Connection made but not able to steer mouse or use keyboard

[Chaoimin]

Hi there fellow NoMachine devs and users,

I’ve been having this issue now for a very long time (multiple years), and I’ve been trying to figure out what is going on. I regularly update NoMachine so I’m confident this is version independent. If there is any more input needed, like logs, please provide info on what and how to deliver.

I’m using Debian testing and the latest version of KDE plasma. The sessions used are running X11, not wayland (although I’ve used wayland for a while as a test and same problem)

This is the issue:

When connecting through nomachine on linux, a lot of times the mouse and keyboard aren’t working. I can see the desktop, I know the machine hasn’t frozen or crashed, because I’m connecting through SSH and I can get the display out of sleep mode using

DISPLAY=:0 xset dpms force on

or display letters on the screen and do input using

DISPLAY=:0 xdotool key Ctrl

To get a blank screen to show again, or for example

DISPLAY=:0 xdotool key a

to display the letter ‘a’.

When I use

/usr/NX/bin/nxserver –restart

to restart the service, nomachine cleanly restarts and I can connect again but the issue remains: no mouse or keyboard input.

To fix this, and it is the only fix that I have found on the forums and internet that works, nothing else yet: I have to restart SDDM. This means my open windows and applications have to be restarted. This is a nuisance.  So this seems to be somewhere inside KDE plasma.

I put this machine on standby every night, sometimes I totally turn it off and then back on again. This issue seems also independent of that, although when I turn it off and back on, it “feels” like the issue happens less often. It never happens when I connect using nomachine right after a clean reboot/when I turn the machine on.

Can someone please help me diagnose this issue with me? I’m a fairly seasoned Linux user, got the fedora and beard to prove it although it is not an Arch sized beard. It is however, Gentoo sized.

[Britgirl]

This seems to be related to your Linux host being headless, ie. without a monitor. You probably don’t have a monitor plugged in so, you should stop sddm and restart nxserver.

sudo services sddm stop

sudo /etc/NX/nxserver --restart

Then NoMachine will create its own virtual display. To avoid sddm restarting itself after a future reboot, disable it completely

sudo systemctl disable sddm

Information about headless hosts is available here: https://kb.nomachine.com/AR03P00973

[Chaoimin]

Hey Britgirl,

This is a laptop I use daily so it’s not headless. For further reference: sddm runs on boot. The laptop contains a cpu/gpu and a Nvidia GTX980 mobile dedicated graphics card. External monitor is plugged in on the hdmi output, laptop screen is also used so it’s a dual screen setup.

[Britgirl]

Please send us debug logs from the computer you are connecting to. You should enable debug and then reproduce the problem. You can extract them using the instructions here: https://kb.nomachine.com/DT07S00243

Send them to forum[at]nomachine[dot]com. Please use the title of this topic as the subject of your email. Thanks!

[Britgirl]

Could you try adding this to the node.cfg file?

DisplayAgentExtraOptions “-alteventapi 1”

Locate the node.cfg file, edit it by adding the above line, then save. Restart the server.

[Chaoimin]

Hi,

I’ve sent two mails, one today and yesterday explaining what I experienced.
I hope this will help with a diagnosis on the issue.
Enabling the option in node.cfg didn’t fix the issue unfortunately.

Please let me know if there is anything I can do to help.

[Bilbotine]

Hi Chaoimin,

Thank you for sending the logs; we checked them and they are clean, so unfortunately, the option we provided previously didn’t work.

Can you try this option instead: DisplayServerExtraOptions “-eventdelay 0” ? We are not sure it will resolve the issue, but let’s try anyway.

We would also like to know the output of this command:

DISPLAY=:0 xinput list –long

Thanks!

[Chaoimin]

So one thing I’m wondering about is what is the difference between a “/usr/NX/bin/nxserver --restart” and restarting SDDM, from nomachines perspective. I’d expect restarting the service would fix the issue after sleep state but it doesn’t, a SDDM restart does. So there is some part of nomachine that is stale and not affected by the nxserver restart. If I could get to that I could write a wrapper that executes after sleep and restart that specific part.

Is there a list somewhere with all the options like ‘DisplayServerExtraOptions “-eventdelay 0” ‘ I can try?

The output is from when I restarted SDDM, I’ll check again if the issue arises and see if any input device is missing. I wouldn’t know how to get it back after sleep without restarting SDDM though.

