Since VBox 6.1, there is now simply no way to have “3D acceleration enabled and working”. That’s the problem.
So it’s an easy test: tick 3D Acceleration for workstation with VMSVGA, and the result we want is for Debian to boot all the way into the system. That’s how we know it is working.
To actually see the difference 3D Acceleration makes, you could test in vbox 6.0 or earlier by comparing “3D Acceleration” ticked or unticked with the setting on VBoxVGA. Inside Workstation, find a 1080p video with a high frame rate like 60fps, e.g.
video.mp4 from this github. Then, play the MP4 in
sudo apt install mpv) which is a video player that has hardware decoding enabled by default.
On my hardware, the difference is colossal. GPU accel pass-through is needed for normal smooth video playback unless you have an extremely fast CPU which doesn’t apply to most of us. GPU acceleration exists for a reason.
No guarantee this test would work on your hardware, but for most graphics chips this should be replicable.
A lot of reasons why I can’t do that.
Because I’ve already tested stock Debian 10.2 guest which works with 3d accel, I’m sure they’d say ‘Go back to Patrick because he’s modified Debian in some way, it clearly isn’t the fault of virtualbox.’ I have also tested other Debian-based VMs in the same vbox - Ubuntu, Mint, Xubuntu - and all of them work.
Sure I’ll try that out. Will continue working on this, and I agree I can also ask on vbox forums as part of that.
Another possible clue:
With Gateway set to 256MB RAM, VMSVGA 3D accel WORKS, i.e. Debian fully boots. But not if 768MB / graphical mode.
Could the RAM-adjusted graphics code have something to do with this - if the mod is not contained in stock Debian?
Another possible clue:
I now have an error
update-initramfs: failed for /boot/initrd.img-4.19.0-6-amd64 with every
apt upgrade now. (Update: doing
sudo dpkg --configure -a gets rid of this symptom though.)
Can’t find the link right now but a week ago I found vbox forums thread discussing an idea where the guest kernel needs to reconfigure each time you change from VBoxVGA to VMSVGA, etc? So it may be related?
Can you try in vbox 6.1 changing a workstation to VMSVGA and see if it produces this same symptom?
Update: no, kernel headers in whonix have nothing to do with the problem. I uninstalled & reinstalled headers in workstation, combined with reinstalling guest additions 6.1.0 inside it, and 3D accel still doesn’t work in any of those combinations of things.