Device memory (pmem, HMM, etc...) hotplug support

modulename: memremap.ko

configname: CONFIG_ZONE_DEVICE

Linux Kernel Configuration
└─>Memory Management options
└─>Device memory (pmem, HMM, etc...) hotplug support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Device memory hotplug support allows for establishing pmem,
or other device driver discovered memory regions, in the
memmap. This allows pfn_to_page() lookups of otherwise
"device-physical" addresses which is needed for using a DAX
mapping in an O_DIRECT operation, among other things.

If FS_DAX is enabled, then say Y.

source code: