28.4. Configuring Persistent Memory for use in Device DAX mode

Device DAX (devdax) provides a means for applications to directly access storage, without the involvement of a file system. The benefit of device DAX is that it provides a guaranteed fault granularity, which can be configured using the --align option with the ndctl utility:

ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --align=2M

# ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --align=2M

The given command ensures that the operating system would fault in 2MiB pages at a time. For the Intel 64 and AMD64 architecture, the following fault granularities are supported:

Device DAX nodes (/dev/daxN.M) only supports the following system call:

read() and write() variants are not supported because the use case is tied to persistent memory programming.