Re: [Qemu-devel] of apci_1_compatible in CPUHotplugFeatures

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jan 25, 2019 at 09:26:05AM +0100, Igor Mammedov wrote:
> On Wed, 23 Jan 2019 18:28:59 +0000
> "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> 
> > * Michael S. Tsirkin (mst@redhat.com) wrote:
> > > On Tue, Jan 22, 2019 at 08:07:41PM +0000, Dr. David Alan Gilbert wrote:  
> > > > Hi,
> > > >   I noticed that the acpi_1_compatible flag was misspelt as
> > > >                      apci_1_compatible
> > > > 
> > > > so have a trivial patch to fix that,
> pls post it.
> 
> > > > but looking at it - are
> > > > thre any cases where a[cp]i_1_compatible can possibly be false?
> ATM it's not possible, but I've wrote it with intent to reuse
> build_cpus_aml() in arm/virt board and there we shall use newer
> aml_device() instead of legacy aml_processor(), hence a feature flag
> to toggle behavior.

Are there imminent plans to do this? If not why don't we
drop unused code? One can always bring it back from git
history if need arises but for now there's no guarantee
it's not broken as it never runs.

> 
> > > > 
> > > > Dave  
> > > 
> > > legacy_cpu_hotplug so machine 2.6 and older - no?  
> > 
> > That doesn't seem to affect that flag by my reading;
> > the only place I see legacy_cpu_hotplug checked is
> > acpi-build.c:build_dsdt and we have:
> > 
> >     if (pcmc->legacy_cpu_hotplug) {
> >         build_legacy_cpu_hotplug_aml(dsdt, machine, pm->cpu_hp_io_base);
> >     } else {
> >         CPUHotplugFeatures opts = {
> >             .acpi_1_compatible = true, .has_legacy_cphp = true
> >         };
> >         build_cpus_aml(dsdt, machine, opts, pm->cpu_hp_io_base,
> >                        "\\_SB.PCI0", "\\_GPE._E02");
> >     }
> > 
> > so the 'opts' field is only used in the non-legacy case.
> > 
> > That's the only caller of build_cpus_aml, and I'm not seeing another
> > user of CPUHotplugFeatures.
> > 
> > Dave
> > 
> > > > --
> > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK  
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK