Commit 014d8fd8 authored by Aishwarya Pant's avatar Aishwarya Pant Committed by Jonathan Corbet

acpi: nfit: document sysfs interface

This is an attempt to document the nfit sysfs interface. The
descriptions have been collected from git commit logs and the ACPI
specification 6.2.
Signed-off-by: default avatarAishwarya Pant <aishpant@gmail.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent bd15134a
For all of the nmem device attributes under nfit/*, see the 'NVDIMM Firmware
Interface Table (NFIT)' section in the ACPI specification
(http://www.uefi.org/specifications) for more details.
What: /sys/bus/nd/devices/nmemX/nfit/serial
Date: Jun, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Serial number of the NVDIMM (non-volatile dual in-line
memory module), assigned by the module vendor.
What: /sys/bus/nd/devices/nmemX/nfit/handle
Date: Apr, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) The address (given by the _ADR object) of the device on its
parent bus of the NVDIMM device containing the NVDIMM region.
What: /sys/bus/nd/devices/nmemX/nfit/device
Date: Apr, 2015
KernelVersion: v4.1
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Device id for the NVDIMM, assigned by the module vendor.
What: /sys/bus/nd/devices/nmemX/nfit/rev_id
Date: Jun, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Revision of the NVDIMM, assigned by the module vendor.
What: /sys/bus/nd/devices/nmemX/nfit/phys_id
Date: Apr, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Handle (i.e., instance number) for the SMBIOS (system
management BIOS) Memory Device structure describing the NVDIMM
containing the NVDIMM region.
What: /sys/bus/nd/devices/nmemX/nfit/flags
Date: Jun, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) The flags in the NFIT memory device sub-structure indicate
the state of the data on the nvdimm relative to its energy
source or last "flush to persistence".
The attribute is a translation of the 'NVDIMM State Flags' field
in section 5.2.25.3 'NVDIMM Region Mapping' Structure of the
ACPI specification 6.2.
The health states are "save_fail", "restore_fail", "flush_fail",
"not_armed", "smart_event", "map_fail" and "smart_notify".
What: /sys/bus/nd/devices/nmemX/nfit/format
What: /sys/bus/nd/devices/nmemX/nfit/format1
What: /sys/bus/nd/devices/nmemX/nfit/formats
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) The interface codes indicate support for persistent memory
mapped directly into system physical address space and / or a
block aperture access mechanism to the NVDIMM media.
The 'formats' attribute displays the number of supported
interfaces.
This layout is compatible with existing libndctl binaries that
only expect one code per-dimm as they will ignore
nmemX/nfit/formats and nmemX/nfit/formatN.
What: /sys/bus/nd/devices/nmemX/nfit/vendor
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Vendor id of the NVDIMM.
What: /sys/bus/nd/devices/nmemX/nfit/dsm_mask
Date: May, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) The bitmask indicates the supported device specific control
functions relative to the NVDIMM command family supported by the
device
What: /sys/bus/nd/devices/nmemX/nfit/family
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Displays the NVDIMM family command sets. Values
0, 1, 2 and 3 correspond to NVDIMM_FAMILY_INTEL,
NVDIMM_FAMILY_HPE1, NVDIMM_FAMILY_HPE2 and NVDIMM_FAMILY_MSFT
respectively.
See the specifications for these command families here:
http://pmem.io/documents/NVDIMM_DSM_Interface-V1.6.pdf
https://github.com/HewlettPackard/hpe-nvm/blob/master/Documentation/
https://msdn.microsoft.com/library/windows/hardware/mt604741"
What: /sys/bus/nd/devices/nmemX/nfit/id
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) ACPI specification 6.2 section 5.2.25.9, defines an
identifier for an NVDIMM, which refelects the id attribute.
What: /sys/bus/nd/devices/nmemX/nfit/subsystem_vendor
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Sub-system vendor id of the NVDIMM non-volatile memory
subsystem controller.
What: /sys/bus/nd/devices/nmemX/nfit/subsystem_rev_id
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Sub-system revision id of the NVDIMM non-volatile memory subsystem
controller, assigned by the non-volatile memory subsystem
controller vendor.
What: /sys/bus/nd/devices/nmemX/nfit/subsystem_device
Date: Apr, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Sub-system device id for the NVDIMM non-volatile memory
subsystem controller, assigned by the non-volatile memory
subsystem controller vendor.
What: /sys/bus/nd/devices/ndbusX/nfit/revision
Date: Jun, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) ACPI NFIT table revision number.
What: /sys/bus/nd/devices/ndbusX/nfit/scrub
Date: Sep, 2016
KernelVersion: v4.9
Contact: linux-nvdimm@lists.01.org
Description:
(RW) This shows the number of full Address Range Scrubs (ARS)
that have been completed since driver load time. Userspace can
wait on this using select/poll etc. A '+' at the end indicates
an ARS is in progress
Writing a value of 1 triggers an ARS scan.
What: /sys/bus/nd/devices/ndbusX/nfit/hw_error_scrub
Date: Sep, 2016
KernelVersion: v4.9
Contact: linux-nvdimm@lists.01.org
Description:
(RW) Provides a way to toggle the behavior between just adding
the address (cache line) where the MCE happened to the poison
list and doing a full scrub. The former (selective insertion of
the address) is done unconditionally.
This attribute can have the following values written to it:
'0': Switch to the default mode where an exception will only
insert the address of the memory error into the poison and
badblocks lists.
'1': Enable a full scrub to happen if an exception for a memory
error is received.
What: /sys/bus/nd/devices/ndbusX/nfit/dsm_mask
Date: Jun, 2017
KernelVersion: v4.13
Contact: linux-nvdimm@lists.01.org
Description:
(RO) The bitmask indicates the supported bus specific control
functions. See the section named 'NVDIMM Root Device _DSMs' in
the ACPI specification.
What: /sys/bus/nd/devices/regionX/nfit/range_index
Date: Jun, 2015
KernelVersion: v4.2
Contact: linux-nvdimm@lists.01.org
Description:
(RO) A unique number provided by the BIOS to identify an address
range. Used by NVDIMM Region Mapping Structure to uniquely refer
to this structure. Value of 0 is reserved and not used as an
index.
What: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size
Date: Aug, 2017
KernelVersion: v4.14
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Size of a write request to a DIMM that will not incur a
read-modify-write cycle at the memory controller.
When the nfit driver initializes it runs an ARS (Address Range
Scrub) operation across every pmem range. Part of that process
involves determining the ARS capabilities of a given address
range. One of the capabilities that is reported is the 'Clear
Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2
section 9.20.7.4 Function Index 1 - Query ARS Capabilities).
This property indicates the boundary at which the NVDIMM may
need to perform read-modify-write cycles to maintain ECC (Error
Correcting Code) blocks.
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