NFS client support for NFS version 4 (EXPERIMENTAL)

modulename: nfs4.ko

and/or

nfsv4.ko

configname: CONFIG_NFS_V4

Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>NFS client support for NFS version 4 (EXPERIMENTAL)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This option enables support for version 4 of the NFS protocol
(RFC 3530) in the kernel's NFS client.

To mount NFS servers using NFSv4, you also need to install user
space programs which can be found in the Linux nfs-utils package,
available from http://linux-nfs.org/.

If unsure, say N.