Makefile

# If KERNELRELEASE is defined, we've been invoked from the kernel build system
# and can use its language.
ifneq ($(KERNELRELEASE),)
    $(info [i]: KERNELRELEASE is set == $(KERNELRELEASE))
    # A makefile symbol used by the kernel build system to determine which
    # modules should be built in the current directory.
    obj-m := pepe.o

    ccflags-y := -std=gnu11 -DDEBUG
    pepe-objs := main.o

# Otherwise we were called directly from the command line; invoke the kernel
# build system.
else
    $(info [i]: KERNELRELEASE is not set)
    KERNELDIR ?= /lib/modules/$(shell uname -r)/build
    $(info [i]: KERNELDIR == $(KERNELDIR))
    PWD := $(shell pwd)
    $(info [i]: PWD == $(PWD))

.PHONY: modules
modules:
	$(info [i]: modules)
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

.PHONY: clean
clean:
	$(info [i]: clean)
	rm -rf *.o *.ko *.order *.symvers *.mod *.mod.c

endif