NDCTL User Guide

Introduction

ndctl is a utility for managing the Linux LIBNVDIMM Kernel subsystem. It is designed to work with various non-volatile memory devices (NVDIMMs) from different vendors. The LIBNVDIMM subsystem defines a kernel device model and control message interface for platform NVDIMM resources like those defined by the ACPI v6.0 NFIT (NVDIMM Firmware Interface Table). The latest ACPI and UEFI specifications can be found at uefi.org. Operations supported by ndctl include:

• Provisioning capacity (namespaces)

• Enumerating Devices

• Enabling and Disabling NVDIMMs, Regions, and Namespaces

• Managing NVDIMM Labels

What's new in v66

This release incorporates functionality up to the 5.3 kernel, and adds a number of bug fixes, and improvements.

Highlights include a new command to reconfigure dax devices to different modes (devdax - default, and system-ram - to hotplug the dax device as system memory), improvements to ndctl-{read,write,init}-labels allowing smaller sized reads/writes, usability fixes to ndctl-monitor, and ndctl-create-namespace, and a fix to ndctl-check-namespace allowing it to be used on systems with different page sizes.

Commands:

• daxctl-reconfigure-device: new command for device mode management

• daxctl-online-memory, daxctl-offline-memory: new commands for devices in system-ram mode

• monitor: logging improvements, allow sending to background

• inject-error: refuse to operate on active BTT namespaces

• read-labels, write-labels, zero-labels: improvements to minimize data transfer

• create-namespace: usability improvements around region search

APIs:

• ndctl_cmd_cfg_read_set_extent

• ndctl_cmd_cfg_write_set_extent

• ndctl_dimm_read_label_extent

• ndctl_dimm_read_label_index

• ndctl_dimm_zero_label_extent

• daxctl_dev_disable

• daxctl_dev_enable_devdax

• daxctl_dev_enable_ram

• daxctl_dev_get_ctx

• daxctl_dev_get_memory

• daxctl_dev_get_resource

• daxctl_dev_get_target_node

• daxctl_dev_is_enabled

• daxctl_memory_get_block_size

• daxctl_memory_get_dev

• daxctl_memory_get_node_path

• daxctl_memory_is_online

• daxctl_memory_num_sections

• daxctl_memory_offline

• daxctl_memory_online