Linux驱动开发之编写第一个内核模块--Hello World

冷不防 2023-02-12 07:24 13阅读 0赞

## 1. 在内核目录下新建一个目录如hello\_world命令如下: ##

mkdir hello_world

## 2. 编写hello.c文件,源码如下: ##

/*
     * 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");//模块许可证声明,一般用GPL v2
    MODULE_DESCRIPTION("A simple hello world module");//模块描述
    MODULE_ALIAS("a simplest module"); //别名

## 3. 编写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目录下执行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. 常用的几个命令: ##

insmod hello.ko        //加载模块
    rmmod hello.ko         //卸载模块
    lsmod | grep hello     //查看模块是否运行及是否被使用
    tail /var/log/messages //查看加载或卸载模块时内核打印的log
    modinfo hello.ko       //查看内核模块参数,如author, license, description等

注意:以上几个命令都要用root权限  
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

对应完整源码下载链接:  
[https://download.csdn.net/download/sinat\_29891353/12456897][https_download.csdn.net_download_sinat_29891353_12456897]

[https_download.csdn.net_download_sinat_29891353_12456897]: https://download.csdn.net/download/sinat_29891353/12456897