Re: A modest proposal...

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

On Wed, Jun 27, 2001 at 09:52:46AM -0700, James Simmons wrote:
> 
> > > Howdy.
> > > 
> > > I notice that, at present, several of the handlers (such as evdev)
> > > assign device numbers independantly. Hence, /dev/input/event2 and
> > > /dev/input/mouse2 may not refer to the same device, and (similarly)
> > > may not refer to the device dubbed input2 on initialization.
> > > 
> > > Might it not make for a somewhat more user-friendly world to have
> > > handlers use dev->number for determining the minor number for each
> > > connected device?
> > > 
> > > This would also make a table of connected input devices somewhat more
> > > useful.
> > 
> > Sounds reasonable to start searching for free numbers at the dev->number
> > position. What others think?
> 
>    Is it possible to match them up like that? I was thinking about it and
> to me it seems like a huge task. Unless I miss understood what he
> suggested.

We can't match them completely, but we should be able to make a good
approximation if the user doesn't do too nasty things to the system.

>    One thing I like to bring up about numbering is when you plug and
> unplug devices. At present when you unplug a device and plug it back in
> the device becomes /dev/input/event[n+1]. Where /dev/input/event[n] now
> has no device attached.

Only if it is open. If it is not, it'll become /dev/input/event[n]

> There is a limit to 256 event devices. Now you
> say that is a good number but given 5 input devices it whould take 15
> times unplugging and plugging them back in before you run out of numbers.
> So I like to suggest that we keep track of the "free" numbers and grab the
> lowest one.

We do this, at least in evdev.

> Say you have 5 devices and you unplug device 3 and then plug
> it back it then it should be device 3 again. Not device 6. 

-- 
Vojtech Pavlik
SuSE Labs