docs/specs/acpi_mem_hotplug.rst

1 QEMU<->ACPI BIOS memory hotplug interface
4 ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add
5 and hot-remove events.
7 Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access)
8 ----------------------------------------------------------------
13 [0x0-0x3]
15 [0x4-0x7]
17 [0x8-0xb]
19 [0xc-0xf]
21 [0x10-0x13]
37   3-7:
40 [0x15-0x17]
47 [0x0-0x3]
49   All following accesses to other registers in 0xa00-0xa17
51 [0x4-0x7]
53 [0x8-0xb]
55 [0xc-0x13]
78   4-7:
83 - write accesses to memory hot-plug registers not documented above are ignored
84 - read accesses to memory hot-plug registers not documented above return
87 Memory hot remove process diagram
88 ---------------------------------
92    +-------------+     +-----------------------+      +------------------+
94    |  device_del +---->+ device unplug request +----->+Send SCI to guest,|
97    +-------------+     +-----------------------+      +------------------+
99    +---------------------------------------------------------------------+
101    +---------------------+              +-------------------------+
104    | clear remove event  +<-------------+ for event flags         |
106    +---------------------+              +-------------------------+
109    +---------v--------+            +-----------------------+
111    | process Ejection +----------->+ Execute _EJ0 method,  |
113    +------------------+            +-----------------------+
116    +------------------------+      +-----------------------+
120    +------------------------+      +-----------------------+
123    +------------------+              +-------------------+
127    +------------------+              |                   |
128                                      +-------------------+