Build ko outside kernel source tree

Makefile

# Run me as                                                                                                            
# ARCH=arm CROSS_COMPILE=~/buildroot-2016.05/output/host/usr/bin/arm-buildroot-linux-uclibcgnueabi- make               
# If KERNELRELEASE is defined, we've been invoked from the                                                             
# kernel build system and can use its language.                                                                        
ifneq ($(KERNELRELEASE),)                                                                                              
obj-m := kobject.o                                                                                                     
# Otherwise we were called directly from the command                                                                   
# line; invoke the kernel build system.                                                                                
else                                                                                                                   
KERNELDIR ?= ../../output/build/linux-4.5.3/                                                                           
PWD := $(shell pwd)                                                                                                    
default:                                                                                                               
»·······$(MAKE) -C $(KERNELDIR) M=$(PWD) modules                                                                       
endif