| Dan Williams | d4dd709 | 2018-06-03 12:49:15 -0700 | [diff] [blame] | 1 | What: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size |
| 2 | Date: Aug, 2017 |
| 3 | KernelVersion: v4.14 (Removed v4.18) |
| 4 | Contact: linux-nvdimm@lists.01.org |
| 5 | Description: |
| 6 | (RO) Size of a write request to a DIMM that will not incur a |
| 7 | read-modify-write cycle at the memory controller. |
| 8 | |
| 9 | When the nfit driver initializes it runs an ARS (Address Range |
| 10 | Scrub) operation across every pmem range. Part of that process |
| 11 | involves determining the ARS capabilities of a given address |
| 12 | range. One of the capabilities that is reported is the 'Clear |
| 13 | Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2 |
| 14 | section 9.20.7.4 Function Index 1 - Query ARS Capabilities). |
| 15 | This property indicates the boundary at which the NVDIMM may |
| 16 | need to perform read-modify-write cycles to maintain ECC (Error |
| 17 | Correcting Code) blocks. |
