Hi I have 2 KDE Neon installs on 2 different computers
They both have the same problem.
That is that sometimes the system becomes unresponsive

Switching to a TTY (i.e. Ctrl+F!) and running top shows xorg using high CPU
Some other symptoms are that keyboard key presses aren't working in my Plasma session at all, but work in the TTY

This issue can be caused by plugging in or removing a USB device or waking from suspend

My laptop is a KDE branded Slimbook V1
Desktop is a handbuilt machine

What is causing this?
How can I stop it?
Many thanks

Ok after some research, I think I have found out what was wrong.
Xorg problems are difficult to solve as they can be caused by so many things, and it's hard to Google "Xorg broken" and find a resolution!

When plugging in a new device, Xorg does indeed max out my CPU.
Also another program uses too much CPU as well when that happens - that program is kglobalaccel5

It seems like that program captures and handles all the shortcut keys in KDE, like alt-tab etc.
After doing some Googling I found:
https://unix.stackexchange.com/question ... ge-when-co
And the bug:
https://bugs.kde.org/show_bug.cgi?id=306352

It seems like a similar (or the same issue).
So I ran the following in a terminal:

Code: Select all

mv ~/.Xmodmap ~/.Xmodmap1 && echo 'keycode 104 = KP_Enter' > ~/.Xmodmap


Rebooted and that seems to fix my problem (and the "enter" key functions as "return" as before).

So it seems like the .Xmodmap file that comes with KDE Neon is horribly broken and causes a cascade of issues right up to effectively breaking the desktop when plugging in a USB device!

I think KDE software is very impressive, stylish, feature-full and fun however it is such a shame that big issues like this can get through.
I have had this issue for over a year and a half and have had to reboot my laptop several times while onsite with a client and been horribly embarrassed when that has happened.

Other people with the same bug please try above and see if this helps you too