Input device design (3)

Waldo Bastian Waldo.Bastian at
Fri Sep 2 06:17:02 PDT 2005

On Wednesday 31 August 2005 19:16, Jim Gettys wrote:
> On Wed, 2005-08-31 at 02:56 -0400, James Cloos wrote:
> > BTW, just to be clear, I (at least) wasn't thinking of having the
> > actual i/o events go through this os-dependant, external server,
> > but rather just the initial discovery and hotplugging of i/o devices.
> >
> > I was expecting the external server to notify the X server of the
> > locations of the devices.  Ie, on Linux it could tell the X server
> > that /dev/input/event5 just appeared, is a pointer, and should join
> > the set of core pointers.  Or that eg /dev/input/event2 went away
> > and should be close(2)ed.  Et cetera.
> Exactly, though I think the X server can find out itself when devices go
> away: it will get an error on the file descriptor, so it isn't clear a
> close message is needed (unless we want to be able to take away a device
> already assigned to the X server...  Hmmm...)
> Do people think we need to be able to retrieve input devices once
> assigned to the X server.

For completeness I would add it.

A more interesting problem is how such disappearing devices should be handled 
at the X Client side. Should they removed from XListInputDevices? (I think 
so) What about X clients that have the device open with XOpenDevice? Should 
device ID's be reused?

Linux Client Architect - Channel Software Operation - Intel Corporation

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