On Thu, 8 May 2025 15:35:25 +0200
Philippe Mathieu-Daudé <phi...@linaro.org> wrote:
> The PCMachineClass::legacy_cpu_hotplug boolean was only used
> by the pc-q35-2.6 and pc-i440fx-2.6 machines, which got
> removed. Remove it and simplify build_dsdt(), removing
> build_legacy_cpu_hotplug_aml() altogether.
>
> Note, this field was added by commit 679dd1a957d ("pc: use
> new CPU hotplug interface since 2.7 machine type"):
>
> > For compatibility reasons PC/Q35 will start with legacy
> > CPU hotplug interface by default but with new CPU hotplug
> > AML code since 2.7 machine type. That way legacy firmware
> > that doesn't use QEMU generated ACPI tables will be
> > able to continue using legacy CPU hotplug interface.
> >
> > While new machine type, with firmware supporting QEMU
> > provided ACPI tables, will generate new CPU hotplug AML,
> > which will switch to new CPU hotplug interface when
> > guest OS executes its _INI method on ACPI tables
> > loading.
>
> Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
> Reviewed-by: Mark Cave-Ayland <mark.caveayl...@nutanix.com>
> Reviewed-by: Thomas Huth <th...@redhat.com>
> Reviewed-by: Zhao Liu <zhao1....@intel.com>
> ---
> include/hw/acpi/cpu_hotplug.h | 3 -
> include/hw/i386/pc.h | 3 -
> hw/acpi/cpu_hotplug.c | 230 ----------------------------------
> hw/i386/acpi-build.c | 4 +-
> 4 files changed, 1 insertion(+), 239 deletions(-)
>
...
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 3fffa4a3328..625889783ec 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1465,9 +1465,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> }
> aml_append(dsdt, scope);
>
> - 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,
^^^^^
that still leaves legacy CPU hotplug hardware around, which we should remove
at the same time as legacy AML.
i.e.:
drop _INI in hw/acpi/cpu.c
and at the same time replace legacy_acpi_cpu_hotplug_init() at call sites with
cpu_hotplug_hw_init()
after that you can safely remove legacy_cpu_hotplug and no longer needed
hw/acpi/cpu_hotplug.c && co
> .smi_path = pm->smi_on_cpuhp ? "\\_SB.PCI0.SMI0.SMIC" : NULL,
