# Osdev Notes

[![Discord Chat](https://img.shields.io/discord/578193015433330698.svg?style=flat)](https://discordapp.com/channels/578193015433330698/578193713340219392)
<span class="badge-buymeacoffee">
<a href="https://buymeacoffee.com/dreamos82" title="Donate to this project using Buy Me A Coffee"><img src="https://img.shields.io/badge/buy%20me%20a%20coffee-donate-yellow.svg" alt="Buy Me A Coffee donate button" /></a>
</span>
![](https://tokei.rs/b1/github/dreamos82/osdev-notes)

**IMPORTANT**: _The developmen has moved to codeberg: [https://codeberg.org/dreamportdev/Osdev-Notes](https://codeberg.org/dreamportdev/Osdev-Notes), github repository will be left as a mirror, although we will still keep an eye there, we appreciate if future PR will be done on Codeberg._

A book, originated as a collection of notes, intended to guide a reader through the steps of building an operating system kernel from scratch. Written while writing (and re-writing) our own kernels, each chapter covers a step of the process from selecting a bootloader to running a loaded ELF in userspace.

We hope you enjoy, and find something interesting here!

The content of this repository is also available as a _**printed book**_, it can be purchased via Lulu:
* **Paperback**: [Click here](https://www.lulu.com/shop/dean-tuckey-and-ivan-gualandri/osdev-notes/paperback/product-mpzp5v.html?q=osdev+notes&page=1&pageSize=4)
* **Hardcover**: [Click Here](https://www.lulu.com/shop/dean-tuckey-and-ivan-gualandri/osdev-notes/hardcover/product-je5drpr.html?page=1&pageSize=4)

The [latest-master](https://codeberg.org/dreamportdev/Osdev-Notes/releases/tag/latest-master) release contains the PDF built from master.

You can reach us on 
* Discord: [https://discord.gg/NGasazGkqr](https://discord.gg/NGasazGkqr)
* FLuxer: [https://fluxer.gg/8L9eRwcy](https://fluxer.gg/8L9eRwcy)

