Unfortunately I need to run virtual system on the machine without hardware support for visualisation. From kvm page I read that kvm is needed however it is not mentioned whether they mean the kernel support or the page was written before qemu started using kvm and virtio.

I have the kvm module loaded but machine is too old to have hardware support (AMD Opteron 148). I run into problems when I tried to use virtio.

  • Gilles: I don't need information about "what do I need to use KVM" but "what do I need to use Virtio". As historically both were developed concurrently and virtually any x86 computer now have support for kvm (just not the one I'm using :( ) I found hard to find if virtio requires enabled kvm or can it run separately with plain qemu. – Maciej Piechotka Dec 7 '11 at 13:46
  • Sorry, I shouldn't try to read questions at 1am. – Gilles 'SO- stop being evil' Dec 7 '11 at 15:29

if the host doesn't support AMD-V, you cannot use kvm there, all you can use is qemu in emulation mode. Even if you have the kvm module loaded, you also need kvm_amd, and it will not load without AMD-V. virtio is irrelevant here, if kvm isn't running, you will not be able to improve performance anyhow.

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    I'm not sure why not. If there is no hardware support for virtualisation I should be still able to use paravirtualisation. From what I understand paravirtualisation should simply ommit the full hardware emulation and transform the interaction with hardware into interaction with OS (syscalls). Sure - I will get penalty for various things but it seems to be a separate problems (which might be combined into single interface - hence my question) - technically it is possible to run fully paravirtualised OS which does not use privilige instructions (linux containers?). – Maciej Piechotka Dec 7 '11 at 13:42
  • what you're talking about is true, but it has nothing to do with kvm. kvm is full virtualization only – dyasny Dec 7 '11 at 13:50
  • But the question is about paravirutalisation (virtio). It just if kvm is for some, non fundamental, reasons required (say qemu depends on kernel interfaces in kvm). Your answer is rather what kvm is for rather then direct reply that it is not needed. – Maciej Piechotka Dec 7 '11 at 14:10
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    wiki.libvirt.org/page/Virtio#Requirements - as you can see KVM is not required. You do need to formulate your questions better though, because "Do I need hardware support for KVM for virtio paravirtualisation" is very KVM specific – dyasny Dec 7 '11 at 15:37
  • dyasny: well - I wanted to know if I need KVM to help troubleshooting (it turned out yesterday that it was old SeaBIOS). – Maciej Piechotka Dec 7 '11 at 20:32

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