JP Beaudry wrote:
Hi,
I want to add a virtual file under /proc for my module (kernel 2.4.21).
The "registration" seems to work because /proc/foo shows up once my
module is loaded. Here's the call:
create_proc_read_entry("foo", 0, NULL, foo_read, NULL);
My problem is that nothing shows up when I read foo with 'cat' or
'less'. Here's foo():
int foo_read(char *buf, char **start, off_t offset, int count, int *eof,
void *data)
{
printk("Got into foo_read\n");
int len = sprintf(buf, "hello");
*eof = 1;
return len;
}
As you can see, I've used printk() in the hope of asserting that foo()
is called. Unfortunately, I can't see anything in /var/log/messages. I
don't even know if I should expect printk() to work in this context. I
tried both with and without with the same result.
What am I missing?
Thanks,
JP
Hi,
replace
create_proc_read_entry("foo", 0, NULL, foo_read, NULL);
by
create_proc_read_entry("foo", 0644, NULL, foo_read, NULL);
to have correct permissions on the file.
I don't think this will resolve the problem. Maybe you could test the
value return by create_proc_read_entry() to check if the file has
effectively been created.
Anyway, here's a guide for procfs :
http://kernelnewbies.org/documents/kdoc/procfs-guide/lkprocfsguide.html
If your error persist, send the complete code.
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