Michael Cashwell wrote:
On Mar 24, 2008, at 10:43 AM, Carlo Bertoldi wrote:
Well, in the first module I used EXPORT_SYMBOL() to export my
function, and in the second one I have a function pointer to use it.
Not exactly. You would build the second module with a function prototype
for the exported function. Then you just call it normally. It's just
like using a function in a shared library. You don't need a function
pointer.
(If you want to use a function pointer for some other reason you can do
that too. But you still need the prototype for the actual exported
function and you'd assign that to your FP.)
Ok, I did that way because rummaging in kernel sources I found a file
(drivers/mtd/devices/docprobe.c, kernel version 2.6.18) with those
instructions.
So here what I'm doing right now in the second module:
extern void write_seq_to_store(void);
[..]
init function
{
void (*my_write) (void) = NULL;
if ( request_module("modulo_seq") < 0) {
printk(KERN_INFO "Unable to load module modulo_seq\n");
return -1;
}
my_write = symbol_request(write_seq_to_store);
write_seq_to_store it's implemented by modulo_seq.
You also will need to ensure that the module doing the exporting is
loaded successfully before you try to use the function and that it's not
used again after unloading it.
Yes. So now my problem is: where do I place the above code in the
kernel, such that it's executed early in the boot process?
Thanks,
Carlo
--
It's better to know something about everything, than everything about
something.
Blaise Pascal
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