Making weston (or maybe libinput) ignore an input device

[Matt Hoosier]

Hi all,

The thing I'd like to arrange is for a device which is otherwise a
valid keyboard, not to get automatically vacuumed up into the Weston
DRM backend's usage of libinput.

Nowadays, Weston has delegated most of its former firsthand extraction
of UDev properties to libinput. Nothing exists (that I found) in
Weston's immediate sources to cause an input device reported through
the libinput UDev seats to be ignored. I also had a quick stroll
through libinput to look for some kind of sensitivity to a UDev
property with that effect, but didn't spot anything likely.

Is there a best way to do this? The best thing I could think of was to
try to add a late-running UDev rule that subtracts out the
ID_INPUT_KEYBOARD=1 property, so that libinput won't know what to do
with the device. But that seems like a fragile solution -- some
package unknown to me could come along and install an even-later
running rule that messages that arrangement up.

-Matt