The following commands were completed on Centos 7.1

Install TFTP

yum -y install tftp tftp-server xinetd

Enable Service

vi /etc/xinetd.d/tftp

change

server_args             = -s /var/lib/tftpboot
disable                 = yes

to

server_args             = -c -s /var/lib/tftpboot
disable                 = no

Elsewhere I see that this is required but I have not had to do so.

chmod 777 /var/lib/tftpboot

reboot

systemctl enable xinetd
systemctl start xinetd