check_linux_kernel_version_make

Makefile

# In Makefile, check if the current kernel version is < 5.6, 
# it sets `ADD_CCFLAGS_Y=-DOLD_KERNEL_FOR_PIN`

# Kernel Version
KVER := $(shell uname -r)
KMAJ := $(shell echo $(KVER) | \
sed -e 's/^\([0-9][0-9]*\)\.[0-9][0-9]*\.[0-9][0-9]*.*/\1/')
KMIN := $(shell echo $(KVER) | \
sed -e 's/^[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*.*/\1/')

# No Indentation Tabs/Spaces in the following ifeq lines please
ifeq ($(shell if [ 5 -gt $(KMAJ) ] ; then echo $$? ; fi ;),0)
$(eval ADD_CCFLAGS_Y=-DOLD_KERNEL_FOR_PIN)
endif 
ifeq ($(shell if [ $(KMAJ) -eq 5 ] && [ 6 -ge $(KMIN) ] ; then echo $$? ; fi ;),0)
$(eval ADD_CCFLAGS_Y=-DOLD_KERNEL_FOR_PIN)
endif