Just an intro.

Christopher Chaltain chaltain at gmail.com
Mon Mar 25 15:24:15 UTC 2013


OK, well I admit I may still have a lot to learn here. I was just going 
by what I read on pages like http://wiki.qemu.org/KVM where it says:

QEMU can make use of KVM when running a target architecture that is the 
same as the host architecture. For instance, when running 
qemu-system-x86 on an x86 compatible processor, you can take advantage 
of the KVM acceleration - giving you benefit for your host and your 
guest system.

I read this on multiple web sites, but you can't always tell what's 
current by reading a web page.


On 03/25/2013 03:47 AM, Tony Baechler wrote:
> No, it won't.  KVM and Qemu are two different packages, at least on
> Debian.  If you call qemu by itself, you don't use hardware
> virtualization.  If you call kvm without a kvm module loaded, it exits
> or falls back to Qemu. Perhaps this has changed with newer versions of
> Qemu, but every version of Qemu I've used is separate from KVM.
> However, I think they merged the Qemu and KVM code, so you might be
> right nowadays.  There is a difference though and they aren't the same
> thing.  Even in Debian and Ubuntu, you install qemu-kvm, qemu-system and
> qemu-user if you want a full Qemu and KVM setup.
>
> You might be thinking of the kernel Qemu module, but it is now abandoned
> and no longer recommended.  Debian no longer ships it, so it's either
> straight Qemu without virtualization or KVM if your CPU supports it.
> Not all hardware supports virtualization, even now.  ARM processors
> wouldn't, for example.  My CPU here on my desktop isn't that old and it
> doesn't, thus bringing me back to why I don't run Windows in a VM.  Even
> with KVM, there is a slight performance hit, but not much.
>
> On 3/24/2013 12:23 PM, Christopher Chaltain wrote:
>> Just a note that qemu will use kvm if hardware virtualization is
>> available,
>> so you won't get that performance hit with qemu in those cases.
>
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-- 
Christopher (CJ)
chaltain at Gmail




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