1*4882a593SmuzhiyunWhat: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size 2*4882a593SmuzhiyunDate: Aug, 2017 3*4882a593SmuzhiyunKernelVersion: v4.14 (Removed v4.18) 4*4882a593SmuzhiyunContact: linux-nvdimm@lists.01.org 5*4882a593SmuzhiyunDescription: 6*4882a593Smuzhiyun (RO) Size of a write request to a DIMM that will not incur a 7*4882a593Smuzhiyun read-modify-write cycle at the memory controller. 8*4882a593Smuzhiyun 9*4882a593Smuzhiyun When the nfit driver initializes it runs an ARS (Address Range 10*4882a593Smuzhiyun Scrub) operation across every pmem range. Part of that process 11*4882a593Smuzhiyun involves determining the ARS capabilities of a given address 12*4882a593Smuzhiyun range. One of the capabilities that is reported is the 'Clear 13*4882a593Smuzhiyun Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2 14*4882a593Smuzhiyun section 9.20.7.4 Function Index 1 - Query ARS Capabilities). 15*4882a593Smuzhiyun This property indicates the boundary at which the NVDIMM may 16*4882a593Smuzhiyun need to perform read-modify-write cycles to maintain ECC (Error 17*4882a593Smuzhiyun Correcting Code) blocks. 18