This repository contains the kernel modules I've done to learn how Linux modules work. The project was part of a complementary project for the subject Estructura de Sistemas Operativos (Operating-System Structure).

The modules were tested using Ubuntu 16.04.4 LTS with Linux version 4.13.0-39-generic, and Fedora 27 with Linux version 4.15.13-300

• charEcho: The device has a buffer that can be written or read by any process (The buffer is emptied after a process reads it)
• charQuantumBreak: Creates a device that, when opened, changes the scheduling policy of the process to FIFO. (It is designed to give a process the full CPU to make the OS crash/slow down)

• procPid: Creates a proc file that when read, returns the pid of the process that opened it.
• cuentaSecuencial: Creates a proc file that when read, iterates through an array, printing every number between 0 and 99. It's a test to understand how sequence files work.
• procProcess: Creates a proc file that simulates a basic version of ps -ef. It prints the name, pid, and policy of every process.

• K-Input: Allows processes to get keyboard input from anywhere (not bound to the shell) using a Character device.

• Ubuntu

sudo apt-get install linux-headers-$(uname -r)

sudo apt-get install build-essential

• Fedora

sudo dnf install make automake gcc gcc-c++ kernel-devel

To build a module, you only have to run make in the module folder. To load the module, use sudo insmod module.ko (where module is the name of the module")

To unload the module use sudo rmmod module.ko

If when insmoded, the message ERROR: could not insert module module.ko: Invalid module format appears, do make clean, make and try to load it again.

Remember to open/run every file(device, proc file or C Test) with sudo permissions, or it won't work