[libvirt] domain type "kvm" error

Daniel P. Berrange berrange at redhat.com
Sun Sep 7 19:20:42 UTC 2008

On Sun, Sep 07, 2008 at 09:10:54PM +0300, Rakotomandimby Mihamina wrote:
> Hi all,
> I use "ubuntu hardy" but I dont think the problem is specific to the 
> distribution I use.
> I installed KVM and libvirt as described here:
> https://help.ubuntu.com/community/KVM
> Following that method, created a domain, which dumps like this:
>   <domain type='qemu' id='1'>
>     <name>xp1</name>
>     ...
>   </domain>
> Launching the guest is OK, but it is as slow as if I directly launched

This is becuse of the type='qemu' attribute

>   $ qemu [options]
> I tried to launch:
>   $ kvm [options]
> and it is much faster
> My conclusion is that method on the Ubuntu documentation launches a qemu 
> without the use of kvm.

That is correct.

> I modified that XML dump, changing "qemu" with "kvm":
>   <domain type='kvm' id='1'>
>     <name>xp1</name>
>     ...
>   </domain>

You also need to set the 'emulator' path to point to the KVM binary
if its not already specified.

> I undefined the domain "xp1" and re-defined it with that new XML file.
> When I start the new defined domain:
>   virsh # start xp1
>   libvir: QEMU error : QEMU quit during console startup
>   qemu: unknowm parameter 'boot' in \
>         'file=/home/mihamina/xpjohnny.iso,if=ide,media=cdrom,boot=on'
>   error: Failed to start domain xp1

IIRC the Ubuntu libvirt is hardcoded to use -drive param for disks if the
type is 'kvm'. Latest libvirt will probe to see if this is supported or
not before using it.
> It's a Windows XP domain.
> My conclusion is:
> - When domain type is "qemu", qemu is called a certain way, without 
> syntax error
> - When domain type is "kvm", qemu/kvm is not called the same way and 
> among that, there are syntax errors.

Yes & no. Latest libvirt probes for whether -drive is supported, and
whether the boot= param is supported. The older version in Ubuntu doesn't
do this probe, and just toggles off type=qemu vs type=kvm

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