insmod module param : invalid parameters

Question

I'm developping sample kernel module driver.ko. I want to specify the block size of data_node structure with module parameter BlockSize. when I run insmod driver.ko alone, it works, but when I specify BlockSize insmod driver.ko BlockSize = 10 I get this eror :

Error: could not insert module driver.ko: Invalid parameters

modinfo -p ./driver.ko command give me this :

BlockSize: size of  buffer (int)

driver.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/kdev_t.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/slab.h>


/* parametter  */
static int BlockNumber = 8;
static int BlockSize = 512;

 module_param( variable name, type, permission);  */

module_param(BlockSize, int, S_IRUGO);
MODULE_PARM_DESC(BlockSize , " size of  buffer");

/* using 'k' as magic number  */
#define SAMPLE_IOC_MAGIC 'k'
#define SAMPLE_IOCRESET _IOWR(SAMPLE_IOC_MAGIC, 0, int)
#define SAMPLE_IOC_MAXNR 0


struct cdev* my_cdev;
dev_t dev;

static int size_to_read;


/* Macro used to compute the minimum */
#define MIN(a,b) (((a) < (b)) ? (a) : (b))





/* data buffer structure */
typedef struct dnode
{
    int bufSize;
    char *buffer;
    struct dnode *next;
} data_node;


/* liste stucture */
typedef struct  lnode
{
    data_node *head;
    data_node *cur_write_node;
    data_node *cur_read_node;   
        int cur_read_offset;
        int cur_write_offset;
    }liste;


   code ..........................

..

It shouldn't be hard to find an example of doing this, both code and command line. As a wild guess since I haven't looked at this in a while, have your tried it without spaces, ie, `insmod driver.ko BlockSize=10` ? — Chris Stratton, Aug 08 '14 at 17:32
@ChrisStratton thanks a lot, it works without space :) I didnt notice that — , Aug 08 '14 at 17:44

score 0 · Accepted Answer · answered Aug 08 '14 at 17:52

It appears that module parameters should be passed without a space between the name and value, ie you should use:

insmod driver.ko BlockSize=10

This makes some sense, as in the command line to insmod itself "BlockSize=10" is a single entry in *argv[] which can be handed off to the kernel as a chunk, while "BlockSize = 10" would be three distinct entries ("BlockSize", "=", "10") which someone would have to write code to re-join.

insmod module param : invalid parameters

1 Answers1