Re: [RFC PATCH v2 5/6] hw/arm/virt-acpi-build: Add PPTT table

[Andrew Jones]

On Thu, May 13, 2021 at 01:10:10PM +0800, wangyanan (Y) wrote:
> >   /* GTDT */
> >   static void
> >   build_gtdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> > @@ -707,6 +765,11 @@ void virt_acpi_build(VirtMachineState *vms, 
> > AcpiBuildTables *tables)
> >       acpi_add_table(table_offsets, tables_blob);
> >       build_madt(tables_blob, tables->linker, vms);
> > +    if (ms->smp.cpus > 1 && !vmc->no_cpu_topology) {
> I'm not really sure why we need to care about "ms->smp.cpus > 1" here?
> 
> IMO, just like MADT in which we create both ENABLED and DISABLED
> gicc nodes no matter of number of ENABLED nodes is one or not, we
> should create PPTT table for all the possible cpus and not care about
> number of smp cpus, too. This will be more consistent with the ACPI
> specification and the PPTT table will be used for ACPI cpu hotplug in
> the future even with  "smp.cpus == 1".
> 
> Care of "smp.cpus > 1" in the DT cpu-map part makes sense to me,
> because we are required to only add present cpu nodes to the DT and
> Linux Doc says that a cpu-map is not needed for uniprocessor systems.
> 

Hi Yanan,

You're right. Let's just always generate the PPTT.

Thanks,
drew