Video goes black on full screen view and never recovers

[mrzenwiz]

I run VB 6.1.14 r140239 (Qt5.12. on Xubuntu 20.04.1.

I recently installed a Linux Mint 20 VM and an Ubuntu 20.04 VM and both of them are showing this odd behavior.

After I've installed the guest additioins, I reboot the VM and set the View to Full Screen. The screen goes black and nver shows anything else. I can't even cause it to reboot, I have to exit the VM window with the Power Off option. Sometimes, two or three reboots later, I get a display again, but never in full screen mode, and that always kills the VM.

The Mint VM tells me I don't have hardware acceleration enabled, and I tried turning on 3D Acceleration, but it makes no difference.

Both VMs are using the VMSVGA driver for the display. Is there another one that works properly?

What am I doing wrong?

Thanks.

[The Raven]

Guest Additions has been broken for my linux guests since 6.1.6 - I'm still using the 6.1.4 GA's which work fine.
There have been tickets opened for various problems with GA's, some have been fixed but not all, including fullscreen
with VMSVGA and various re-size errors.

Current open tickets include
https://www.virtualbox.org/ticket/19640
https://www.virtualbox.org/ticket/19496

[mrzenwiz]

I found a workaround that seems to handle the problem.

Those two VMs had only 16Mb of video memory assigned. When I increased that to 32Mb, the problem went away.

It's kludgy, but it works.

Thanks.