在linux-sdk树外构建模块

CONFIG_MODULE_SIG=n

PWD = $(shell pwd)

obj-m := hello.o

KERNELDIR ?= /home/xxx/rk39_sdk/orangepi-build/kernel/orange-pi-5.18

all default: modules

install: modules_install

modules modules_install help clean:

    $(MAKE) -C $(KERNELDIR) M=$(PWD) $@