Linux内核模块-实例2（二)

2.2 Hello World (P2) :许可权限和模块的声明环境：Linux内核 2.6
1. 内核模块实例（book.c）

/*
  * book.c - Demonstrates module documentation.
  */

# include <linux/module.h> /* Need by all modules */
# include <linux/kernel.h> /* Need for HERN_INFO */
# include <linux/init.h>   /* Need for the macros */

# define DRIVER_AUTHOR "Star <s@dirac.org>"
# define DRIVER_DESC "A sample driver"

  static char* bookName = "Good Book.";
  static int bookNumber = 100;

  static int __init book_init(void)
{
      printk(KERN_INFO "Book name is %s\n", bookName);
      printk(KERN_INFO "Book number is %d\n", bookNumber);

      return 0;
}

  static void __exit book_exit(void)
{
       printk(KERN_INFO "Book module exit.\n");
}

module_init(book_init);
module_exit(book_exit);

module_param(bookName, charp, S_IRUGO);
module_param(bookNumber, int, S_IRUGO);

/*
   You can use strings, like this:
*/
/*
   Get rid of taint message by declaring code as GPL.
  */

MODULE_LICENSE("GPL");

/*
   Or with defines, like this:
*/
MODULE_AUTHOR(DRIVER_AUTHOR);  /* Who wrote this module? */
MODULE_DESCRIPTION(DRIVER_DESC); /* What does this module do */

2.代码解析

MODULE_LICENSE("GPL");

此处可有可无，可以不加，系统默认（但会报警）。模块声明描述内核模块的许可权限，如果不声明LICENSE,模块被加载时，将收到内核的警告。在 Linux2.6 内核中，可接受的 LICENSE 包括＂ GPL","GPL v2","GPL and additional rights","Dual BSD/GPL","Dual MPL/GPL","Proprietary" 。

MODULE_AUTHOR(DRIVER_AUTHOR);MODULE_DESCRIPTION(DRIVER_DESC);

模块的声明与描述可加可不加。
3.Makefile文件的写法

Makefile 文件由五部分组成：显示规则含规则变量定义 makefile 指示符和注释

一条 Make 的规则原型为：

目标 ... ：依赖 ..

命令
代码：参照2.1
相关链接：内核模块编程入门：http://www.tldp.org/LDP/lkmpg/2.6/html/index.html

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Linux内核模块-实例2（二)

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