Do you have experience with VirtualBox in Debian 13 trixie?

[Manuel_Jordan]

Hello Friends

Do you have experience with VirtualBox in Debian 13 trixie?

There is the intention to install Debian 13 trixie in a laptop Lenovo and is need it use VirtualBox too
But there is a situation with a kind of conflict with KVM due a kernel upgrade.
I am not sure if this situation is already solved or not

Thanks in advance for your experience

[daniel.m.tripp (Dan Tripp)]

Isn’t there already another thread you started about clashing between VirtualBox and KVM? Why not just update the original thread / subject you started instead of starting a new one?

Wasn’t it solved? I’m sure there was an answer to your issue from @kovacslt :

VirtualBox 7.1.14: VirtualBox can't operate in VMX root mode. Please disable the KVM kernel extension

This was also linked in the VirtualBox 7.2.2 change log as one of the issues fixed. I thought I would add it here. Seems to be an on again off again problem dealing with kernel versions and VirtualBox versions. I found the information in this issue thread helpful and informative. VirtualBox Issues with KVM

@kovacslt

Moving from Debian 12 to 13 I faced the same problem.
My readings told me it’s because the newer kernel loads and inits kvm module by default, whereas the previous version did not. This makes impossible for Virtualbox to init virtualization on its own, so the sulotion is either to disable kvm initialization in GRUB adding a kernel parameter ( kvm.enable_virt_at_load=0 ) , or blacklist kvm module via /etc/modprobe.d/something.conf.
I choosed the latter, this what how it looks now on my computers:

cat /etc/modprobe.d/kvm-blacklist.conf 
blacklist kvm_intel

Adding that, and rebooting made Virtualbox working flawlessly.
As for version, I have now Virtualbox 7.2, is there a reason you are still trying 7.1?

The answer to your question on Ubuntu 24.04x should be exactly the same for Debian 13…

[Manuel_Jordan]

Hello Dan

About the mentioned link

• The title is generic but the post is in the “Ubuntu” category
• Is correct about the other reply about Debian according with experience by László

But I created this post for Debian users (in the “Other Distributions” category) in case if they do not arrive to the other link.

[easyt50 (Howard)]

Doing a quick search with Al, I came up with this. Hope this helps.
" the conflict between VirtualBox and KVM on Debian 13 (Trixie) is not fully solved upstream, but there are workarounds that people are using successfully." Co-pilot.

[Manuel_Jordan]

Hello Horward

Thanks for the feedback!

[sly]

Hi,

I was stuck with the same problem on debian 13 with a Rizen processor. I tried to blacklist kvm_intel as mentionned above, but after a reboot, I had the same problem because the kvm_amd module was loaded.

I wasn’t aware of kvm module amd/intel subtleties. And since I want this hack to work when my cpu is intel or amd, I went for :
# cat /etc/modprobe.d/blacklist-kvm.conf
blacklist kvm_intel
blacklist kvm
blacklist kvm_amd

And that did the trick. I don’t know if such blacklist should be included in the virtualbox debian package, but that would save people searching the web for answers

[easyt50 (Howard)]

Welcome to the forum @sly.
And ‘Thank you’ for your contributing your experience.

Have a nice day.

[Manuel_Jordan]

@sly

I wasn’t aware of kvm module amd/intel subtleties. And since I want this hack to work when my cpu is intel or amd, I went for :
# cat /etc/modprobe.d/blacklist-kvm.conf
blacklist kvm_intel
blacklist kvm
blacklist kvm_amd

Huge thanks for that important feedback!

[nevj (Neville Jackson)]

@sly

I don’t know if such blacklist should be included in the virtualbox debian package,

@Manuel_Jordan
If you apply that blacklist, other apps that require KVM ( eg qemu) will stop working.
It is not acceptable for virtualbox to require a blacklist that stops other apps working.
It certainly should not be included in any package.

[daniel.m.tripp (Dan Tripp)]

@nevj

It is not acceptable for virtualbox to require a blacklist that stops other apps working.

Seems like commonsense to me…

VirtualBox needs access to the hypervisor : Intel VT-x or AMD-V … You can’t really have two products competing and running services at the same time that need access to the HyperVisor…

If you’re using KVM - then that should have exclusive use of the hypervisor layer / API. I guess it would be nice if Debian gave you that option - i.e. “do you want to enable KVM access to the HyperVisor?”

Windows is no different. You can’t run VMware Player/Workstation, if you’re using HyperV… I had this issue a few years back where the corporate Windows 10 SOE used HyperV - so VirtualBox didn’t have access to the HyperVisor - you could only do 32 bit VirtualBox guests…

If it was possible - it would be an attack vector from malicious players… e.g. VMware ESX servers run their Linux O/S “photon”… Imagine if something could come along and hook into the HyperVisor?

It’s just a shame that VirtualBox can’t use the KVM stuff built into every modern Linux kernel… Oh well… I’m glad I switched to KVM anyway…

[nevj (Neville Jackson)]

@daniel.m.tripp

You can’t really have two products competing and running services at the same time that need access to the HyperVisor…

OK… so this hypervisor hardware is rather special… like there is no problem having 2 processes access the cpu… the kernel looks after it and time shares… but I guess the kernel will not time share the hypervisor? … but it must… I can run 2 VM’s simultaneously both using KVM.

You have the solution

@daniel.m.tripp

It’s just a shame that VirtualBox can’t use the KVM stuff built into every modern Linux kernel

Vbox should make its Linux version do things the Linux way.

[daniel.m.tripp (Dan Tripp)]

@nevj

but I guess the kernel will not time share the hypervisor? … but it must… I can run 2 VM’s simultaneously both using KVM.

Both are accessing the KVM stuff in the Linux kernel… But you can’t have KVM and some other virtualization product (that uses Intel VT-x or AMD-V) accessing the hypervisor at the same time… As I mentioned - that would probably be an attack vector…

I’ve no idea if Photon (VMware’s Linux) uses KVM or implements it’s own thing like VirtualBox does… Hmmm - it’s years since I used VMware Workstation - I can’t remember what it was like… But that’s different again from VM Photon / ESX…

---

Hmmm - just learned something… VMware ESX doesn’t use the Linux kernel… I uses its own microkernel…

Now I remember - PhotonOs is the Linux “distro” that VMware runs on vCenter servers… ESX is not Linux… There was a German kernel developer who tried to sue VMware for GPL copyright infringement, and was dismissed 3 times by German courts…