Re: [Qemu-devel] [qemu-devel][libvirt] Default machine type setting for ppc64

[Anthony Liguori <anthony@codemonkey.ws>]

"Daniel P. Berrange" <berrange@redhat.com> writes:

> On Tue, May 21, 2013 at 07:55:27PM +1000, Paul Mackerras wrote:
>> On Tue, May 21, 2013 at 09:39:53AM +0100, Daniel P. Berrange wrote:
>> I think libvirt needs some more sensible way to ask qemu what its
>> capabilities are.  Currently it has no way to ask qemu "what machines
>> can you emulate with kvm acceleration?"  If the user has asked for a
>> KVM domain then the default machine should be one that can be provided
>> by KVM.  At present it isn't, on PowerPC.
>
> If QEMU can provide more intelligent info in this respect, then
> libvirt can use it. We're doing the best we can with picking
> defaults given the info QEMU currently provides us.

Thinking about this a little more.

OpenStack pushes a lot of configuration to the nodes themselves instead
of making things dynamic and exposing APIs (think host network
configuration).

QEMU actually does allow a user to change the default machine type via
the global config file so in theory you could do this with OpenStack.

However, since libvirt uses -nouserconfig, this doesn't work in
practice.

Perhaps the right thing to do for OpenStack is to allow for a user
specified configuration file to select things like the default hardware
models/machine types?  Then this could become node configuration instead
of dynamic configuration.

I think it could be useful for general users too.  Every domain requires
a lot of the same boiler plate bits.  I think a lot of configurations
would benefit from being able to set global domain options.

Regards,

Anthony Liguori

>
>
> Daniel
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