Hi!
Goal, when the user do :
# head -1 /dev/miscdrv
The driver prints: Hello World!
Steps:
# Make
# insmod misc.ko
# head -1 /dev/miscdrv
Why my driver doesn't work ?
What is worg with my read operation?
static ssize_t
misc_drv_read(struct file *filp, char __user * buf, size_t count, loff_t
Lucas Tanure tan...@linux.com writes:
What is worg with my read operation?
static ssize_t
misc_drv_read(struct file *filp, char __user * buf, size_t count, loff_t *
offp){
int nbytes;
char * string = hello World;
nbytes = copy_to_user(buf, string, 12);
return nbytes;
}
So, My misc_drv_read returns 0, and it's ok. So why the command head didn't
get the string ?
--
Lucas Tanure
+55 (19) 988176559
On Tue, May 27, 2014 at 9:59 AM, Bjørn Mork bj...@mork.no wrote:
Lucas Tanure tan...@linux.com writes:
What is worg with my read operation?
static ssize_t
Lucas Tanure tan...@linux.com writes:
So, My misc_drv_read returns 0, and it's ok. So why the command head didn't
get the string ?
You told it that it got a string with length 0. And that's what it printed.
Bjørn
___
Kernelnewbies mailing list
Wow, many thanks.
So the read operation should return the total number of bytes, not a
true/false int.
I need to read more about this operations.
Thanks
--
Lucas Tanure
+55 (19) 988176559
On Tue, May 27, 2014 at 10:05 AM, Bjørn Mork bj...@mork.no wrote:
Lucas Tanure tan...@linux.com writes:
Hi!
On Die, 2014-05-27 at 10:09 -0300, Lucas Tanure wrote:
Wow, many thanks.
So the read operation should return the total number of bytes, not a
true/false int.
The syscall here (done by `head`) is read() ...
I need to read more about this operations.
.. and the drivers .read function is
I think it is good for you to read LDD3 or google some corresponding
materials at first.
2014-05-27 20:48 GMT+08:00 Lucas Tanure tan...@linux.com:
Hi!
Goal, when the user do :
# head -1 /dev/miscdrv
The driver prints: Hello World!
Steps:
# Make
# insmod misc.ko
# head -1 /dev/miscdrv
