QubesOS 4.2 freezes (using KVM switch)

Hi there,

I did a fresh (default) installation of QubesOS R4.2.0 on a HPE Z240 (latest BIOS) with Intel Xeon E3-1240v5, 32GB RAM, NVidia Quadro K620 graphics card. Memtest was executed for several days without problems.

I am using a KVM switch (USB and graphics card connection) to switch between 2 computers.

I have the problem that QubesOS freezes after some time. I am working on the other computer and when switching back to QubesOS xfce is freezed. But: I am still able to move the mouse and see the mouse pointer moving. I am unable to click on any window or to enter text.

I am also able to login to cli by pressing Ctrl+Alt+F4. Changing back with Ctrl+Alt+F1 does not change anything.

I did another install and disabled “Use a qube to hold all USB controllers” (sys-usb) - this didn’t change anything, freeze is still there.

I checked the logs in /var/log/xen/console and /var/log/Xorg.0.log, but did not find any cause for the freeze.

Is there anything more I can do/check to find the cause for the freeze?

Best regards,

Are you able to login in TTY and execute the commands there?

Hi apparatus,

yes, exactly. When pressing Ctrl+Alt+F4 I am able to login with the user account. I am able to execute commands there (e.g. checking the logs with less).

So the system is not totally freezed. Mouse pointer is moving, Ctrl+Alt+F4 is working. But the gui (xfce?) is not working as it should.

Best regards,

Maybe it’s just a bug with screensaver?
Try to enter the password and hit Enter in the frozen xfce.


Ah, excellent hint! You are right, after entering the password and hitting enter, xfce is operable again.

Very strange behaviour indeed.

Best regards,

Possibly a problem with resume from suspend.

Have you tried increasing the sys-usb VM memory? I think increasing the memory fixed this issue for me.

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