torvalds/linux

What:        /sys/bus/nd/devices/regionX/nfit/ecc_unit_size
Date:        Aug, 2017
KernelVersion:    v4.14 (Removed v4.18)
Contact:    nvdimm@lists.linux.dev
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.