| 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. |
