1) Chamge compiler Paths in Makefile

2) build the librairies:

make COMP=gcc TARGET=STM32F769NIHx clean all
make COMP=gcc TARGET=STM32F429ZITx clean all
make COMP=gcc TARGET=STM32F091RCTx clean all
make COMP=gcc TARGET=STM32L152RETx clean all

3) try "hello world"
make flash
make execute