[PATCH v1 3/4] qemu_domain.c: do not launch ppc64 guests with 'pmu' setting

[Daniel Henrique Barboza]

On 3/24/20 11:00 AM, Andrea Bolognani wrote:
> On Tue, 2020-03-24 at 09:27 -0300, Daniel Henrique Barboza wrote:
>> Andrea, I see that the behavior of the 'panic' device in the ppc64 XML is to
>> always add a:

[...]

>>
>> For the sake of completeness, I'll also mention that we can simply allow <pmu/> to be
>> declared in the XML, handling the <pmu state='on'/> inside the QEMU driver to not add the
>> bogus '.pmu' parameter for QEMU ppc64, forbid <pmu state='off'/> to be declared, and
>> nothing else. No auto-generation of XML indicating that the guest will support a PMU.
> 
> Looking again at how other architectures, specifically x86 and ARM,
> handle this, the PMU is generally enabled by default without this
> fact being reflected in the domain XML; the user can then go ahead
> and specifically ask for it to be turned on or off, at which point
> libvirt will add the relevant bits to the QEMU command line.
> 
> This is basically the second behavior you're describing above, and
> I think it would be perfectly fine if that's the one we would adopt
> for ppc64.
> 

I guess I'll roll with this one then. I will allow <pmu state='on'/> to be
declared in the XML without breaking QEMU. For <pmu state='off'/> I'll
throw an CONFIG_UNSUPPORTED error mentioning that PMU can't be turned off
for ppc64.


Thanks,


DHB