This patch adds the libnfsidmap package to buildroot, which
is required for NFSv4.

Index: buildroot/package/Config.in
===================================================================
--- buildroot.orig/package/Config.in	2016-03-01 15:47:30.000000000 -0500
+++ buildroot/package/Config.in	2016-05-23 22:53:39.675616052 -0400
@@ -1098,6 +1098,7 @@
 	source "package/libnetfilter_log/Config.in"
 	source "package/libnetfilter_queue/Config.in"
 	source "package/libnfnetlink/Config.in"
+	source "package/libnfsidmap/Config.in"
 	source "package/libnftnl/Config.in"
 	source "package/libnice/Config.in"
 	source "package/libnl/Config.in"
Index: buildroot/package/libnfsidmap/Config.in
===================================================================
--- /dev/null  1970-01-01 00:00:00.000000000 +0000
+++ buildroot/package/libnfsidmap/Config.in	2016-05-24 14:05:59.464401417 -0400
@@ -0,0 +1,6 @@
+config BR2_PACKAGE_LIBNFSIDMAP
+	bool "libnfsidmap"
+	help
+	  Library used by the NFSv4 server to do userid mapping.
+
+	  http://www.citi.umich.edu/projects/nfsv4/linux/libnfsidmap
Index: buildroot/package/libnfsidmap/libnfsidmap.mk
===================================================================
--- /dev/null  1970-01-01 00:00:00.000000000 +0000
+++ buildroot/package/libnfsidmap/libnfsidmap.mk	2016-05-24 14:07:41.559984998 -0400
@@ -0,0 +1,12 @@
+#
+# libnfsidmap
+#
+
+LIBNFSIDMAP_VERSION = 0.25
+LIBNFSIDMAP_SITE = http://www.citi.umich.edu/projects/nfsv4/linux/libnfsidmap
+LIBNFSIDMAP_SOURCE = libnfsidmap-$(LIBNFSIDMAP_VERSION).tar.gz
+LIBNFSIDMAP_INSTALL_STAGING = YES
+LIBNFSIDMAP_LICENSE = BSD-like
+LIBNFSIDMAP_LICENSE_FILES = COPYING
+
+$(eval $(autotools-package))
Index: buildroot/package/nfs-utils/Config.in
===================================================================
--- buildroot.orig/package/nfs-utils/Config.in	2016-03-01 15:47:30.000000000 -0500
+++ buildroot/package/nfs-utils/Config.in	2016-05-24 14:10:45.008236759 -0400
@@ -1,3 +1,4 @@
+
 comment "nfs-utils needs a toolchain w/ threads"
 	depends on BR2_USE_MMU
 	depends on !BR2_TOOLCHAIN_HAS_THREADS
@@ -34,4 +35,17 @@
 
 endmenu
 
+config BR2_PACKAGE_NFS_UTILS_NFS4
+	bool "NFSv4 support"
+	depends on BR2_PACKAGE_NFS_UTILS
+	select BR2_PACKAGE_LIBEVENT
+	select BR2_PACKAGE_LIBNFSIDMAP
+	help
+	  Support for NFSv4.  Don't forget to enable the kernel facility
+	  also.
+
+
+comment "nfs-utils requires a toolchain with RPC and LARGEFILE support"
+	depends on !BR2_INET_RPC || !BR2_LARGEFILE
+
 endif
Index: buildroot/package/nfs-utils/etc-idmapd.conf
===================================================================
--- /dev/null  1970-01-01 00:00:00.000000000 +0000
+++ buildroot/package/nfs-utils/etc-idmapd.conf	2016-05-24 14:20:15.998907833 -0400
@@ -0,0 +1,8 @@
+[General]
+Verbosity = 0
+Pipefs-Directory = /var/lib/nfs/rpc_pipefs
+Domain = localdomain
+
+[Mapping]
+Nobody-User = nobody
+Nobody-Group = nogroup
Index: buildroot/package/nfs-utils/nfs-utils.mk
===================================================================
--- buildroot.orig/package/nfs-utils/nfs-utils.mk	2016-03-01 15:47:30.000000000 -0500
+++ buildroot/package/nfs-utils/nfs-utils.mk	2016-05-24 14:23:23.223169584 -0400
@@ -15,15 +15,19 @@
 NFS_UTILS_CONF_ENV = knfsd_cv_bsd_signals=no
 
 NFS_UTILS_CONF_OPTS = \
-	--disable-nfsv4 \
-	--disable-nfsv41 \
 	--disable-gss \
 	--disable-uuid \
-	--disable-ipv6 \
 	--without-tcp-wrappers \
 	--with-statedir=/run/nfs \
 	--with-rpcgen=internal
 
