Messages in this thread | | | Date | Thu, 22 May 2008 17:51:53 -0300 | From | Henrique de Moraes Holschuh <> | Subject | Re: [PATCH 14/15] rfkill: do not allow userspace to override ALL RADIOS OFF |
| |
On Tue, 20 May 2008, Ivo van Doorn wrote: > On Sunday 18 May 2008, Henrique de Moraes Holschuh wrote: > > SW_RFKILL_ALL is the "emergency power-off all radios" input event. It must > > be handled, and must always do the same thing as far as the rfkill system > > is concerned: all transmitters are to go *immediately* offline. > > I don't quite agree here. The SW_RFKILL_ALL key is the one send by thinkpad-acpi, > what makes that key so special that is has to be handled differently then a key > that only controls a single radio type?
Well, first there is no KEY involved, it is a SWITCH :-) But that's not the reason it is special.
What makes SW_RFKILL_ALL special, is that it is the kernel view of *The* RFKill Switch. SW_RFKILL_ALL is the event you get when the user manipulates the very *thing* that created the "rfkill switch" term.
You get that event when someone moves that slider switch in the side/top of a laptop which has to kill all RF output in hardware as far as safety regulations go. Therefore, it refers to the only rfkill switch that has guidelines that say that it must always work, and that it must not be possible to override it in software.
Too bad that doesn't apply to "removable" radio transmitters, like PCMCIA and ExpressCard WLAN cards, USB RF transmitters, and so on... probably, the user is expected to yank them off when he moves the switch to the "no radios working here!" position. Well, we can do better. We can make it apply to these other radio transmitters, too.
So yes, it *is* special when it is doing its "power DOWN the transmitters" function. It is not special at all when it is in the "allow radios to function if they want to" position, which is why I special-cased only the "OFF" state.
IMHO, that makes it special enough to implement it in a different way that is not subject to, e.g., brain damage in userspace.
As for thinkpad-acpi being the only in-tree code issuing that event so far, well... I have seen laptops from many vendors with that switch, and it is likely that the firmware of at least some of these laptops let you know the state of the switch (like the thinkpad firmware does), so I'd expect more users of SW_RFKILL_ALL to show up soon. I am just paving the way.
That, and as an user, I'd really like to be able to implement a KEY_RFKILL_ALL keycode to use when I don't have a proper SW_RFKILL_ALL in my laptop. But one thing at a time. Small steps.
> All keys should have the same rules when it is pressed, so either all keys should > force the change, or none of them should.
IMO, "kill ALL radios" events are is the only kind of rfkill input event that have to *always work*, even if something in userspace tried to configure it not to.
-- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh
| |