129 lines
4.5 KiB
ReStructuredText
129 lines
4.5 KiB
ReStructuredText
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QEMU<->ACPI BIOS memory hotplug interface
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=========================================
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ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add
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and hot-remove events.
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Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access)
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----------------------------------------------------------------
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Read access behavior
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^^^^^^^^^^^^^^^^^^^^
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[0x0-0x3]
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Lo part of memory device phys address
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[0x4-0x7]
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Hi part of memory device phys address
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[0x8-0xb]
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Lo part of memory device size in bytes
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[0xc-0xf]
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Hi part of memory device size in bytes
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[0x10-0x13]
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Memory device proximity domain
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[0x14]
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Memory device status fields
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bits:
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0:
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Device is enabled and may be used by guest
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1:
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Device insert event, used to distinguish device for which
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no device check event to OSPM was issued.
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It's valid only when bit 1 is set.
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2:
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Device remove event, used to distinguish device for which
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no device eject request to OSPM was issued.
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3-7:
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reserved and should be ignored by OSPM
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[0x15-0x17]
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reserved
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Write access behavior
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^^^^^^^^^^^^^^^^^^^^^
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[0x0-0x3]
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Memory device slot selector, selects active memory device.
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All following accesses to other registers in 0xa00-0xa17
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region will read/store data from/to selected memory device.
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[0x4-0x7]
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OST event code reported by OSPM
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[0x8-0xb]
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OST status code reported by OSPM
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[0xc-0x13]
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reserved, writes into it are ignored
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[0x14]
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Memory device control fields
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bits:
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0:
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reserved, OSPM must clear it before writing to register.
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Due to BUG in versions prior 2.4 that field isn't cleared
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when other fields are written. Keep it reserved and don't
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try to reuse it.
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1:
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if set to 1 clears device insert event, set by OSPM
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after it has emitted device check event for the
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selected memory device
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2:
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if set to 1 clears device remove event, set by OSPM
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after it has emitted device eject request for the
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selected memory device
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3:
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if set to 1 initiates device eject, set by OSPM when it
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triggers memory device removal and calls _EJ0 method
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4-7:
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reserved, OSPM must clear them before writing to register
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Selecting memory device slot beyond present range has no effect on platform:
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- write accesses to memory hot-plug registers not documented above are ignored
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- read accesses to memory hot-plug registers not documented above return
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all bits set to 1.
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Memory hot remove process diagram
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---------------------------------
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::
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+-------------+ +-----------------------+ +------------------+
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| 1. QEMU | | 2. QEMU | |3. QEMU |
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| device_del +---->+ device unplug request +----->+Send SCI to guest,|
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| | | cb | |return control to |
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| | | | |management |
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+-------------+ +-----------------------+ +------------------+
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+---------------------------------------------------------------------+
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+---------------------+ +-------------------------+
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| OSPM: | remove event | OSPM: |
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| send Eject Request, | | Scan memory devices |
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| clear remove event +<-------------+ for event flags |
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+---------------------+ +-------------------------+
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+---------v--------+ +-----------------------+
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| Guest OS: | success | OSPM: |
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| process Ejection +----------->+ Execute _EJ0 method, |
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| request | | set eject bit in flags|
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+------------------+ +-----------------------+
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|failure |
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v v
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+------------------------+ +-----------------------+
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| OSPM: | | QEMU: |
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| set OST event & status | | call device unplug cb |
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| fields | | |
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+------------------------+ +-----------------------+
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v v
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+------------------+ +-------------------+
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|QEMU: | |QEMU: |
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|Send OST QMP event| |Send device deleted|
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| | |QMP event |
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+------------------+ | |
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+-------------------+
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