Linux Kernel Module Cheat

File operations are the main method of userland driver communication.

struct file_operations determines what the kernel will do on filesystem system calls of Pseudo filesystems.

This example illustrates the most basic system calls: open, read, write, close and lseek:

Outcome: the test passes:

Sources:

Then give this a try:

We have put printks on each fop, so this allows you to see which system calls are being made for each command.

No, there no official documentation: https://stackoverflow.com/questions/15213932/what-are-the-struct-file-operations-arguments