Hello World Linux Device Driver Program

Let's in this post write a hello world Linux device driver

Create a hello.c file with the following content in a new folder

	#include <linux/kernel.h>
	#include <linux/module.h>
	MODULE_LICENSE("GPL");
	static int test_hello_init(void)
	{
	printk(KERN_INFO"%s: In init\n", __func__);
	return 0;
	}
	static void test_hello_exit(void)
	{
	printk(KERN_INFO"%s: In exit\n", __func__);
	}
	module_init(test_hello_init);
	module_exit(test_hello_exit);

view raw hello.c hosted with ❤ by GitHub

Create a Makefile with the following content in the same folder

	obj-m += hello.o
	all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
	clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

view raw Makefile hosted with ❤ by GitHub

Command to create a module: make


Command to load module: insmod hello.ko

When you run this command, function specified in module_init will be executed, to check run "dmesg"

Command to remove module: rmmod hello

When you run this command, function specified in module_exit will be executed, verify it by running "dmesg"


Output: