programming Linux Kernel modules

programming Linux Kernel modules

January 20, 2024

Linux kernel modules run in a priviledged space. But what does this mean? Let's find out.

First let's program a "hello world" Linux kernel module:

create a folder kernel

mkdir kernel

create a file hello.c:

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

MODULE_DESCRIPTION("Insert description");
MODULE_AUTHOR("Insert author");
MODULE_LICENSE("GPL");

static int __init hello_init(void)
{
	printk(KERN_INFO "Hello world\n");
	return 0;
}

module_init(hello_init);

create a file Makefile:

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

run make:

make

insert the module:

sudo insmod hello.ko

verify the syslog:

sudo dmesg

and I see in it the following line that confirms me it works:

[49694.489768] Hello world

See also

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