I am using Cyclone V from Terasic Soc kit and now trying to make driver for Hps to FPGA bridge. I have Quartus and SOCEDS 15.0. I have started with Workshop 3 from rocketboard. https://rocketboards.org/foswiki/view/documentation/ws3developingdriversforalterasoclinux So, I download image, set ENVIRONMENT variable. After that I try to execute first example which is lab_module. So basically I create KBUILD file, make file and after that While, I am trying to executete Make file I got error: makefile:2 *** OUT_DIR is undefined, bad environment. you point OUT_DIR to the linux kernel build ouutput Directory & stop.(PFA) Basically I am not able to execute make and it seems to be compilation error, and I am not able to build the kernel module. I already cross check environmental variable, its: export ARCH=arm; (for ARM achitecture) export CROSS_COMPILE= <path-to>/toolchain/arm-linux-gnueabihf (cross compiler toolchain) export OUT_DIR=<path-to>/socfpga-3.10-ltsi (linux kernel source tree) Could any one help me to solve this?