Merge "Add note and daxio version to the vPMEM document"

Author: Zuul

doc/source/admin/virtual-persistent-memory.rst

@@ -31,12 +31,23 @@ The following are required to support the vPMEM feature:
 
   ``dax_pmem``, ``nd_pmem``, ``device_dax``, ``nd_btt``
 
+.. note::
+
+  NVDIMM support is present in the Linux Kernel v4.0 or newer. It is
+  recommended to use Kernel version 4.2 or later since `NVDIMM support
+  <https://docs.pmem.io/persistent-memory/getting-started-guide/creating-development-environments/linux-environments>`_
+  is enabled by default. We met some bugs in older versions, and we have
+  done all verification works with OpenStack on 4.18 version, so 4.18
+  version and newer will probably guarantee its functionality.
+
 * QEMU version >= 3.1.0
 
 * Libvirt version >= 5.0.0
 
 * `ndctl`_ version >= 62
 
+* daxio version >= 1.6
+
 The vPMEM feature has been verified under the software and hardware listed above.