full crash of host machine

[mMerlin]

This report is going to be very incomplete for now. I'll update it, if I can get some instruction on what and how to collect some better detail. I am getting this crash half a dozen times a day when working in the environment

Environment: Host Fedora 31 workstations 5.5.10-200.fc31.x86_64 dual monitors 16GB memory, 4 cores Guest Fedora 31 workstations 5.5.10-200.fc31.x86_64 single monitor 6GB memory, 2 cores Large window, slightly extending past the physical monitor size scaled mode Running guest application: qtcreator, debugging an application

The symptoms, just before the hard (black screen) crash of the host:

Attempt some operation in qtcreator, like clicking to create a new breakpoint. The application freezes, the VM freezes, and all other applications windows except shells freeze. Freeze might not be quite right. Clicking on an application window on the host (2nd monitor) that is occluding a shell window activates the shell not the application window. So the application might already be dead, and just a ghost of the window left on the desktop. The shell window seems active, but not much time to look around. In a few seconds, the host goes into full black screen crash, with a blinking text cursor. Sometimes, in a few more seconds, the host login windows appears without any additional user actions. Sometimes, ctrl+alt+del will initiate a reboot.

So, is there anything I can enable ahead of time, to get a log that might be useful for tracking this down? What data can I collect after host reboot to include here?

I have other fc31 guest vms that are not crashing, so there is some interaction with the running applications. But a misbehaving application should not crash the VM, and definitely should not crash the host machine.