params.c

/*
 * params.c - Demonstrates command line argument passing to a module.
 * $insmod params.ko myshort=5 myint=100 mystring="Sohaib" myintArray=3,7
 * .
 * $cat /sys/module/params/parameters/myint
 */

#include <linux/module.h>
//#include <linux/moduleparam.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sohaib <xunilams@gmail.com>");

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;			// array conuter

/*
 * 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); 		// charp = a character pointer
MODULE_PARM_DESC 	(mystring, "A character string");

/*
 * module_param_array(name, type, num, perm);
 * 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 hello_init(void)
{
	int i;
	pr_cont("params.ko: module loaded!");
	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 hello_exit(void)
{
	pr_err("Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);