[libvirt] [PATCH v4 2/5] libxl: add support for PVH

[Daniel P. Berrangé]

On Thu, Oct 18, 2018 at 11:08:34AM -0600, Jim Fehlig wrote:
> On 10/17/18 12:59 PM, Marek Marczykowski-Górecki wrote:
> > On Sat, Oct 13, 2018 at 08:46:19AM -0600, Jim Fehlig wrote:
> > > I had some couch time at the start of the weekend and was finally able to
> > > try using this series with virt-install. As it turns out, reporting
> > > duplicate <guest> blocks for <os_type> 'xen' is not quite right. Instead we
> > > will want to report the additional <machine> under the existing 'xen'
> > > <guest> blocks.
> > 
> > Is that virt-install limitation? In that case, IMO virt-install should
> > be fixed, instead of changing capabilities xml to match its limitations.
> 
> Perhaps it is a virt-install limitation, but my suggestion was based more on
> how the qemu driver reports the different machines
> 
> <guest>
>   <os_type>hvm</os_type>
>   <arch name='x86_64'>
>     <wordsize>64</wordsize>
>     <emulator>/usr/bin/qemu-system-x86_64</emulator>
>     <machine maxCpus='255'>pc-i440fx-3.0</machine>
>     <machine maxCpus='288'>pc-q35-3.0</machine>
>     ...
>   </arch>
> </guest>
> 
> Compare that with reporting PV and PVH in different <guest> blocks, where
> the <os_type> and <arch> are the same. It seems confusing from a consumers
> POV
> 
> <guest>
>   <os_type>xen</os_type>
>   <arch name='x86_64'>
>     <wordsize>64</wordsize>
>     <emulator>/usr/bin/qemu-system-x86_64</emulator>
>     <machine>xenpv</machine>
>   </arch>
> </guest>
> 
> <guest>
>   <os_type>xen</os_type>
>   <arch name='x86_64'>
>     <wordsize>64</wordsize>
>     <emulator>/usr/bin/qemu-system-x86_64</emulator>
>     <machine>xenpvh</machine>
>   </arch>
> </guest>
> 
> How should a consumer interpret that? Is the machine for os_type=xen,
> arch=x86_64 a xenpv or a xenpvh?

Yes, you are right - any pair of (os_type, arch) should be unique
in the capabilities XML. So all machines should be reported in the
same block.

Regards,
Daniel
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