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Re: Virtual Box



Mike Cloaked wrote:
> However the box I wanted to try this on does not have the hardware
> virtualisation flags that are the first test in the documentation for
> running KVM.  The question I am unclear about is whether KVM can still be
> used but give very slow performance, or does not having the "vmx" flag
> mean you can't use KVM at all?

Well, you can use QEMU and it will be extremely slow. I think the qemu-kvm
binary will fallback to software QEMU emulation if KVM is not supported.

One thing you can use to speed it up a bit in kmod-kqemu which you can found
in the RPM Fusion repository, in the Free section (it got GPLed some time
ago, so it's in the Free section, but Fedora won't carry it because it's
not in the upstream kernel). It's a hack to run some of the code on the
native hardware without needing hardware virtualization. That said, I'm not
sure whether virt-manager will fire up the correct qemu binary and with the
correct options to use kqemu. If you run the regular qemu binary (not
qemu-kvm) with no option, it will pick up kqemu.

That said, AFAIK kqemu doesn't perform anywhere near as well as KVM, also
because kernel code is still emulated entirely in software (there's an
experimental -kernel-kqemu option which tries to use kqemu also for
kernel-space code, but all I ever got out of that option is VM crashes).

        Kevin Kofler


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