[libvirt] [RFC 4/6] conf: Expose GIC capabilities

[Cole Robinson]

On 04/06/2016 10:39 AM, Andrea Bolognani wrote:
> On Wed, 2016-03-30 at 16:10 -0400, John Ferlan wrote:
>>> diff --git a/tests/domaincapsschemadata/domaincaps-qemu_1.6.50-1.xml b/tests/domaincapsschemadata/domaincaps-
>>> qemu_1.6.50-1.xml
>>> index 37d2102..990661b 100644
>>> --- a/tests/domaincapsschemadata/domaincaps-qemu_1.6.50-1.xml
>>> +++ b/tests/domaincapsschemadata/domaincaps-qemu_1.6.50-1.xml
>>> @@ -56,4 +56,7 @@
>>>         </enum>
>>>       </hostdev>
>>>     </devices>
>>> +  <features>
>>> +    <gic supported='no'/>
>>> +  </features>
>>>   </domainCapabilities>
>>  
>> I first wondered why the XML file was modified, but later understood -
>> sort of...
> 
> We will need more tests for the new feature, of course.
> 
> I wanted to gather feedback on the interface with the RFC
> before I spent too much time testing or documenting it.
> 
>> Still not fully clear on how what this schema output should
>> look like... For prior to 2.6 should it even be printed?  For 2.6 and
>> beyond what would it look like?
> 
> There might be a case for not printing it, but we don't
> perform such optimization for the rest of the information
> that's part of domain capabilities, so I'm not sure
> whether we should bother in this case.
> 
> Versions prior to 2.6, and 2.6 itself on non-ARM
> architectures would yield
> 
>   <features>
>     <gic supported='no'/>
>   </features>
> 
> whereas 2.6 onward on ARM would yield something like
> 
>   <features>
>     <gic supported='yes'>
>       <enum name='version'>
>         <value>2</value>
>       </enum>
>     </gic>
>   </features>
> 
> which mirrors exactly the type of <gic> element the
> user can expect to be able to use inside the <feature>
> element in the domain XML, eg.
> 
>   <features>
>     <gic version='2'/>
>   </features>
> 

Unfortunately there's not a ton of prior art WRT domcapabilities to go off of,
but FWIW with my virt-manager/libvirt consumer hat on that all seems sensible
for the domcaps schema. It mirrors the domain XML, and reports the actual
values we will want to pass to the domain XML, so we don't need to translate
between magic strings or anything.

- Cole