How to do it...

Let's see how to do it by following these steps:

1. First, let's define our module parameters, as follows:

static int var = 0x3f;
module_param(var, int, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(var, "an integer value");

static char *str = "default string";
module_param(str, charp, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(str, "a string value");

#define ARR_SIZE 8
static int arr[ARR_SIZE];
static int arr_count;
module_param_array(arr, int, &arr_count, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(arr, "an array of " __stringify(ARR_SIZE) " values");

1. Then, we can use the following init and exit functions:

static int __init module_par_init(void)
{
    int i;

    pr_info("loaded\n");
    pr_info("var = 0x%02x\n", var);
    pr_info("str = \"%s\"\n", str);
    pr_info("arr = ");
    for (i = 0; i < ARR_SIZE; i++)
        pr_cont("%d ", arr[i]);
    pr_cont("\n");

    return 0;
}

static void __exit module_par_exit(void)
{
    pr_info("unloaded\n");
}

module_init(module_par_init);
module_exit(module_par_exit);

1. Finally, at the end, we can add module description macros as usual:

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rodolfo Giometti");
MODULE_DESCRIPTION("Module with parameters");
MODULE_VERSION("0.1");