Linux内核模块-实例3（二）

2.3  Hello World（P3）：命令行参数传递
环境：Linux内核 2.6 

1.示例代码（hello-2.c）

/*
* hello-2.c - Demonstrates command line argument passing to a module.
*/

# include <linux/module.h>
# include <linux/moduleparam.h>
# include <linux/kernel.h>
# include <linux/init.h>
# include <linux/stat.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Star");

static short int myshort = 1;
static int myint = 420;
static long int  mylong = 9999;
static char *myString = "blah";
static int myintArray[2] = {-1, -1};
static int arr_argc = 0;

/*
* module_param(foo, int, 0000)
* The first param is the parameters name
* The second param is it's data type
* The final argument is the permissions bits,
* for exposing parameters in sysfs(if non-zero) at a later stage.
*/

module_param(myshort, short, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
MODULE_PARM_DESC(myshort, "A short integer");
module_param(myint, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
MODULE_PARM_DESC(myint, "An integer");
module_param(mylong, long, S_IRUSR);
MODULE_PARM_DESC(mylong, "A long integer");
module_param(myString, charp, 0000);
MODULE_PARM_DESC(myString, "A character string");

/*
* module_param_array(name, type, num, per)
* The first param is the parameter's (in this case the array's) name
* The second param is the data type of the elements of the array
* The third argument is a pointer to the variable that will store the number
* of elements of the array initialized by the user at module loading time
* The fourth argument is the permission bits
*/

module_param_array(myintArray, int, &arr_argc, 0000);
MODULE_PARM_DESC(myintArray, "An array of integers");

static int __init hello_2_init(void)
{
int i;
printk(KERN_INFO "Hello, world 2\n=============\n");
printk(KERN_INFO "myshort is a short integer: %hd\n", myshort);
printk(KERN_INFO "myint is an integer: %d\n", myint);
printk(KERN_INFO "mylong is a long integer: %ld\n", mylong);
printk(KERN_INFO "myString is a string: %s\n", myString);
for(i=0; i < (sizeof myintArray / sizeof(int)) ; i++)
{
printk(KERN_INFO "myintArray[%d] = %d\n", i, myintArray[i]);
}
printk(KERN_INFO "got %d arguments for myintArray.\n", arr_argc);
return 0;
}

static void __exit hello_2_exit(void)
{
printk(KERN_INFO "Goodbye, world 2\n");
}

module_init(hello_2_init);
module_exit(hello_2_exit);

2.运行过程
首先创建Makefile文件(参照2.1中Makefile的创建过程)，然后装载卸载模块。
[root@localhost test]# insmod hello-2.ko myint=2014 myString="welcome" myintArray=4,5

[root@localhost test]# rmmod hello-2.ko
[root@localhost test]# dmesg | tail -10

Hello, world 2

=============

myshort is a short integer: 1

myint is an integer: 2014

mylong is a long integer: 9999

myString is a string: welcome

myintArray[0] = 4

myintArray[1] = 5

got 2 arguments for myintArray.

Goodbye, world 2

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