kernel2.6 kernel moduleのmake作法

[hirasawa@cent5-64b-40 ~]$ cat Makefile 
obj-m := hello.o

ROOTDIR  := ~/rpmbuild/BUILD/kernel-2.6.18/linux/
PWD   := $(shell pwd)

default:
	$(MAKE) -C $(ROOTDIR) M=$(PWD) modules

clean:
	rm -f *.o *.ko
[hirasawa@cent5-64b-40 ~]$ 

#include <linux/module.h>   // required by all modules
#include <linux/kernel.h>   // required by printk()
#include <linux/init.h>

MODULE_LICENSE("GPL2");
MODULE_DESCRIPTION("hello");
MODULE_AUTHOR("toshi");

// Start/Init function
static int hello_init(void) {
    printk(KERN_ALERT "Hello world!\n");
    return 0;
}

// End/Cleanup function
static void hello_exit(void) {
    printk(KERN_ALERT "Goodbye world!\n");
}

module_init(hello_init);
module_exit(hello_exit);