diff options
Diffstat (limited to 'docs/specs/acpi_mem_hotplug.txt')
| -rw-r--r-- | docs/specs/acpi_mem_hotplug.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/docs/specs/acpi_mem_hotplug.txt b/docs/specs/acpi_mem_hotplug.txt new file mode 100644 index 0000000000..12909940cc --- /dev/null +++ b/docs/specs/acpi_mem_hotplug.txt @@ -0,0 +1,44 @@ +QEMU<->ACPI BIOS memory hotplug interface +-------------------------------------- + +ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add +events. + +Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access): +--------------------------------------------------------------- +0xa00: + read access: + [0x0-0x3] Lo part of memory device phys address + [0x4-0x7] Hi part of memory device phys address + [0x8-0xb] Lo part of memory device size in bytes + [0xc-0xf] Hi part of memory device size in bytes + [0x10-0x13] Memory device proximity domain + [0x14] Memory device status fields + bits: + 0: Device is enabled and may be used by guest + 1: Device insert event, used to distinguish device for which + no device check event to OSPM was issued. + It's valid only when bit 1 is set. + 2-7: reserved and should be ignored by OSPM + [0x15-0x17] reserved + + write access: + [0x0-0x3] Memory device slot selector, selects active memory device. + All following accesses to other registers in 0xa00-0xa17 + region will read/store data from/to selected memory device. + [0x4-0x7] OST event code reported by OSPM + [0x8-0xb] OST status code reported by OSPM + [0xc-0x13] reserved, writes into it are ignored + [0x14] Memory device control fields + bits: + 0: reserved, OSPM must clear it before writing to register + 1: if set to 1 clears device insert event, set by OSPM + after it has emitted device check event for the + selected memory device + 2-7: reserved, OSPM must clear them before writing to register + +Selecting memory device slot beyond present range has no effect on platform: + - write accesses to memory hot-plug registers not documented above are + ignored + - read accesses to memory hot-plug registers not documented above return + all bits set to 1. |