if
arm-none-eabi-gdb: error while loading shared libraries: libncurses.so.5: cannot open shared object file: No such file or directory
then
ln -sf libncursesw.so.5.9 libncurses.so.5

arm-none-eabi-gdb: error while loading shared libraries: libncurses.so.5: wrong ELF class: ELFCLASS64

It means that the 32-bit ABI variant of ncurses library is needed: 

sudo apt-get install lib32ncurses5

Allow Users Access to USB Devices

By default, only the superuser has access to USB devices. Change things so that you have access to the F4 Discovery USB STLINK device:

Create a new udev rule in /etc/udev/rules/45-usb-stlink-v2.rules:
SUBSYSTEM=="usb", ATTR{idVendor}=="0483", ATTR{idProduct}=="3748", MODE="0666"

CMAKE_FORCE_C_COMPILER(arm-none-eabi-gcc -mtune=cortex-m3 -mcpu=cortex-m3 -march=armv7-m GNU)