Linux驅動開發之編寫第一個內核模塊--Hello World

1. 在內核目錄下新建一個目錄如hello_world命令如下:

mkdir hello_world

2. 編寫hello.c文件,源碼如下:

/*
 * a simple kernel module: hello
 *
 * Copyright (C) 2020 xxx (xxxxx)
 *
 * Licensed under GPLv2 or later
 */
#include <linux/init.h>
#include <linux/module.h>

static int __init hello_init(void)
{
        printk(KERN_INFO "hello World enter\n");
        return 0;
}

module_init(hello_init);

static void __exit hello_exit(void)
{
        printk(KERN_INFO "hello World exit\n");
}
module_exit(hello_exit);

MODULE_AUTHOR("xx xx <xxxxx>");//作者
MODULE_LICENSE("GPS v2");//模塊許可證聲明,一般用GPL v2
MODULE_DESCRIPTION("A simple hello world module");//模塊描述
MODULE_ALIAS("a simplest module"); //別名

3. 編寫Makefile

KVERS = $(shell uname -r)

obj-m += hello.o

build: kernel_modules

kernel_modules:
        make -C /lib/modules/$(KVERS)/build M=$(CURDIR) modules

clean:
        make -C /lib/modules/$(KVERS)/build M=$(CURDIR) clean

4. 在hello_world目錄下執行make命令

$ make
make -C /lib/modules/3.10.0Likaige+/build M=/home/LiKaige/kernel/2_linux-3.10/drivers/misc/hello_world modules
make[1]: Entering directory '/home/LiKaige/kernel/2_linux-3.10'
  CC [M]  /home/LiKaige/kernel/2_linux-3.10/drivers/misc/hello_world/hello.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /home/LiKaige/kernel/2_linux-3.10/drivers/misc/hello_world/hello.mod.o
  LD [M]  /home/LiKaige/kernel/2_linux-3.10/drivers/misc/hello_world/hello.ko
make[1]: Leaving directory '/home/LiKaige/kernel/2_linux-3.10'
$ ls *.ko
hello.ko

生成hello.ko文件

5. 常用的幾個命令:

insmod hello.ko        //加載模塊
rmmod hello.ko         //卸載模塊
lsmod | grep hello     //查看模塊是否運行及是否被使用
tail /var/log/messages //查看加載或卸載模塊時內核打印的log
modinfo hello.ko       //查看內核模塊參數,如author, license, description等

注意:以上幾個命令都要用root權限
eg:

# insmod hello.ko 
# lsmod | grep hello
hello                    905  0 
# rmmod hello.ko 
# tail /var/log/messages
May 25 11:40:37 localhost kernel: hello World exit
May 25 11:40:43 localhost kernel: [  797.016662] hello World enter
May 25 11:40:43 localhost kernel: hello World enter
May 25 11:40:50 localhost journal: No devices in use, exit
May 25 11:40:58 localhost kernel: [  812.600537] hello World exit
May 25 11:40:58 localhost kernel: hello World exit
May 25 11:41:08 localhost kernel: [  821.954504] hello World enter
May 25 11:41:08 localhost kernel: hello World enter
May 25 11:41:10 localhost kernel: [  824.025106] hello World exit
May 25 11:41:10 localhost kernel: hello World exit

對應完整源碼下載鏈接:
https://download.csdn.net/download/sinat_29891353/12456897