[CentOS-virt] CentOS-5.4, KVM, QEMU, Virt-Manager and kvm-qemu-img

James B. Byrne byrnejb at harte-lyne.ca
Tue Nov 10 01:46:15 UTC 2009

On Mon, November 9, 2009 20:31, Kai Schaetzl wrote:
> James B. Byrne wrote on Mon, 9 Nov 2009 16:23:55 -0500 (EST):
>> Lastly, why is qemu 4.5M but kvm-qemu-img is only 125K?
> I would assume it's just the module that works on image files.
> AFAIK, you don't need qemu if you have KVM. The same way you
> don't need KVM if you use Xen ...

This is not the sense I gather from the various kvm websites.  For
example, http://www.linux-kvm.org/page/Main_Page states this:

"KVM also requires a modified QEMU although work is underway to get
the required changes upstream."

Now, I am not sure what this means as I lack any context.  Does it
mean that one needs a specialized qemu now and expresses hope that
the standard qemu will incorporate the necessary changes sometime
later?  Or does it mean that qemu is needed now but that no qemu
will be needed when "upstream" incorporates the recommended changes?
 As the date of this text is not later than 2008 July 21 is it out
of date? Have the necessary changes been incorporated by upstream by

Since upstream is not defined it may mean the qemu project or it
might refer to the Linux kernel team.  I suspect that the former is
the case and that qemu will be required to support kvm in the
foreseeable future, if not forever.

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