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Diffstat (limited to 'docs/specs/acpi_cpu_hotplug.txt')
| -rw-r--r-- | docs/specs/acpi_cpu_hotplug.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/docs/specs/acpi_cpu_hotplug.txt b/docs/specs/acpi_cpu_hotplug.txt new file mode 100644 index 0000000000..5dec0c5010 --- /dev/null +++ b/docs/specs/acpi_cpu_hotplug.txt @@ -0,0 +1,22 @@ +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. |