linux_dsm_epyc7002/Documentation/ABI/removed/sysfs-bus-nfit
Dan Williams d4dd70915e acpi, nfit: Remove ecc_unit_size
The "Clear Error Unit" may be smaller than the ECC unit size on some
devices. For example, poison may be tracked at 64-byte alignment even
though the ECC unit is larger. Unless / until the ACPI specification
provides a non-ambiguous way to communicate this property do not expose
this to userspace.

Software that had been using this property must already be prepared for
the case where the property is not provided on older kernels, so it is
safe to remove this attribute.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-06-03 12:49:15 -07:00

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What: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size
Date: Aug, 2017
KernelVersion: v4.14 (Removed v4.18)
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.