No functional change in practice, patch only aims to properly
document (in spec and code) intended usage of the reserved space.
The new field is to be used for 2 purposes:
- detection of modern CPU hotplug interface using
CPHP_GET_NEXT_CPU_WITH_EVENT_CMD command.
procedure will be described in follow up patch:
"acpi: cpuhp: spec: add typical usecases"
- for returning upper 32 bits of architecture specific CPU ID,
for new CPHP_GET_CPU_ID_CMD command added by follow up patch:
"acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command"
Change is backward compatible with 4.2 and older machines, as field was
unconditionally reserved and always returned 0x0 if modern CPU hotplug
interface was enabled.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1575896942-331151-8-git-send-email-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
e6d0c3ce68