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.