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Subject[ACPIHP PATCH part1 0/4] introduce a framework for ACPI based system device hotplug
Modern high-end servers may support advanced RAS features, such as
system device dynamic reconfiguration. On x86 and IA64 platforms,
system device means processor(CPU), memory device, PCI host bridge
and even computer node.

The ACPI specifications have provided standard interfaces between
firmware and OS to support device dynamic reconfiguraiton at runtime.
This patch series introduces a new framework for system device
dynamic reconfiguration based on ACPI specification, which will
replace current existing system device hotplug logic embedded in
ACPI processor/memory/container device drivers.

The new ACPI based hotplug framework is modelled after the PCI hotplug
architecture and target to achieve following goals:
1) Optimize device configuration order to achieve best performance for
hot-added system devices. For best perforamnce, system device should
be configured in order of memory -> CPU -> IOAPIC/IOMMU -> PCI HB.
2) Resolve dependencies among hotplug slots. You need first to remove
the memory device before removing a physical processor if a
hotpluggable memory device is connected to a hotpluggable physical
3) Provide interface to cancel ongoing hotplug operations. It may take
a very long time to remove a memory device, so provide interface to
cancel the inprogress hotplug operations.
4) Support new advanced RAS features, such as socket/memory migration.
5) Provide better user interfaces to access the hotplug functionalities.
6) Provide a mechanism to detect hotplug slots by checking existence
of ACPI _EJ0 method or by other hardware platform specific methods.
7) Unify the way to enumerate ACPI based hotplug slots. All hotplug
slots will be enumerated by the enumeration driver (acpihp_slot),
instead of by individual ACPI device drivers.
8) Unify the way to handle ACPI hotplug events. All ACPI hotplug events
for system devices will be handled by a generic ACPI hotplug driver
(acpihp_drv) instead of by individual ACPI device drivers.
9) Provide better error handling and error recovery.
10) Trigger hotplug events/operations by software. This feature is useful
for hardware fault management and/or power saving.

The new framework is composed up of three major components:
1) A system device hotplug slot enumerator driver, which enumerates
hotplug slots in the system and provides platform specific methods
to control those slots.
2) A system device hotplug driver, which is a platform independent
driver to manage all hotplug slots created by the slot enumerator.
The hotplug driver implements a state machine for hotplug slots and
provides user interfaces to manage hotplug slots.
3) Several ACPI device drivers to configure/unconfigure system devices
at runtime.

And the whole patchset will be split into 7 parts:
1) the hotplug slot enumeration driver (acpihp_slot)
2) the system device hotplug driver (acpihp_drv)
3) enhance ACPI container driver to support new framework
4) enhance ACPI processor driver to support new framework
5) enhance ACPI memory driver to support new framework
6) enhance ACPI host bridge driver to support new framework
7) enhancments and cleanups to the ACPI core

This is the first part of hotplug slot enumeration driver (acpihp_slot).
And you may pull from: acpihp_slot

On loading, it will scan ACPI hotplug slots for system device hotplug.
For example, Intel Emerald Ridge/Quantum S4R platform has
1) 4 hotpluggable physical processors
2) 8 hotpluggable memory boards (each processor has two memory boards)
3) 1 hotpluggable IOH and 1 non-hotpluggable legacy IOH

#modprobe acpihp_slot
#cd /sys/bus/acpi/slots
#ls -l
total 0
lrwxrwxrwx CPU00 -> ../../../devices/LNXSYSTM:00/acpihp/CPU00
lrwxrwxrwx CPU01 -> ../../../devices/LNXSYSTM:00/acpihp/CPU01
lrwxrwxrwx CPU02 -> ../../../devices/LNXSYSTM:00/acpihp/CPU02
lrwxrwxrwx CPU03 -> ../../../devices/LNXSYSTM:00/acpihp/CPU03
lrwxrwxrwx IOX01 -> ../../../devices/LNXSYSTM:00/acpihp/IOX01
lrwxrwxrwx MEM00 -> ../../../devices/LNXSYSTM:00/acpihp/CPU00/MEM00
lrwxrwxrwx MEM01 -> ../../../devices/LNXSYSTM:00/acpihp/CPU00/MEM01
lrwxrwxrwx MEM02 -> ../../../devices/LNXSYSTM:00/acpihp/CPU01/MEM02
lrwxrwxrwx MEM03 -> ../../../devices/LNXSYSTM:00/acpihp/CPU01/MEM03
lrwxrwxrwx MEM04 -> ../../../devices/LNXSYSTM:00/acpihp/CPU02/MEM04
lrwxrwxrwx MEM05 -> ../../../devices/LNXSYSTM:00/acpihp/CPU02/MEM05
lrwxrwxrwx MEM06 -> ../../../devices/LNXSYSTM:00/acpihp/CPU03/MEM06
lrwxrwxrwx MEM07 -> ../../../devices/LNXSYSTM:00/acpihp/CPU03/MEM07

For each hotplug slots, it provides following sysfs interfaces:
# cd CPU00/
# ls ; MEM00, MEM01 are child hotplug slots
MEM00 MEM01 capabilities device object power state status subsystem uevent
# cat capabilities ; show slot RAS capabilities
# cat object ; show ACPI object corresponding to this slot
# cat state ; show slot state machine state
# cat status ; show devie health status

Jiang Liu (4):
ACPIHP: introduce a framework for ACPI based system device hotplug
ACPIHP: introduce acpihp_slot driver to enumerate hotplug slots
ACPIHP: detect ACPI hotplug slots by checking ACPI _EJ0 method
ACPIHP: implement a fake ACPI system device hotplug slot enumerator

drivers/acpi/Kconfig | 42 +++
drivers/acpi/Makefile | 2 +
drivers/acpi/hotplug/Makefile | 11 +
drivers/acpi/hotplug/acpihp.h | 36 +++
drivers/acpi/hotplug/core.c | 543 ++++++++++++++++++++++++++++++++++++++
drivers/acpi/hotplug/slot.c | 421 +++++++++++++++++++++++++++++
drivers/acpi/hotplug/slot_ej0.c | 143 ++++++++++
drivers/acpi/hotplug/slot_fake.c | 180 +++++++++++++
include/acpi/acpi_hotplug.h | 208 +++++++++++++++
9 files changed, 1586 insertions(+)
create mode 100644 drivers/acpi/hotplug/Makefile
create mode 100644 drivers/acpi/hotplug/acpihp.h
create mode 100644 drivers/acpi/hotplug/core.c
create mode 100644 drivers/acpi/hotplug/slot.c
create mode 100644 drivers/acpi/hotplug/slot_ej0.c
create mode 100644 drivers/acpi/hotplug/slot_fake.c
create mode 100644 include/acpi/acpi_hotplug.h


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