Computer memory architecture is growing more complex over time, with
different types of memory attached to a CPU via a number of paths. The
kernel development community is duly working to make this memory available
to user space in an equally diverse set of ways. Two sessions at the 2019
Linux Storage, Filesystem, and Memory-Management Summit presented possible
mechanisms and APIs to allow programs to work with the types of memory they
need.

Source: LWN.net – [$] Presenting heterogeneous memory to user space