Friday, 13 December 2013

urfkill : a daemon to centrally control RF killswitches

Here's another project of the u-daemon variety. The latest addition to upower, udev, etc. Meet urfkill.

urfkill is meant to be a daemon that centralizes killswitch handling, rather than having all kind of different applications and daemon handle Wi-Fi, Bluetooth, WWAN and whatnot separately, and potentially fighting over them, you can have just one system that tracks the states and makes it possible to switch just one type of killswitch on all at one, or turn everything off should you so desire...

One reason I've taken an interest in urfkill in Ubuntu is that as we build a phone, we have to keep thinking about how users of the devices will be mobile. That's even more the case when you think about a phone or tablet than a laptop: on a laptop, you may have to think of WiFi and Bluetooth, but you're just about as likely to have your laptop off or not have it at all; whereas phones and tablets have become ubiquitous in our way of life.

Like anyone, thinking mobile I'd first think of walking around, driving, or other methods of travel. Granted, nobody needs to turn off Wi-Fi when getting in their car, but what about on planes?

This is the first thing everything brings up when talking about killswitches. Planes. Alright, you really do need to turn the device off on take off and landing, but some airlines do now allow wifi to be on and offer in-flight service. They still require you to keep cellular and bluetooth off. Also, while I sometimes do take my laptop out of my bag on long flights, it's just cramped. Space is at a premium on a flight (hey, I fly economy...), you'll likely want to have a drink, people besides you may need to get up, spillage could occur if there is turbulence...

I don't really enjoy using my laptop on a flight, even though it's quite small. It's just so much trouble and not very comfortable.

However, I do love to watch saved movies, listen to music, and play games on a tablet. That tablet will most likely need to have radios turned off. My phone will typically just stay off and stowed far enough, since I don't really change SIM cards until I can do so safely without risking to lose the thing.

But then, one can also think of how you should avoid using transmitting equipment in a hospital. They have similar rules about radios as planes to avoid interfering with cardiac stimulators, MRI equipment, etc.

Having all kind of different applications handle each type of killswitches separately is quite risky and complicated. How are you certain that things have been turned off? How do you check in the UI whether it's the case? Can you see it quickly by scanning the screen?

What about the actual process of switching things off? Do you need to go through three different interfaces to toggle everything? What do you need to do if you don't have a physical switch to use?

What about persistence after a reboot?

urfkill is meant to, in time, address all such questions. At the moment, it still needs a lot of work though.

I've spent the last day fixing bugs I could find while testing urfkill on my laptop, as well as porting it to logind (still in progress). In time, we should be able to use it efficiently in Ubuntu to handle all the killswitches. With some more work, we will also be able to use it to manage the modem and other systems on Touch.

For the time being, urfkill is available in the archive, for those who want to start experimenting with it.