tuhdo / os01

Operating Systems: From 0 to 1
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This book helps you gain the foundational knowledge required to write an
operating system from scratch. Hence the title, 0 to 1.
After completing this book, at the very least you will learn:
- How to write an operating system from scratch by reading hardware datasheets.
 In the real world, it works like that. You won't be able to consult Google for
 a quick answer.
- A big picture of how each layer of a computer is related to the other, from hardware to software.
- Write code independently. It's pointless to copy and paste code. Real learning
 happens when you solve problems on your own. Some examples are given to kick
 start, but most problems are yours to conquer. However, the solutions are
 available online for you to examine after giving it a good try.
- Linux as a development environment and how to use common tools for low-level
 programming.
- x86 assembly in-depth.
- How a program is structured so that an operating system can run.
- How to debug a program running directly on hardware with gdb and QEMU.
- Linking and loading on bare metal x86_64, with pure C. No standard library. No
 runtime overhead.
Download the book
# The pedagogy of the book
> You give a poor man a fish and you feed him for a day. You teach him to fish
> and you give him an occupation that will feed him for a lifetime.
This has been the guiding principle of the book when I was writing it. The book does
not try to teach you everything, but enough to enable you to learn by yourself.
The book itself, at this point, is quite "complete": once you master part 1 and
part 2 (which consist of 8 chapters), you can drop the book and learn by
yourself. At this point, smart readers should be able to continue on their own.
For example, they can continue their journeys
on OSDev wiki; in fact, after you study
everything in part 1 and part 2, you only meet
the minimum requirement by OSDev
Wiki (well, not quite, the book actually goes deeper for the suggested topics).
Or, if you consider developing an OS for fun is impractical, you can continue
with a Linux-specific book, such as this free
book Linux Insides, or other
popular Linux kernel books. The book tries hard to provide you a strong
foundation, and that's why part 1 and part 2 were released first.
The book teaches you core concepts, such as x86 Assembly, ELF, linking and
debugging on bare metal, etc., but more importantly, where such information
come from. For example, instead of just teaching x86 Assembly, it also teaches
how to use reference manuals from Intel. Learning to read the official
manuals is important because only the hardware manufacturers themselves
understand how their hardware work. If you only learn from the secondary
resources because it is easier, you will never gain a complete understanding of
the hardware you are programming for. Have you ever read a book on Assembly, and
wondered where all the information came from? How does the author know
everythin