Fedora 31 guests suddenly slow or hang or go to a black screen or kernel panic

[soldack]

I have been using Virtual box 6.1.4 without issue on a Windows 10 64-bit host with 32 GB RAM, AMD Ryzen 7 3800X 8-core 16 thread system, Nvidia GeForce RTX 2070 SUPER. I was running Fedora 31 Mate Spin in 16 GB of RAM with 8 cores presented. Today I found the system unable to start properly. The boot process would flicker on and off. I tried upgrading to Version 6.1.6 r137129 (Qt5.6.2) and it didn't help. I tried various things and even if I was able to boot, everything was very slow. Running date and sleep 1 in a loop showed as much as 8 second gaps.

I decided to just try booting the install iso again. This hung on startup. I have attached those logs. The settings are mostly defaults including 16 GB ram, VT-x/AMD-V, Nested Paging, KVM Paravirtualization. Video is 16 MB VMSVGA, 3D Acceleration disabled. It was set to use a VDI file with 100 GB of space. Audio was enabled, network was set for NAT, Intel Pro/1000MG.

[scottgus1]

Your log contains these lines:

{timestamp} HM: HMR3Init: Attempting fall back to NEM: AMD-V is not available
{timestamp} NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

You might notice in the guest window's Status Bar the green turtle: The choice of animal is appropriate: Your guest is running, just really slow. This is because a service that uses Microsoft Hyper-V is running on your host PC. Normally Hyper-V blocks Virtualbox. But your PC is of the type and OS where Virtualbox can attempt to run the guest using the Hyper-V engine. This arrangement is still being developed and isn't 100% yet.

If VirtualBox is running without Hyper-V enabled, and nothing else is interfering with hardware virtualization (VT-x / AMD-V), then the usual virtualization icon () will be seen in the Status Bar.

To turn Hyper-V off completely, do this:

1. Shut down all programs. You will have to reboot your host.

2. Look into the 64-bits tutorial, 2nd post, points 2 & 3 and ensure that none of these things are running.

3. Find the Command Prompt icon, right click it and choose Run As Administrator.

4. Enter this command:

bcdedit /set hypervisorlaunchtype off

5. Enter this command:

shutdown -s -t 2

6. When the computer turns off, unplug it for 20 seconds. Then plug it in again and boot up Windows 10.

Your Virtualbox should be running now. If the green turtle still appears and the tell-tale lines are in the log, try all the steps again. If you don't get the standard virtualization icon, post back exactly what you did and we'll try to help some more.

For further info, see I have a 64bit host, but can't install 64bit guests and https://www.tenforums.com/tutorials/139 ... puter.html

[soldack]

Thanks. I made those changes and things seem better but I still see odd delays. For example, running a simple script like this:
while [ 1 ]; do date; sleep 1; done

shows 2-4 second gaps at sometimes.

I attached logs from my full installation running. This has 3d acceleration on but not much else different from the live cd test.

[soldack]

Installing the virtualbox extensions seems to have fixed the random pauses. Thanks!

[scottgus1]

Thanks for the info. If by the 'extensions' you meant Guest Additions (there's an Extension Pack that can go on the host too) your guest had GAs 6.0.0, which was probably too out-of-date for Virtualbox 6.1.x.

Glad your guest is running smoothly!