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 <bjorn@xxxxxxx> wrote:
Lucas Tanure <tanure@xxxxxxxxx> writes:copy_to_user returns the number of bytes which could *not* be copied.
>> 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 it will return 0 on success, making your read return 0.
Bjørn
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