Intel Core2 Duo w/ vmx and KVM/Qemu: info needed

[VinzC]

Hi.

I have a Dell Inspiron 9400 with a Core2 Duo and virtualization enabled. I have compiled Gentoo Sources 2.6.21-r2 and added intel-kvm built-in to my kernel configuration.

I'd like to know if Qemu 0.9.0 can take profit from my CPU virtualization capabilities. BTW I am completely lost between KVM and Qemu. I've seen KVM is a program but it's also a kernel module that has been included since 2.6.20.

I've also seen many references between QEMU/KVM in which Qemu is a modified version but every link I've seen shows KVM is independent of Qemu and examples run KVM instead of Qemu

Can anybody clarify this a little bit for me, please?

Here are my questions:

• What is QEMU/KVM and how do they relate together?
  
• Can Qemu use a Core2 Duo virtualization capabilities?
  
• Does Qemu have anything to do with kernel module KVM?
  
• Can Qemu use kernel module KVM?
  
• What target CPU does qemu-system-x86_64 emulate? 32 or 64 bits?
  
• Can Qemu on a Core2 Duo emulate a 32-bit CPU?
  
• KVM and Xen are often associated in articles on the web. Is KVM for paravirtualization or just virtualization?

The fact is I have run Qemu both with virtualization enabled and disabled and I don't seem to see a difference when I run my W2K virtual machine. There is a windows service, csrss, which constantly consumes CPU (around 5-12%).
_________________
Gentoo addict: tomorrow I quit, I promise!... Just one more emerge...
1739!

[Baribeault]

What is QEMU/KVM and how do they relate together?
KVM is a kernel module that add functionaly to QEMU. KVM cannot be without QEMU.

Can Qemu use a Core2 Duo virtualization capabilities?
No. But KVM can with kvm_intel module.

Does Qemu have anything to do with kernel module KVM?
No. But KVM need Qemu for virtualization.

Can Qemu use kernel module KVM?
Yes.

What target CPU does qemu-system-x86_64 emulate? 32 or 64 bits?
It can do both as far I know.

Can Qemu on a Core2 Duo emulate a 32-bit CPU?
Yes.

KVM and Xen are often associated in articles on the web. Is KVM for paravirtualization or just virtualization?
Paravirtualization is in progress for KVM, for now it is just virtualization but soon it will support paravirtualization.

P.S. Don't use the in kernel module, download the most recent KVM source and compile and install. A much better approach because of the speed of KVM development.

[VinzC]

Thanks for your replies. Would you mind going on for further questions?

[Jjeje007]

Hi,

kvm user space ebuild (work in progress) :

https://bugs.gentoo.org/show_bug.cgi?id=157987

Jjeje007

[rmh3093]

[VinzC]

Thanks for your lights rmh3093.

I think I understood Windows could run under paravirtualized environment provided the CPU had virtualization abilities (like vmx for Intel). I thought that as soon as one had such a CPU Windows + Paravirtualization was possible, is that correct? Unless it means only KVM is not ready for running Windows under paravirtualization but Xen is? Erm... is Xen ready for that BTW?
_________________
Gentoo addict: tomorrow I quit, I promise!... Just one more emerge...
1739!

[Bones]

Paravirtualization requires a guest kernel that is aware that it is running in a virtualized environment, and can use the paravirt interface of the host kernel. So the question should be "Is Windows ready to run as a paravirtualized guest on KVM?" And the answer is no. But it can be run as a normal, fully virtualized guest.

I recommend compiling the KVM userspace and kernel module from the source tarball. The kernel module included in 2.6.22 doesn't have the recent performance enhancements, which make a very large difference.
_________________
I have a computer.

[rmh3093]

[tomekki]

Hi,
your answers brought some light in the dark for me as well.
I have a question of my own. Is it possible to run kvm with kernel support by kqemu?
I managed to run kvm, but I am not sure whether the ring 0 operations are managed by the kqemu kernel module or not. It follows what I tried so far.

First I compiled a kernel with kvm support, then I emerged and loaded kqemu-1.3.0_pre11:

[Bones]

KVM has nothing to do with kqemu. The KVM module completely replaces it, that's why support for kqemu is not in KVM's version of QEMU.
_________________
I have a computer.

[tomekki]

Got it, thanks for your answer.

The explanation form http://kvm.qumranet.com/kvmwiki just confused me:

[VinzC]

[ciphermonk]

From what I've read on LKML, you have to pass the kvm-paravirt=1 boot option to the kernel to enable paravirt under KVM? Is this the case? Once paravirt is enabled in the kernel, do you simply use virt-manager to install the guests?

[darkphader]

[rmh3093]

[VinzC]

[tomekki]

Hi ciphermonk,
where have you red about the kernel parameter?

[rmh3093]