just to tell you a few steps I followed to NFS (linux) install osmc 2015.06-1 on pi2 using the installer:
The first pi2 boot will work, files will be copied to NFS share as they should
After the reboot, the pi2 will not start. I will stall while trying to access the NFS share (screen will be black). You will need to edit the cmdline.txt of the sd card and set the TCP and vers=3 options to NFS, like this (I also give larger rsize and wsize):
root=/dev/nfs nfsroot=10.11.12.1:/shares/osmc3,vers=3,rsize=1048576,wsize=1048576,tcp ip=dhcp rootwait quiet osmcdev=rbp2
Once you save this and boot pi2 it will continue as it should.
You will not be able to mount other NFS shares at boot (you will be able to mount them by hand later). It seems there is a systemd dependency loop for rpcbind. Systemd reports this:
Job rpcbind.service/stop deleted to break ordering cycle starting with sysinit.target/stop
Also, rpc.rstatd is not installed. You should install it with this:
sudo apt-get install rstatd
To mount an NFS share at boot, I added these to /etc/rc.local
/etc/init.d/rpcbind start /usr/sbin/start-statd mount /your_other_nfs_share
Of course your_other_nfs_share should be present in /etc/fstab.