No keyboard or mouse under X - How to debug udev?

[Mike Fleetwood]

Hi,

Quick background:
I have Fedora 12 installation recently transferred to new hardware
with embedded ATI Radeon HD 4250 GPU.  The ATI/Radeon X11 driver
didn't support the GPU and the VESA X11 driver just switched the
monitor into power saving mode.  Upgraded just X11 (and udev and
kernel dependencies) to versions from Fedora 13.  ATI/Radeon X11
driver now works and my desktop is displayed but X11 finds no keyboard
or mouse.

Worked around this by adding the following to /etc/X11/xorg.conf, to
tell X11 not to rely on udev to provide keyboard and mouse details.
Section "ServerFlags"

        Option "AutoAddDevices" "off"

EndSection


Question:
How do I investigate udev to see why X11 isn't getting a keyboard and mouse?

Thanks,
Mike