Re: 'Phys:' field for keyboards (and other input devices)

[Vojtech P. <vo...@su...>]

On Fri, Sep 27, 2002 at 08:54:25PM +1000, Brad Hards wrote:
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> On Fri, 27 Sep 2002 19:10, Vojtech Pavlik wrote:
> > There is a way to determine what event0 is (EVIOCGPHYS), or to find out
> > what a certain mouse has become (/proc/bus/input/devices).
> >
> > As to the device number assignment, it's not sanely possible to do with
> > hotplug, etc. The minor numbers will simply have to stay more or less
> > random.
> Is EVIOCGPHYS unique?

Yes. No two devices in the system can have the same phys: entry

> If not, when wouldn't it be better to use EVIOCGUNIQ instead?
> If so, then what is EVIOCGUNIQ for?

It's an identifier that a device may or may not have, and if there is
one, it must be universally (*) unique for this devices bus, vendor and
device id. Like USB storage UUID. It may be a serial number. Not that
many input devices have it, but the possibility is there.

(*) - in whole universe, not just the system. Also it must not ever change.

-- 
Vojtech Pavlik
SuSE Labs