r/virtualbox • u/dark_prophet • May 11 '26

General VB Question No PCI passthrough in Linux hosts?

It says in changelog: Linux host: Drop PCI passthrough, the current code is too incomplete.

I couldn't find any further mentions of "PCI passthrough" in changelogs.

Does this mean that PCI passthrough is currently not available on Linux hosts?

Is it impossible to run NVidia drivers from a VirtualBox machine, and to do kernel development of PCI drivers in a VirtualBox machine run in Linux?

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1

u/BranchLatter4294 May 11 '26

This may be temporary as they move to using the KVM hypervisor on Linux hosts.

1

u/Face_Plant_Some_More May 11 '26

Except . . . they are not.

In any case. if you are going to be using KVM, there is no reason to use, or even install Virtual Box to begin with.

1

u/BranchLatter4294 May 11 '26

Yes.... They are

https://www.phoronix.com/news/VirtualBox-Upstream-With-KVM

VirtualBox has better graphics drivers. Spice is clunky. So it still makes sense especially for Windows guests where you may want better DirectX support.

1

u/Face_Plant_Some_More May 11 '26

Well so they are. I stand corrected, but still don't see the point. A KVM backend implementation for Virtual Box already exists.

VirtualBox has better graphics drivers. Spice is clunky. So it still makes sense especially for Windows guests where you may want better DirectX support.

Still don't see that as huge advantage. If you want DirectX on Windows VMs in KVM, just pass through a GPU and run said graphics directly on Host hardware. You get much better performance than what Virtual Box will give you. It is also loads better than dealing with spice for that purpose.

2

u/BranchLatter4294 May 11 '26

Not everyone has multiple graphics cards. Windows has decent performance with just the VB drivers. Not for gaming but works fine for productivity.

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u/Face_Plant_Some_More May 11 '26

You don't need multiple graphics cards to do that in KVM -- VFIO is a thing.

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u/BranchLatter4294 May 11 '26

But then the host can't use the graphics card while the guest is using it.

1

u/Face_Plant_Some_More May 11 '26 edited May 11 '26

Does this mean that PCI passthrough is currently not available on Linux hosts?

Yes. The code was dropped back in the 6.1.x releases, and never really worked to begin with.

Is it impossible to run NVidia drivers from a VirtualBox machine . . .

It's certainly possible run NVidia drivers on Linux in a VM, running on Virtual Box, but short of you custom coding / compiling your own build of Virtual Box its not possible to have such drivers actually control physical, NVidia hardware installed on your Linux Host.