Re: [Qemu-devel] [PATCH 07/11] spapr: add hotplug interrupt machine options

[Michael Roth]

Quoting Bharata B Rao (2016-10-14 03:37:32)
> On Wed, Oct 12, 2016 at 06:13:55PM -0500, Michael Roth wrote:
> > This adds machine options of the form:
> > 
> >   -machine pseries,legacy-hotplug-events=true
> >   -machine pseries,legacy-hotplug-events=false
> > 
> > to denote whether or not we wish to force the use of "legacy" style
> > hotplug events, which are surfaced through EPOW interrupts instead of
> > a dedicated interrupt source, and lack certain features necessary,
> > mainly, for memory unplug support.
> > 
> > If false, QEMU will default to "legacy" style unless the guest
> > advertises support for the newer events via
> > ibm,client-architecture-support hcall during early boot.
> > 
> > For pseries-2.7 and earlier we default to true, for newer machine
> > types we default to false.
> > 
> > Signed-off-by: Michael Roth <address@hidden>
> > ---
> >  hw/ppc/spapr.c              | 31 +++++++++++++++++++++++++++++++
> >  include/hw/ppc/spapr.h      |  1 +
> >  include/hw/ppc/spapr_ovec.h |  1 +
> >  3 files changed, 33 insertions(+)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index f8cde92..d80a6fa 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1816,6 +1816,11 @@ static void ppc_spapr_init(MachineState *machine)
> > 
> >      spapr_ovec_set(spapr->ov5, OV5_FORM1_AFFINITY);
> > 
> > +    /* use dedicated HP event source if guest supports it */
> > +    if (spapr->use_hotplug_event_source) {
> > +        spapr_ovec_set(spapr->ov5, OV5_HP_EVT);
> 
> The above comment can be confusing. Here you really mean that
> the machine type version supports OV5_HP_EVT right ? Because
> guest support for the same is determined during cas call later.

What trying to get it across that support would only be enabled if the
guest indicates support for it later. What about something like:

/* advertise support for dedicated HP event source to guests */

> 
> Regards,
> Bharata.