2012/2/22 Ezequiel Garc?a [off-list ref]:

Hi Arokux,

On 2/22/12, Arokux B. [off-list ref] wrote:

quoted

Having my code as a module I can trigger its execution (load a module)
and disable it (unload a module). How can I achieve this if the code
is inside the kernel? One possibility I see is adding an entry in the
procfs.

I think you want to have the kernel execute some code of yours just for learning
purposes right?
So, your question could be put like this:
Where are the "doors" for me -userspace- to enter to the kernel?

In that case, I believe the "canonical" answer is: system calls.
If you have a copy of Love's book you could look there, or you could
just search through the
code and look how system calls are implemented and add own of your own.
Perhaps you could even modify one. You can search all syscalls definitions with:

grep "SYSCALL_DEFINE" `find . -name "*.c"`

Actually, that's the path I would take if I were to try this. You can
pick a simple syscall
like "getcwd", defined in fs/dcache.c and just add my test code there. That way
every time you call pwd in your shell, you get your code called (you
can check with
strace).

Hope this helps,
Ezequiel.

This is also a good summary of Kernel space / User space interfaces

http://people.ee.ethz.ch/~arkeller/linux/kernel_user_space_howto.html

Hope it helps,

-- 
Javier Mart?nez Canillas
(+34) 682 39 81 69
Barcelona, Spain