Strange video behavior in VB

[Liam Proven]

On Tue, 27 Oct 2020 at 01:31, MR ZenWiz <mrzenwiz at gmail.com> wrote:
>
> I'm not sure where to post this, but I thought I;d try here first.
>
> I just installed Linux Mint 20 in a VB VM on my Xubuntu 20.04.1
> desktop,

You mean VirtualBox, right? I ask 'cause "VB" is the standard
abbreviation for MS Visual Basic and from the title that's what I
thought you meant, and I was at a loss as to what this meant on or re
Linux until I read the message.

Standalone version from www.virtualbox.org (current = 6.1.14) or the
older version from the Ubuntu repos? (Not sure, can't check as I am
typing on macOS.)

> and it seems to work more or less well - until I tell it to
> go into full screen mode.  The video goes all black and this persists
> through one or two reboots before it clears up.  I can't use the full
> screen mode at all.

Reboots of the host or of the guest?

> I do get a warning that I don't have hardware acceleration enabled for
> lack of a driver, but the drier search turned up nothing - not really
> a surprise since the VB video driver isn't really hardware.

The guest doesn't know that. It just sees a graphics card. You can
pick which one under:

 VBox -> VM Settings ->  Display -> Graphics controller

The choices are:
• VBoxVGA
• VBoxSVGA (the native one)
• VMSVGA (compatible with VMware, I believe)
• None

> I have the guest additions installed,

Those *contain* graphics drivers. So you *do* have graphics drivers installed.

How did you install them? From the VBox ISO (latest but you don't get
updates) or from the Ubuntu repos in the guest?

> and I can resize the
> screen/window, but in full screen mode, it goes blank and does not
> appear to recover.
>
> Any clues?

We need more info.

To enable hardware passthrough, you need to do 2 primary things:

[1] Enable 3D acceleration in that VM in VBox's  Display Settings
[2] Install graphics drivers via the Guest Additions, either the ones
VBox provides in an ISO or via those in most Linux distros' repos.

I described it in a blog post here:

https://liam-on-linux.livejournal.com/33987.html

Notes:
• To do much with them, you need a 3D-accelerated desktop (e.g. GNOME
3, Cinnamon, Unity) or to enable it under one of the desktops where
it's optional (Maté, XFCE etc.)
• I have had significant problems with every version of KDE I've tried
• To build the kernel module, you need compilers etc install. I
recommend installing the packages `build-essential` and `dkms` and the
headers for your current kernel *before* you install the extensions.
If you did not have this, remove the extensions, reboot, install DKMS,
the kernel headers and the build essentials, reboot, install the guest
additions, shut down the VM, enable 3D acceleration in VBox settings,
and restart the VM.



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