evdev keyboard problem in xorg 1.5.2 and evdev 2.0.99+

Peter Hutterer peter.hutterer at who-t.net
Wed Dec 31 20:00:34 PST 2008

On Wed, Dec 31, 2008 at 02:19:51PM -0700, Scott Serr wrote:
> Timo, it almost works.
> I installed a fresh Ubuntu 8.10 with xkb-data package
> xkb-data_1.3-2ubuntu4.4_all.deb.  All updates to date.  Indeed there is
> an evdev config file in the xkb-data.
> This is very weird... The only way it works is if I switch Preferences->
> Appearance-> VisualEffects back and forth between None and
> Normal/Extra.  It doesn't matter if it is set one way or the other...
> The "up arrow" causing a "PrtScn" happens every time before this is
> toggled.   And after a toggle, "up arrow" works correctly.  I also
> tested on a new user, same behavior.  Need to fiddle with the
> VisualEffects radio button.

printscreen is handled through a passive grab on the keycode. evdev has
different keycodes than the kbd driver, with the up/printscreen overlap being
the most prominent.

when you hit a key on the physical keyboard, this keyboard's (evdev) map is
flushed into the core keyboard and the keycode-keysym mapping in the core
keyboard change. however, if the clients don't update the map after that they
listen to the wrong keycodes leading to the symptoms you described.
restarting the client causes said client to load the keymap from the core
keyboard (i.e. the evdev one now) and have the right layout from the start.

This bug has a zombie-like ability to come back and annoy users, though it has
been "fixed" in many different ways many times already.


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