qemu/docs/specs/acpi_pci_hotplug.txt
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   1QEMU<->ACPI BIOS PCI hotplug interface
   2--------------------------------------
   3
   4QEMU supports PCI hotplug via ACPI, for PCI bus 0. This document
   5describes the interface between QEMU and the ACPI BIOS.
   6
   7ACPI GPE block (IO ports 0xafe0-0xafe3, byte access):
   8-----------------------------------------
   9
  10Generic ACPI GPE block. Bit 1 (GPE.1) used to notify PCI hotplug/eject
  11event to ACPI BIOS, via SCI interrupt.
  12
  13PCI slot injection notification pending (IO port 0xae00-0xae03, 4-byte access):
  14---------------------------------------------------------------
  15Slot injection notification pending. One bit per slot.
  16
  17Read by ACPI BIOS GPE.1 handler to notify OS of injection
  18events.  Read-only.
  19
  20PCI slot removal notification (IO port 0xae04-0xae07, 4-byte access):
  21-----------------------------------------------------
  22Slot removal notification pending. One bit per slot.
  23
  24Read by ACPI BIOS GPE.1 handler to notify OS of removal
  25events.  Read-only.
  26
  27PCI device eject (IO port 0xae08-0xae0b, 4-byte access):
  28----------------------------------------
  29
  30Write: Used by ACPI BIOS _EJ0 method to request device removal.
  31One bit per slot.
  32
  33Read: Hotplug features register.  Used by platform to identify features
  34available.  Current base feature set (no bits set):
  35 - Read-only "up" register @0xae00, 4-byte access, bit per slot
  36 - Read-only "down" register @0xae04, 4-byte access, bit per slot
  37 - Read/write "eject" register @0xae08, 4-byte access,
  38   write: bit per slot eject, read: hotplug feature set
  39 - Read-only hotplug capable register @0xae0c, 4-byte access, bit per slot
  40
  41PCI removability status (IO port 0xae0c-0xae0f, 4-byte access):
  42-----------------------------------------------
  43
  44Used by ACPI BIOS _RMV method to indicate removability status to OS. One
  45bit per slot.  Read-only
  46