Miscellany

# If KERNELRELEASE is defined, we've been invoked
from
# the kernel build system and can use its language.
ifneq ($(KERNELRELEASE),)
    obj-m := hello.o
 
# Otherwise we were called directly from the command
# line; invoke the kernel build system.
else
    KERNELDIR ?= /lib/modules/$(shell uname
-r)/build
    PWD := $(shell pwd)
 
default:
    $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
endif