[Linux] [kernel module] How to pass parameters as arguments when loading a loadable kernel module

How to allow parameters to be passed during insmod of loadable kernel module notes Basically you can use module_param (3).

Please refer to the following for how to build the kernel module.

[Linux] [kernel module] Build and load a simple loadable kernel module-Qiita

Source

testmod.c

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

MODULE_LICENSE("MIT");

static int param1 = 1;
static int param2 = 2;

module_param(param1, int, S_IRUGO);
module_param(param2, int, S_IRUGO);

static int testmod_init(void)
{
	printk(KERN_INFO "driver loaded\n");
	printk(KERN_INFO "param1 = %d\n", param1);
	printk(KERN_INFO "param2 = %d\n", param2);
	return 0;
}

static void testmod_exit(void)
{
	printk(KERN_INFO "driver unloaded\n");
}

module_init(testmod_init);
module_exit(testmod_exit);

About module_param (3)

Do something like module_param (param1, int, S_IRUGO);.

• Variable name as the first argument
• Type name in the second argument
• The third argument is a read-only attribute. Permission to change route parameters with S_IRUGO | S_IWUSR.

About the types that can be used

• bool
• invbool
• charp
• int
• long
• short
• uint
• ulong
• ushort

Array parameters (module_param_array (4))

There is also a module_param_array (4) that can handle array parameters. TODO: Sample creation

Execution example

Execution example (no parameters)

$ sudo insmod testmod.ko
$ sudo rmmod testmod.ko
$ dmesg | tail
[109428.165469] driver loaded
[109428.165472] param1 = 1
[109428.165474] param2 = 2
[109428.173077] driver unloaded

Execution example (with parameters)

$ sudo insmod testmod.ko param1=10 param2=20
$ sudo rmmod testmod.ko
$ dmesg | tail
[109428.165469] driver loaded
[109428.165472] param1 = 10
[109428.165474] param2 = 20
[109428.173077] driver unloaded

Relation

[Linux] [kernel module] Build and load a simple loadable kernel module-Qiita

reference

"Linux Device Driver 3rd Edition" 2.8 Module Parameters p.35