162306a36Sopenharmony_ciWhat: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size 262306a36Sopenharmony_ciDate: Aug, 2017 362306a36Sopenharmony_ciKernelVersion: v4.14 (Removed v4.18) 462306a36Sopenharmony_ciContact: nvdimm@lists.linux.dev 562306a36Sopenharmony_ciDescription: 662306a36Sopenharmony_ci (RO) Size of a write request to a DIMM that will not incur a 762306a36Sopenharmony_ci read-modify-write cycle at the memory controller. 862306a36Sopenharmony_ci 962306a36Sopenharmony_ci When the nfit driver initializes it runs an ARS (Address Range 1062306a36Sopenharmony_ci Scrub) operation across every pmem range. Part of that process 1162306a36Sopenharmony_ci involves determining the ARS capabilities of a given address 1262306a36Sopenharmony_ci range. One of the capabilities that is reported is the 'Clear 1362306a36Sopenharmony_ci Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2 1462306a36Sopenharmony_ci section 9.20.7.4 Function Index 1 - Query ARS Capabilities). 1562306a36Sopenharmony_ci This property indicates the boundary at which the NVDIMM may 1662306a36Sopenharmony_ci need to perform read-modify-write cycles to maintain ECC (Error 1762306a36Sopenharmony_ci Correcting Code) blocks. 18