Default Interface Bringup

Oliver Grawert ogra at
Tue Dec 29 11:31:19 UTC 2015

Am Montag, den 28.12.2015, 16:33 -0800 schrieb Manik Taneja:
> Guys,
> I was working on the Thin Canyon NUC and noticed that by default we
> don't bring up wlan0 interface. Instead, the only interface brought
> up is eth0. I checked this behavior on the Dragonboard 410c and
> noticed that we don't bring up the wlan0 interface as well. Is this
> behavior by design? On both the boards, I was able to bring up the
> interfaces by using-
> sudo ifconfig wlan0 up
> however, the command-
> sudo ifup wlan0 fails with ifup: Ignoring unkown interface:
> wlan0=wlan0
> Can someone please help me understand what's the reason for this?
> Also, If we have the kernel module for wifi available than why don't
> we enable the wlan0 interface by default? I think that's a much
> cleaner interface for someone starting with Snappy.

the problem here is that you need additional authentication data in
your interfaces file to make wlan0 work out of the box, while you only
need to enable dhcp for wired interfaces (well, we could just hope for
the best and leave it without WEP credentials, hoping that the user has
a fully open WLAN, but i assume such networks are to rare to rely on
them for a default ...)

we either need a way to tell ubuntu-device-flash to use a config file
as input for such defaults (some yaml file that gets handed to "snappy
config ubuntu-core" on first boot) or ask the user to create his own
gadget snap with the network password inside ... or make the tty
console work on all devices and properly document what you need to do
to get your wlan up ...

my next dragonboard image has the tty console on by default given the
dragonboard doesnt have any other interface but wlan by default, that
will at least prevent you from having to buy a serial addon board to
get up and running ... 

long term we need a solution for these pre-installation defaults (there
is also the console= commandline option for which we can not really
choose a sane default (in IoT you will want to use serial, while for
the same device in a server setup you might want a tty console as
default output, such settings are totally context dependant ... ))


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