[libvirt] [RFC] get guest OS infos

[Daniel P. Berrange]

On Fri, Jun 12, 2015 at 04:56:17PM +0800, zhang bo wrote:
> On 2015/6/11 21:54, Daniel P. Berrange wrote:
> 
> > On Thu, Jun 11, 2015 at 08:47:12AM -0500, Dennis Jenkins wrote:
> >> On Thu, Jun 11, 2015 at 3:51 AM, Daniel P. Berrange <berrange at redhat.com>
> >> wrote:
> >>
> >>> On Thu, Jun 11, 2015 at 09:17:30AM +0100, Daniel P. Berrange wrote:
> >>>> On Thu, Jun 11, 2015 at 01:51:33PM +0800, zhang bo wrote:
> >>>>> Different OSes have different capabilities and behaviors sometimes. We
> >>> have to distinguish them then.
> >>>>>
> >>>>> For example, our clients want to send NMI interrupts to certain
> >>> guests(eg.Linux distributions), but not others(eg.Windows guests).
> >>>>> They want to acquire the list below:
> >>>>>   guest1: RHEL 7
> >>>>>   guest2: RHEL 7
> >>>>>   guest3: Ubuntu 12
> >>>>>   guest4: Ubuntu 13
> >>>>>   guest5: Windows 7
> >>>>>   ......
> >>>>>
> >>>>> AFAIK, neither libvirt nor openstack, nor qemu, have such capbility of
> >>> showing these guest OS infos.
> >>>>> Libvirt now supports to show host capabilities and driver capability,
> >>> but not an individual guest OS's capibility. We may refer to
> >>>>> http://libvirt.org/formatdomaincaps.html for more information.
> >>>>>
> >>>
> >>
> >> Hello.  I wrote a utility a few years ago to detect which OS is running in
> >> each qemu VM under libvirt via memory probing.  I have not touched the code
> >> in a few years.  YMMV.
> >>
> >> http://pastebin.com/m0mfcK8G
> > 
> > FWIW, you can also use libguestfs to analyse the disk of a libvirt guest
> > while it is running, if you libguestfs' use readonly mode
> > 
> > Regards,
> > Daniel
> 
> 
> Great. It seems much better to have Glance and libosinfo together  to get guest osinfo, 
> because you don't have to start the guest to get its osinfo, that's attracting.
> 
> I just have one question: It uses Glance to set os-name, and let libosinfo search its database to 
> get further more infos(I don't know if I'm right here). Is there any possibility that we set a false
>  os-name to image by Glance, for example, the guest is fedora12, but we set it to Ubuntu13 via Glance.

It of course relies on the user setting the correct operating system
name for their image. If the user sets this wrong, then the guest
may end up getting the wrong hardware config.

> and, when would this feature be implemented in Openstack? Thanks.

It is under review

https://review.openstack.org/#/q/status:open+project:openstack/nova+branch:master+topic:bp/libvirt-hardware-policy-from-libosinfo,n,z

NB, this only covers configuration of disk & network drivers. In the future
we'll extend it to other interesting things

Regards,
Daniel
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