[Libosinfo] [osinfo-db PATCH] RFC: schema: Add support to Guest Features

[Daniel P. Berrangé]

On Fri, Nov 16, 2018 at 02:33:03PM -0500, Cole Robinson wrote:
> On 11/15/2018 06:04 AM, Fabiano Fidêncio wrote:
> > One of the requests that came from KubeVirt is that would be really nice
> > if we could expose Guest supported features.
> > 
> > In order to do so, I came up with this *prototype* and I'd like to ask
> > for some review of the schema before I actually start implementing
> > something on libosinfo side.
> > 
> > One example of how it'll look like is:
> > <os>
> >    <features>
> >      <feature removed="true">device-hotplug</feature>
> >      <feature>cpu-hotplug</feature>
> >      <feature>NUMA</feature>
> >    </features>
> > </os>
> > 
> > > From the start:
> > - features *will* be inrited between OSes, by default.
> > - the feature element has an optional "removed" attribute which, by
> > default, is "false".
> > 
> > Is this approach okay?
> > 
> 
> ACK, this looks like what I imagined as well. It will work like <devices>
> but just advertises unique string values. The main thing for us will be to
> thoroughly document the semantics of each string value.
> 
> The term 'feature' is kinda misleading because I can see this functionality
> being used to advertise anti-features, like an OS bug that affects guest
> config. I listed some cases here[1]. But I can't think of anything better,
> and I doubt there's any single term that can cover all possible usages of
> this functionality without being meaningless, so I'm cool with 'feature'

The 'removed' attribute could be changed to deal with anti features in a
saner way, by calling it "supported" as a boolean.

   <feature supported="yes|no">cpu-hotplug</feature>

IOW, an anti-feature is simply a feature with supported=no

> [1]: https://www.redhat.com/archives/libosinfo/2018-September/msg00002.html

Regards,
Daniel
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