On Sat, Sep 25, 2010 at 9:46 PM, Bond <[email protected]> wrote:
>
>
> On Sun, Sep 26, 2010 at 3:43 AM, Venkatram Tummala <[email protected]
> > wrote:
>
>> This will print the the last character of the string you wrote.
>>
> If you would have read the thread from my first post printing the last
> character is not my objective I am trying to print the complete string.
>
Yes, it is possible to pass in 0 for register_chrdev. Please be clear what
you want to achieve, from your subject line & the post. The subject line &
the first few lines of the post indicates that you need something which
prints only the last character. And you go on creating a rucus around here.
I have updated the code & attached it. This can only read & write 10
characters. Now, please dont tell us that it is not you wanted or it doesn't
work. Please spare us.
>
>> As a side note, please spare us all with all this non-sense. We have
>> better things to do in our life. Please try your level best to understand
>> things before asking the kernel mailing list. If this BS continues, i am
>> afraid you will get yourself kicked out of the mailing list. Please do
>> yourself a favour by not posting such crap.
>>
>> Venkatram Tummala
>>
>> Please read the thread before giving a lecture on kernel newbies.
>
>
/* Necessary includes for device drivers */
#include <linux/init.h>
//#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */
#include <linux/slab.h> /* kmalloc() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/types.h> /* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h> /* O_ACCMODE */
#include <asm/system.h> /* cli(), *_flags */
#include <asm/uaccess.h> /* copy_from/to_user */
MODULE_LICENSE("Dual BSD/GPL");
/* Declaration of memory.c functions */
int memory_open(struct inode *inode, struct file *filp);
int memory_release(struct inode *inode, struct file *filp);
ssize_t memory_read(struct file *filp, char *buf, size_t count, loff_t *f_pos);
ssize_t memory_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos);
void memory_exit(void);
int memory_init(void);
/* Structure that declares the usual file */
/* access functions */
struct file_operations memory_fops = {
read: memory_read,
write: memory_write,
open: memory_open,
release: memory_release
};
/* Declaration of the init and exit functions */
module_init(memory_init);
module_exit(memory_exit);
/* Buffer to store data */
char *memory_buffer;
int result;
int memory_init(void) {
/* Registering device */
result = register_chrdev(0, "bond", &memory_fops);
if (result < 0) {
printk(KERN_ALERT "memory: cannot obtain major number \n");
return result;
}
/* Allocating memory for the buffer */
memory_buffer = kmalloc(10, GFP_KERNEL);
if (!memory_buffer) {
result = -ENOMEM;
goto fail;
}
memset(memory_buffer, 0, 10);
printk(KERN_ALERT "Inserting bond module\n");
return 0;
fail:
memory_exit();
return result;
}
void memory_exit(void) {
/* Freeing the major number */
unregister_chrdev(result, "bond");
/* Freeing buffer memory */
if (memory_buffer) {
kfree(memory_buffer);
}
printk( KERN_ALERT "Removing bond module\n");
}
int memory_open(struct inode *inode, struct file *filp) {
/* Success */
return 0;
}
int memory_release(struct inode *inode, struct file *filp) {
/* Success */
return 0;
}
ssize_t memory_read(struct file *filp, char __user *buf,
size_t count, loff_t *f_pos)
{
if (*f_pos > 0)
return 0;
if (count > strlen(memory_buffer))
count = strlen(memory_buffer);
copy_to_user(buf,memory_buffer,count);
*f_pos = *f_pos + count;
return count;
}
ssize_t memory_write( struct file *filp, const char __user *buf,
size_t count, loff_t *f_pos)
{
copy_from_user(memory_buffer, buf, count);
return count;
}
