xorg: Fixing xmodmap persistence issues on USB replug
There is a long-standing bug in x.org that loads the default
xmodmap configuration when an USB keyboard (or mouse?) is
unplugged and replugged. This wipes out any changes
to the keymap configuration done via xmodmap.
While ordinary user will rarely be affected, users of KVM
switches will see their keymap changes wipes on every device switch.
Will there be a patch?
As far as I could determine, this is a lomg0term known issue
and the x.org maintainers do not plan to fix it due to ressource
I habe unsuccessfully tried a lot of things. I finally have found
a solution that actually works, but is so inelegant that I had some
real trouble bringing myself to use it.
The fix I found is to reload the xmodmap
changes every second.
I can only call this a dirty hack and would like to stress that
something like this is never a good idea, will probably cause
secondary problems and should generally be avoided.
Having said that, it seems to work pretty well.
My local xmodmap changes are in the file $HOME/.xmodmap.
I have written a small demon that gets started with the window
manager (other ways should work too) and calls
system("xmodmap - < /home/wagner/.xmodmap")
once a second in a loop. This does not seem to create
any noticeable system load and so far I have not noticed
any problems with
keyboard input or mouse movements. If your set-up can switch
faster than 1 second (my KVM + monitor combination cannot),
you may want to run this more frequently, e.g. every 500ms.
Obviously other calls to xmodmap can be used as well.
There are different ways to do demons. Here are some.
Obviously you can use whatever you prefer.
Last update: 2023 Arno