pi-os

A simple Raspberry PI / ARM toy operating system written in C and ARM assembly.

Goals

This project was intended for educational purposes only. You shouldn't use it in production ! (you won't go far with it anyway, stick with a GNU/Linux distribution instead !)

Here are the parts already implemented:

• Preemptive scheduler
• Memory Pagination management via ARM's MMU.
• Virtual Memory pager
• System calls

Here are the parts that will be implemented in the future:

• Memory protection between processes and kernel (Ring 0/Ring 1 separation)
• fork() syscall

Here are the parts that might be implemented in the future:

• Simple init system (pid 1)
• Basic FS
• Simple CLI

Usage

To make the development easier, you should use Vagrant:

vagrant up

Then you can ssh yourself into the vm that will be running the emulator.

vagrant ssh

Now it's compilation time !

cd /vagrant
make

And then, let's start qemu and gdb to control how the execution works...

cd /vagrant/debug
sh run-qemu.sh &
sh run-gdb.sh

At this point you can input c into gdb to go to the first breakpoint inside the kernel.

Getting to the next line will be n and entering inside a function call will be s.