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Re: Video and Keymap Quirks

On Thu, 2007-07-12 at 16:59 -0500, Michael E Brown wrote:
> On Thu, Jul 12, 2007 at 09:20:56PM +0100, Richard Hughes wrote:
> > On Thu, 2007-07-12 at 13:00 -0500, Michael E Brown wrote:
> > > I havent had a lot of time to pursue it, but I have seen several people
> > > working on things to handle killswitches. The problem I've seen is that
> > > several of them dont take into account features that the Dell notebooks
> > > have: software configurable killswitches, and killswitch for cellular in
> > > particular. 
> > 
> > Why do we need to configure a killswitch? Surely a kill switch is just
> > something that kills _all_ wireless for aircraft. If you want to power
> > down individual devices surely this should be done in sysfs.
> The word "surely" implies policy.

No the work surely was intended to mean "it should".

> The dell implementation provides
> mechanism, the user provides policy. Aircraft is one policy.
> I'm-sitting-at-starbucks-and-dont-want-somebody-to-hack-my-wireless-
> while-I-upload-pictures-from-my-phone-to-my-laptop-over-bluetooth
> is another policy.

Then you don't use a kill switch, you just don't set your bluetooth
adapter to discoverable. Bluetooth adapters use lots of power - the
device should be powered down when not in use and only powered up when
needed. But that's not my point.

> The user can decide which policy they want the
> killswitch to provide via either BIOS configuration options or through
> dellWirelessCtl.

It seems to me the default action should be kill _everything_ and only
lets really advanced users who know what thay are doing can use

> Writing software that just assumes that the killswitch can only ever do
> an all-or-nothing operation is encoding bad policy in our software.

I disagree. Getting on a plane and switching the kill switch to off,
only to find it's only disabled the bluetooth and not the wlan is a
totally bad design decision in my opinion.

> Also, sysfs, as I've mentioned elsewhere, is a crappy interface for this
> specific functionality. dellWirelessCtl is implemented in userspace, and
> it doesnt make sense to try to write a kernel module to do it. 

Unfortunately I think Dell hardware is the odd-one-out here - in all the
hardware I've used the kill switch is either implemented in hardware or
involves writing low level commands or poking values in registers, and
hence handled in kernel drivers.


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