May 27, 2014
1:03 p.m.
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@mork.no> wrote:
Lucas Tanure <tanure@linux.com> writes:
offp){ int nbytes; char * string = "hello World"; nbytes = copy_to_user(buf, string, 12); return nbytes; }
What is worg with my read operation?
static ssize_t misc_drv_read(struct file *filp, char __user * buf, size_t count, loff_t
copy_to_user returns the number of bytes which could *not* be copied. So it will return 0 on success, making your read return 0.
Bjørn