'foo' to 'bar'" in your logs.

Cheers,

Tom