Multi-GPU / DisplayLink and 3D acceleration

[starlocke]

I have a particular system. It is equipped with a USB-3.0-to-DVI device by Startech that enables an extra monitor to be used ( ​http://goo.gl/4xOZbJ ). This is because a Mac Mini has only 1x HDMI and 1x Thunderbolt/MiniDisplayPort available and no room for "traditional" expansions under 100$ - the super geeked out expansion would be to plug a generic Nvidia video card into a Thunderbolt-PCI-X unit that costs a small fortune.

When I have my USB-DVI adapter plugged in, VirtualBox apparently runs a test in the VM Configuration Window (ie: start VBox, select a VM, click "configure") and concludes that the host system does not support 3D acceleration. Also, when I try to start the VM, VBox will quit claiming that apparent lack of 3D support.

However, when I remove the USB-DVI adapter, everything is peachy and works as expected. I can even start a 3D-accelerated VM without the USB-DVI adapter, then plug it in, and, everything still works. The only downside is that I wouldn't be able to start the VM with 3 monitors set up.

I wondered if it was possible to enhance the test so that detecting any 3D-capable driver will result in a PASS instead of a FAIL, and, to offer an option to configure the graphics drivers being used by VBox to launch VMs. For example, I'd like to be able to configure VBox to always choose the Intel HD Graphics 4000 for the 3D acceleration. Also, does it make sense to choose more than 1 graphics driver/adapter to handle the 3D acceleration? If so, we should be able to choose multiple.

[starlocke]

I forgot to mention in the original description... the USB-DVI adapter needs with its own drivers, and, I believe that they act like a second video card. The name "DisplayLink" comes up in the adapter's USB information profile.

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.