How To debug evdev

[Peter Hutterer]

On Sat, May 22, 2010 at 08:30:38PM +0200, Philipp Hagemeister wrote:
> Hi xorg list,
> 
> my currently running X.org (1.7.7, from debian unstable) does not
> recognize USB input devices anymore. The devices show up in /dev and in
> a second X instance.
> 
> However, I'd like to solve the problem once and for all and not lose my
> preciously configured X session. I assume the problem is in the evdev
> module as new devices do not show up in /var/log/Xorg.0.log as they
> usually do.
> 
> So, how do I debug evdev? Is there a suitable way I can access X
> internals of a running session or restart evdev, but not X?

evdev is a module loaded by the server at runtime, so you can't restart
evdev without restarting X. To debug, you need to attach gdb to the running
server or start through gdb. see also:
http://wiki.x.org/wiki/Development/Documentation/ServerDebugging

in your case, if evdev isn't loaded for a device for some reason that's
usally a issue with the backend or backend configuration (hal, for 1.7).
make sure input.x11_driver is set to evdev for all devices. If not, make
sure the hal config is all there (reinstall the package if needed, it's
named x11_input.fdi or something similar, IIRC).

Cheers,
  Peter