qemu/docs/specs/acpi_cpu_hotplug.txt
Igor Mammedov b8622725cf acpi_piix4: Add infrastructure to send CPU hot-plug GPE to guest
* introduce processor status bitmask visible to guest at 0xaf00 addr,
  where ACPI asl code expects it
* set bit corresponding to APIC ID in processor status bitmask on
  receiving CPU hot-plug notification
* trigger CPU hot-plug SCI, to notify guest about CPU hot-plug event

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
2013-05-01 13:04:18 +02:00

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QEMU<->ACPI BIOS CPU hotplug interface
--------------------------------------
QEMU supports CPU hotplug via ACPI. This document
describes the interface between QEMU and the ACPI BIOS.
ACPI GPE block (IO ports 0xafe0-0xafe3, byte access):
-----------------------------------------
Generic ACPI GPE block. Bit 2 (GPE.2) used to notify CPU
hot-add/remove event to ACPI BIOS, via SCI interrupt.
CPU present bitmap (IO port 0xaf00-0xae1f, 1-byte access):
---------------------------------------------------------------
One bit per CPU. Bit position reflects corresponding CPU APIC ID.
Read-only.
CPU hot-add/remove notification:
-----------------------------------------------------
QEMU sets/clears corresponding CPU bit on hot-add/remove event.
CPU present map read by ACPI BIOS GPE.2 handler to notify OS of CPU
hot-(un)plug events.