1QEMU<->ACPI BIOS memory hotplug interface 2-------------------------------------- 3 4ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add 5and hot-remove events. 6 7Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access): 8--------------------------------------------------------------- 90xa00: 10 read access: 11 [0x0-0x3] Lo part of memory device phys address 12 [0x4-0x7] Hi part of memory device phys address 13 [0x8-0xb] Lo part of memory device size in bytes 14 [0xc-0xf] Hi part of memory device size in bytes 15 [0x10-0x13] Memory device proximity domain 16 [0x14] Memory device status fields 17 bits: 18 0: Device is enabled and may be used by guest 19 1: Device insert event, used to distinguish device for which 20 no device check event to OSPM was issued. 21 It's valid only when bit 1 is set. 22 2: Device remove event, used to distinguish device for which 23 no device eject request to OSPM was issued. 24 3-7: reserved and should be ignored by OSPM 25 [0x15-0x17] reserved 26 27 write access: 28 [0x0-0x3] Memory device slot selector, selects active memory device. 29 All following accesses to other registers in 0xa00-0xa17 30 region will read/store data from/to selected memory device. 31 [0x4-0x7] OST event code reported by OSPM 32 [0x8-0xb] OST status code reported by OSPM 33 [0xc-0x13] reserved, writes into it are ignored 34 [0x14] Memory device control fields 35 bits: 36 0: reserved, OSPM must clear it before writing to register. 37 Due to BUG in versions prior 2.4 that field isn't cleared 38 when other fields are written. Keep it reserved and don't 39 try to reuse it. 40 1: if set to 1 clears device insert event, set by OSPM 41 after it has emitted device check event for the 42 selected memory device 43 2: if set to 1 clears device remove event, set by OSPM 44 after it has emitted device eject request for the 45 selected memory device 46 3: if set to 1 initiates device eject, set by OSPM when it 47 triggers memory device removal and calls _EJ0 method 48 4-7: reserved, OSPM must clear them before writing to register 49 50Selecting memory device slot beyond present range has no effect on platform: 51 - write accesses to memory hot-plug registers not documented above are 52 ignored 53 - read accesses to memory hot-plug registers not documented above return 54 all bits set to 1. 55 56Memory hot remove process diagram: 57---------------------------------- 58 +-------------+ +-----------------------+ +------------------+ 59 | 1. QEMU | | 2. QEMU | |3. QEMU | 60 | device_del +---->+ device unplug request +----->+Send SCI to guest,| 61 | | | cb | |return control to | 62 +-------------+ +-----------------------+ |management | 63 +------------------+ 64 65 +---------------------------------------------------------------------+ 66 67 +---------------------+ +-------------------------+ 68 | OSPM: | remove event | OSPM: | 69 | send Eject Request, | | Scan memory devices | 70 | clear remove event +<-------------+ for event flags | 71 | | | | 72 +---------------------+ +-------------------------+ 73 | 74 | 75 +---------v--------+ +-----------------------+ 76 | Guest OS: | success | OSPM: | 77 | process Ejection +----------->+ Execute _EJ0 method, | 78 | request | | set eject bit in flags| 79 +------------------+ +-----------------------+ 80 |failure | 81 v v 82 +------------------------+ +-----------------------+ 83 | OSPM: | | QEMU: | 84 | set OST event & status | | call device unplug cb | 85 | fields | | | 86 +------------------------+ +-----------------------+ 87 | | 88 v v 89 +------------------+ +-------------------+ 90 |QEMU: | |QEMU: | 91 |Send OST QMP event| |Send device deleted| 92 | | |QMP event | 93 +------------------+ | | 94 +-------------------+ 95