## Current Chapters:

* [Part 0: Introduction](00_Introduction/01_README.md)
    * [Assumed Knowledge](00_Introduction/02_AssumedKnowledge.md)
    * [About The Authors](00_Introduction/03_AboutTheAuthors.md)
* [Part 1: Building & Boot Protocols](01_Build_Process/README.md)
    * [Building a Kernel](01_Build_Process/01_Overview.md)
    * [Bootloaders and Boot Protocols](01_Build_Process/02_Boot_Protocols.md)
    * [Makefiles](01_Build_Process/03_Gnu_Makefiles.md)
    * [Linker Scripts](01_Build_Process/04_Linker_Scripts.md)
    * [Generating a Bootable Iso](01_Build_Process/05_Generating_Iso.md)
* [Part 2: Architecture and Basic Drivers](02_Architecture/README.md)
    * [Overview](02_Architecture/01_Overview.md)
    * [Hello World](02_Architecture/02_Hello_World.md)
    * [A Higher Half Kernel](02_Architecture/03_HigherHalf.md)
    * [Global Descriptor Table](02_Architecture/04_GDT.md)
    * [Interrupts](02_Architecture/05_InterruptHandling.md)
    * [ACPI Tables](02_Architecture/06_ACPITables.md)
    * [APIC](02_Architecture/07_APIC.md)
    * [Timers](02_Architecture/08_Timers.md)
    * [PS2 Keyboard Overview](02_Architecture/09_Add_Keyboard_Support.md)
    * [PS2 Keyboard Interrupt Handling](02_Architecture/10_Keyboard_Interrupt_Handling.md)
    * [PS2 Keyboard Driver implementation](02_Architecture/11_Keyboard_Driver_Implemenation.md)
* [Part 3: Video Output](03_Video_Output/README.md)
    * [The Framebuffer](03_Video_Output/01_Framebuffer.md)
    * [Drawing Text on Framebuffer](03_Video_Output/02_DrawingTextOnFB.md)
* [Part 4: Memory Management](04_Memory_Management/README.md)
    * [Overview](04_Memory_Management/01_Overview.md)
    * [Physical Memory](04_Memory_Management/02_Physical_Memory.md)
    * [Paging](04_Memory_Management/03_Paging.md)
    * [Virtual Memory Manager](04_Memory_Management/04_Virtual_Memory_Manager.md)
    * [Heap Allocation](04_Memory_Management/05_Heap_Allocation.md)
* [Part 5: Scheduling](05_Scheduling/README.md)
    * [Overview](05_Scheduling/01_Overview.md)
    * [The Scheduler](05_Scheduling/02_Scheduler.md)
    * [Processes and Threads](05_Scheduling/03_Processes_And_Threads.md)
    * [Locks](05_Scheduling/04_Locks.md)
* [Part 6: Getting to Userspace](06_Userspace/README.md)
    * [Overview](06_Userspace/01_Overview.md)
    * [Switching Modes](06_Userspace/02_Switching_Modes.md)
    * [Updated Interrupt Handling](06_Userspace/03_Handling_Interrupts.md)
    * [System Calls](06_Userspace/04_System_Calls.md)
    * [Example Syscall ABI](06_Userspace/05_Example_ABI.md)
    * [Resource Management](06_Resource_Management.md)
* [Part 7: Inter-Process Communication](07_IPC/README.md)
    * [Overview](07_IPC/01_Overview.md)
    * [Shared Memory](07_IPC/02_Shared_Memory.md)
    * [Message Passing](07_IPC/03_Message_Passing.md)
* [Part 8: File System](08_VirtualFileSystem/README.md)
    * [Overview](08_VirtualFileSystem/01_Overview.md)
    * [The Virtual File System](08_VirtualFileSystem/02_VirtualFileSystem.md)
    * [The Tar File System](08_VirtualFileSystem/03_TarFileSystem.md)
* [Part 9: Loading & Executing ELFs](09_Loading_Elf/README.md)
    * [Theory](09_Loading_Elf/01_Elf_Theory.md)
    * [Loading and Running](09_Loading_Elf/03_Loading_And_Running.md)
* [Part 10: Going Beyond](10_Going_Beyond/README.md)
* [Extras: Appendices](99_Appendices/README.md)
    * [General Troubleshooting](99_Appendices/A_Troubleshooting.md)
    * [Tips and Tricks](99_Appendices/B_Tips_And_Tricks.md)
    * [C Language](99_Appendices/C_Language_Info.md)
    * [Working With NASM](99_Appendices/D_Nasm.md)
    * [All About Cross Compilers](99_Appendices/E_Cross_Compilers.md)
    * [Debugging](99_Appendices/F_Debugging.md)
    * [Memory Protection](99_Appendices/G_Memory_Protection.md)
    * [Useful Resources](99_Appendices/H_Useful_Resources.md)
    * [Acknowledgments](99_Appendices/I_Acknowledgments.md)

## Our Projects

* [DreamOs64](https://codeberg.org/dreamos82/Dreamos64): 64-bit OS written from scratch by [Ivan G](https://codeberg.org/dreamos82).
* [Northport](https://github.com/DeanoBurrito/northport): Another 64-bit OS with SMP, and riscv support! by [Dean T](https://github.com/DeanoBurrito/).
* [DreamOs](https://github.com/dreamos82/Dreamos): 32-bit OS written from scratch. This project is discontinued, but it still worth mentioning. Also by [Ivan G](https://codeberg.org/dreamos82).

## Authors

* [Ivan G](https://codeberg.org/dreamos82) (dreamos82) - Author and creator of these notes.
* [Dean T](https://codeberg.org/r4) (DeanoBurrito) - Author.

## License

The contents (code, text and other assets) of this repository are licensed under the Creative Commons Attribution-NonCommercial 4.0 Public License, see the [LICENSE](LICENSE.md) file for the full text.

While not legal advice, this license can be summed up as:
- You are free to share (copy and redistribute) this material in any medium or format.
- Adapt (remix, transform and build upon) the material.

Under the following restrictions:
- You must give appropriate credit, provide a link to the license, and indicate if changes were made.
- You cannot use the material for commercial uses.

Note that no warranties of any kind are provided.

<a rel="license" href="http://creativecommons.org/licenses/by-nc/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc/4.0/88x31.png" /></a>