Output of DISPLAY=:0 xinput list –long :

~$ DISPLAY=:0 xinput list –long
⎡ Virtual core pointer                        id=2    [master pointer  (3)]
Reporting 3 classes:
Class originated from: 4. Type: XIButtonClass
Buttons supported: 10
Button labels: “Button Left” “Button Middle” “Button Right” “Button Wheel Up” “Button Wheel Down” “Button Horiz Wheel Left” “Button Horiz Wheel Right” None None None
Button state:
Class originated from: 4. Type: XIValuatorClass
Detail for Valuator 0:
Label: Rel X
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 4. Type: XIValuatorClass
Detail for Valuator 1:
Label: Rel Y
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative

⎜   ↳ Virtual core XTEST pointer                  id=4    [slave  pointer  (2)]
Reporting 3 classes:
Class originated from: 4. Type: XIButtonClass
Buttons supported: 10
Button labels: “Button Left” “Button Middle” “Button Right” “Button Wheel Up” “Button Wheel Down” “Button Horiz Wheel Left” “Button Horiz Wheel Right” None None None
Button state:
Class originated from: 4. Type: XIValuatorClass
Detail for Valuator 0:
Label: Rel X
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 4. Type: XIValuatorClass
Detail for Valuator 1:
Label: Rel Y
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative

⎜   ↳ SynPS/2 Synaptics TouchPad                  id=16    [slave  pointer  (2)]
Reporting 7 classes:
Class originated from: 16. Type: XIButtonClass
Buttons supported: 7
Button labels: “Button Left” “Button Middle” “Button Right” “Button Wheel Up” “Button Wheel Down” “Button Horiz Wheel Left” “Button Horiz Wheel Right”
Button state:
Class originated from: 16. Type: XIValuatorClass
Detail for Valuator 0:
Label: Rel X
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 16. Type: XIValuatorClass
Detail for Valuator 1:
Label: Rel Y
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 16. Type: XIValuatorClass
Detail for Valuator 2:
Label: Rel Horiz Scroll
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 16. Type: XIValuatorClass
Detail for Valuator 3:
Label: Rel Vert Scroll
Range: -1.000000 – -1.000000
Resolution: 0 units/m
Mode: relative
Class originated from: 16. Type: XIScrollClass
Scroll info for Valuator 2
type: 2 (horizontal)
increment: 120.000000
flags: 0x0
Class originated from: 16. Type: XIScrollClass
Scroll info for Valuator 3
type: 1 (vertical)
increment: 120.000000
flags: 0x0

⎣ Virtual core keyboard                       id=3    [master keyboard (2)]
Reporting 1 classes:
Class originated from: 5. Type: XIKeyClass
Keycodes supported: 248

↳ Virtual core XTEST keyboard                 id=5    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 5. Type: XIKeyClass
Keycodes supported: 248

↳ Power Button                                id=6    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 6. Type: XIKeyClass
Keycodes supported: 248

↳ Video Bus                                   id=7    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 7. Type: XIKeyClass
Keycodes supported: 248

↳ Video Bus                                   id=8    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 8. Type: XIKeyClass
Keycodes supported: 248

↳ Power Button                                id=9    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 9. Type: XIKeyClass
Keycodes supported: 248

↳ Sleep Button                                id=10    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 10. Type: XIKeyClass
Keycodes supported: 248

↳ AT Translated Set 2 keyboard                id=15    [slave  keyboard (3)]
Reporting 1 classes:
Class originated from: 15. Type: XIKeyClass
Keycodes supported: 248

[fra81]

Hi Chaoimin,

I don’t have an explanation why restarting SDDM helps and restarting the NoMachine server doesn’t, since the nature of the problem is not clear yet, and we’re still unable to reproduce it on our labs. This could also indicate an issue in KDE Plasma rather than NoMachine.

Can you please try to press a key on the physical keyboard of the laptop you use as a server when you reproduce the issue, and check if input events through the NoMachine session start working from that moment on?

Did you restart the NoMachine server (/usr/NX/bin/nxserver --restart) after adding the DisplayServerExtraOptions “-eventdelay 0” option in the node.cfg file? Would you try again if you didn’t?

Is there any screen lock app running on the server when the issue is being reproduced?

[Author]

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