general/other FreeBSD + qemu+ kvm + nested virtualization support

ZioMario

ZioMario

Hello. I would ask you some questions :

1) what's the latest Freebsd version able to support qemu + kvm ? I read that kvm has been removed on 2016,so it should be 10 or 11. It was also able to support nested virtualization ?

thanks.
 
Unfortunately there's no KVM support for qemu on FreeBSD.

Edit: to see what acceleration you have built in (not necessarily available afaik) you can do qemu-system-x86_64 -accel help. Assuming you want to run x86 guest.
 
but here : https://www.linux-kvm.org/page/BSD
you can read by yourself :

kqemu on BSD​

FreeBSD

Note: the kqemu-kmod port was removed in 2016 with the following comment:

> The are broken on recent FreeBSD, they are not supported by any qemu version, they do not build with recent binutils (2.27)

So,if I get a FreeBSD version that has been produced before 2016,I will find kqemu-kmod. that's right ?
 
Well nothing from 2016 is supported anymore so that'll be tough luck. Not sure you'd gain much from that either (security risks excluded). You triggered a small flashback in my head though -- I do remember installing vmware3 on FreeBSD and I liked it. FreeBSD 5 or 6 it was ? Don't remember..

If you do need some sort of acceleration I'd stick with bhyve or VirtualBox on FreeBSD. And I'm saying that as very big fan of qemu.
Personally on machines where I need accelerated qemu I chose Linux.
 
During the years I've switched slowly from Windows to Linux and from Linux to FreeBSD. Sure,there are OSes with which I can do some tasks faster and easier than others and I could use them. But If I'm able to learn and to configure very well the OS that I like more (at the moment is FreeBSD) I think that I can do everything only with it. I want to use Linux rarely,because I prefer the simplicity to complications. I can accept a certain amount of complications only if they correspond to the activation of certain features that I particularly love to have. I don't like VirtualBOX. Bhyve is better. At the moment qemu+kvm on Linux is the better choice,but bhyve is almost comparable.

Code: 
# qemu-system-x86_64 -accel help

Accelerators supported in QEMU binary:
tcg

:(
 
ruby R53 said:
i apologize for necroposting here, but

do you know why that is? i'm so used to QEMU i can't bother learning how to use bhyve at the moment
Click to expand...
I love qemu, absolute swiss knife of debugging too. qemu monitor is killer feature.
I can't give you advice what you should or shouldn't spend your time on ;). We are on FreeBSD forums, you probably know what the advice from most people would be. For me it's about what I'm used to, what I do and what software allows me to do. You know, "use tools that best enable your success" thing. That's qemu all the way for me.

When it comes to performance most likely you get the same performance as you would get from any other supported hypervisor out there.
 
Do you know that someone,for the GSOC 2025, created some code to accelerate qemu with bhyve ? I think it's cool. Soon I will try to study the code because I want to improve it.
 
You are mixing things here ZioMario. bhyve ≠ vmm.

If somebody created code in qemu that can leverage vmm and have full support of FreeBSD dev team, that would be awesome. But since all hands are focused on inhouse product of bhyve I would not hold my breath for it.

ZioMario said:
Soon I will try to study the code because I want to improve it.
Click to expand...
While noble idea I doubt it.
 
_martin said:
You are mixing things here ZioMario. bhyve ≠ vmm.

If somebody created code in qemu that can leverage vmm and have full support of FreeBSD dev team, that would be awesome. But since all hands are focused on inhouse product of bhyve I would not hold my breath for it.


While noble idea I doubt it.
Click to expand...

I'm not expert,but I think It's wrong to say "qemu accelerated with bhyve". I think it's more correct to say "qemu accelerated with vmm or whatever...with a specific part of bhyve,I think it is the code that strictly refers to the hypervisor" ? You can read by your own here :

summerofcode.withgoogle.com

Google Summer of Code

Google Summer of Code is a global program focused on bringing more developers into open source software development.
summerofcode.withgoogle.com summerofcode.withgoogle.com

title : VMM Accelerator support for QEMU

So,I'm not mixing anything. It's VMM that plays,not bhyve.

While noble idea I doubt it.
Click to expand...

Most of the code has been written. I will try to improve it using the IA,for sure. I'm not able to code at that level.
 
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