Linux simplest kernel module Hello World Example

Note: If you want to follow this practice, you need to have a functioning arm development Board and a corresponding version of the kernel (if you want to compile and run on a Linux host, please refer to the end of the 1)

1. Create the following file in the driver directory of the corresponding version kernel:

Where the file code is as follows:
/* hello.c */

#include <linux/init.h> #include <linux/module.h>static int hello_init (void) {PRINTK (kern_info "[Init] Can    You feel me?\n "); return 0;} static void Hello_exit (void) {PRINTK (kern_info "[Exit] yes.\n"); Module_init (Hello_init); Module_exit (Hello_exit); Module_author ("Alan Wang <[email protected]>"); Module_license ("GPL"); Module_description ("A Simple Hello World Module"); Module_alias ("A simple Module");

/* Kconfig */

# drivers/alan_test/kconfigmenu "Alan_test Driver" comment "alan_test Driver comment" config alan_test bool "Alan_test s Upport "config Hello tristate" Hello module test "depends on Alan_testendmenu

/* Makefile */

# drivers/alan_test/makefile# Makefile for the alan_testobj-$ (Config_hello) + = hello.o

2. Modify the Kconfig Makefie of the previous level of the directory:

Drivers Kconfig End Endmenu add a row before

SOURCE "Drivers/alan_test/kconfig" Endmenu

Add a line to the end of Makefile under drivers

obj-$ (config_alan_test) + = alan_test/

3. Make Menuconfig Add the newly-written module to the kernel:

In turn: Device drivers-->
Alan_test driver-->
Alan_test Driver Comment * * *
[*] Alan_test Support
< M > Hello module test

Exit Save Menuconfig

4. Compile the kernel:

Compiling with make
The generated zimage (arch/arm/boot/zimage) is burned to the corresponding location of the Development Board.
The generated Hello.ko(Drivers/alan_test/hello.ko) is copied to a directory on the Development Board Linux system.

5. Insert the kernel module:

6. Use Modinfo to view module information:

Modinfo

Attachment 1: Compile the module to run on the PC

Put hello.c and Makefile in the same directory.
/* Makefile */

Kernel_ver = $ (Shell uname-r) # KERNEL Modulesobj-m + = hello.o# Specify flags for the module COMPILATIONEXTRA_CFLAGS = g -o0build:kernel_moduleskernel_modules:make-c/lib/modules/$ (kernel_ver)/build m=$ (CURDIR) modulesclean:make-c/ lib/modules/$ (kernel_ver)/build m=$ (CURDIR) Clean

Compile run steps such as:

Linux simplest kernel module Hello World Example