+ifeq ($(BR2_PACKAGE_LIBNFSIDMAP),y)
+NFS_UTILS_DEPENDENCIES += libevent libnfsidmap lvm2 sqlite
+NFS_UTILS_CONF_OPTS += --enable-nfsv4 --enable-nfsv41
+else
+NFS_UTILS_CONF_OPTS += --disable-nfsv4 --disable-nfsv41
+endif
+
 NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPCDEBUG) += usr/sbin/rpcdebug
 NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPC_LOCKD) += usr/sbin/rpc.lockd
 NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPC_RQUOTAD) += usr/sbin/rpc.rquotad
@@ -48,7 +52,16 @@
 	$(INSTALL) -D -m 644 \
 		$(@D)/utils/mount/nfsmount.conf $(TARGET_DIR)/etc/nfsmount.conf
 endef
+
+define NFS_UTILS_INSTALL_IDMAPD_CONF
+	$(INSTALL) -m 0644 package/nfs-utils/etc-idmapd.conf \
+		$(TARGET_DIR)/etc/idmapd.conf
+endef
+
 NFS_UTILS_POST_INSTALL_TARGET_HOOKS += NFS_UTILS_INSTALL_FIXUP
+ifeq ($(BR2_PACKAGE_NFS_UTILS_NFS4),y)
+  NFS_UTILS_POST_INSTALL_TARGET_HOOKS += NFS_UTILS_INSTALL_IDMAPD_CONF
+endif
 
 ifeq ($(BR2_INIT_SYSTEMD),y)
 NFS_UTILS_CONF_OPTS += --with-systemd=/usr/lib/systemd/system
Index: buildroot/package/nfs-utils/S60nfs
===================================================================
--- buildroot.orig/package/nfs-utils/S60nfs	2016-03-01 15:47:30.000000000 -0500
+++ buildroot/package/nfs-utils/S60nfs	2016-05-24 14:19:29.510097452 -0400
@@ -3,11 +3,17 @@
 # nfs           This shell script takes care of starting and stopping
 #               the NFS services. Stolen from RedHat FC5.
 
+ENABLEv4=yes
+
 [ -x /usr/sbin/rpc.statd ] || exit 0
 [ -x /usr/sbin/rpc.nfsd ] || exit 0
 [ -x /usr/sbin/rpc.mountd ] || exit 0
 [ -x /usr/sbin/exportfs ] || exit 0
 
+if [ $ENABLEv4 == "yes" ]; then
+	[ -x /usr/sbin/rpc.idmapd ] || exit 0
+fi
+
 mkdir -p /var/lock/subsys
 mkdir -p /run/nfs/sm
 mkdir -p /run/nfs/sm.bak
@@ -20,12 +26,26 @@
     . "${CFG_FILE}"
 fi
 
+if [ $ENABLEv4 == "yes" ]; then
+	pipefs_dir="`sed -n 's/^ *Pipefs-Directory *= *//p' /etc/idmapd.conf`"
+fi
+
 
 start() {
 	# Start daemons.
+	if [ $ENABLEv4 == "yes" ]; then
+	  printf "Starting NFS idmapd: "
+	  [ -d /var/lib/nfs/v4recovery ] || mkdir -p /var/lib/nfs/v4recovery
+	  [ -d "$pipefs_dir" ] || mkdir -p "$pipefs_dir"
+	  if ! ( grep -q "on $pipefs_dir type rpc_pipefs" /proc/mounts ); then
+	    mount -t rpc_pipefs sunrpc "$pipefs_dir"
+	  fi
+	  rpc.idmapd
+	  echo "done"
+	fi
+
 	printf "Starting NFS statd: "
 	rpc.statd
-	touch /var/lock/subsys/nfslock
 	echo "done"
 
 	printf "Starting NFS services: "
@@ -39,11 +59,17 @@
 	printf "Starting NFS mountd: "
 	rpc.mountd
 	echo "done"
-	touch /var/lock/subsys/nfs
 }
 
 stop() {
 	# Stop daemons.
+	if [ $ENABLEv4 == "yes" ]; then
+	  printf "Shutting down NFS idmapd: "
+	  killall -q rpc.idmapd
+	  umount "$pipefs_dir"
+	  echo "done"
+	fi
+
 	printf "Shutting down NFS mountd: "
 	killall -q rpc.mountd
 	echo "done"
@@ -54,14 +80,12 @@
 
 	printf "Shutting down NFS services: "
 	/usr/sbin/exportfs -au
-	rm -f /var/lock/subsys/nfs
 	killall -q rpc.statd
 	echo "done"
 
 	printf "Stopping NFS statd: "
 	killall -q rpc.statd
 	echo "done"
-	rm -f /var/lock/subsys/nfslock
 }
 
 # See how we were called.
@@ -78,7 +102,6 @@
 	;;
   reload)
 	/usr/sbin/exportfs -r
-	touch /var/lock/subsys/nfs
 	;;
   *)
 	echo "Usage: nfs {start|stop|reload}"