Build System

Please read the "Kbuild: the Linux Kernel Build System" carefully, you will understand how this system works Kbuild Linux Kernel Build System

Do you want to do another Linux Kernel Build System exercise by writing a Hello World Kernel Module? then keep reading...

Linux Kernel Build System, Hello World Module

Make a "helloworld" directory under drivers

    user@workstation:~/linux$ mkdir drivers/helloworld

Create helloworld.c file under our helloworld directory and add the C code below, this is a simple Hello World Kernel Module

    user@workstation:~/linux$$ nano drivers/helloworld/helloworld.c
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>

static int module_init_function(void)clear

{
    printk(KERN_INFO "Module? Hello!\n");
    return 0;
}

static void module_exit_function(void)
{
    printk(KERN_INFO "Module? Bye!\n");
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("xe1gyq");
MODULE_DESCRIPTION("My First Linux Kernel Module");

module_init(module_init_function);
module_exit(module_exit_function);

Linux Kernel Build System, Hello World Kconfig

Create the Kconfig file under helloworld directory and add the code below, make sure indentation is correct

Linux Kernel Build System, Hello World Makefile

Create the Makefile under helloworld directory and add the code below

Linux Kernel Build System, Device Drivers Kconfig seeing Hello World Directory

Modify Kconfig under drivers directory and add the line with helloworld

Linux Kernel Build System, Device Drivers Makefile compiling Hello World Directory

Modify Makefile under drivers directory and add the line with CONFIG_HELLO_WORLD

Linux Kernel Build System, Hello World Menuconfig

We are ready to view our Hello World Module under menuconfig

Go to its location under

Understand the menu options seen below including their fast paths (one letter invocation)

Get help for the Hello Module Kernel Support using Help function, you should see this

Understand about the following options from Kconfig by googling or looking at other Kconfigs

  • default

  • tristate

  • Depends on

Take a look at the default building state for our Hello World Module and modify Kconfig so you can have it built as default

Linux Kernel Build System, Hello World Compilation

Now compile your Hello World Module both as module and built-in into the Kernel image making sure you boot your system twice to confirm your changes using dmesg command

As Module (M)

Built-In (*)

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