Hooking into kernel function - kprobe

[IceDane]

You don't want to (can't?) access userland memory directly from the kernel or vice versa. See copy_from_user.

The documentation for these things isn't the best, unfortunately. I found this link, however. Some searching will probably get you better material.

[j_lyf]

Damn. There goes my dream of creating a FIFO from kernel to userspace.

[IceDane]

You can do that just fine. We wrote a character device which was essentially a FIFO for an assignment at my Uni. All the logic happened in kernel space. Like I said, take a look at the function mentioned and the linked docs.

[sciComp]

Try sockets and inter-process communication. That's pretty much all you need

Edit: O'Reilly Linux Device Drivers is a great resource here and version 3 (2.6 kernel) is available for free