TFTP Setup
Next, you have to configure TFTP. To enable it, simply edit your /etc/inetd.conf file and uncomment the tftp line.
tftp	dgram	udp	wait	root	/usr/libexec/tftpd	tftpd -l -s /tftpboot
At the end of the line, change /tftpboot to /usr/nfsroot. The finished line should look like this:
tftp	dgram	udp	wait	root	/usr/libexec/tftpd	tftpd -l -s /usr/nfsroot
You'll have to start (or restart) inetd for the changes to take effect.

Under FreeBSD 6.x you would type:

/etc/rc.d/inetd restart

Note: If you don't have inetd_enable="YES" in your /etc/rc.conf, then you will have to use forcestart instead. Like this:

/etc/rc.d/inetd forcestart