This program used for copy primary framebuffer to secondary framebuffer (eg. FBTFT). It require lastest raspberry pi firmware (> 2013-07-11) to working properly.
2017-11-29-raspbian-stretch
cmake
$ sudo apt-get install cmake
$ mkdir build
$ cd build
$ cmake ..
$ make
$ ./fbcp
$ sudo cp fbcp /usr/bin $ sudo chmod +x /usr/bin/fbcp $ sudo nano /etc/rc.local -> add new line before "exit 0" with "/usr/bin/fbcp &" without quote $ sudo reboot