LEARN OS DEVELOPMENT WITH RUST
Operating systems are the most complex software humans have ever created. They are the bridge between the physical world of silicon and electricity and the abstract world of applications.
Learn OS Development with Rust: From Zero to Kernel Master
Goal: Deeply understand how a computer actually works by stripping away all abstractions and building an operating system from scratch in Rust. You will learn to manage hardware directly, implement memory allocators, handle interrupts, design a scheduler, and eventually run a shell and user programs on your own kernel. By the end, you won’t just use an OS; you’ll understand why every byte in a computer moves the way it does.
Why OS Development Matters
Operating systems are the most complex software humans have ever created. They are the bridge between the physical world of silicon and electricity and the abstract world of applications.
- Historical Context: From the early days of manual switch-flipping to the birth of Unix at Bell Labs and the modern explosion of Linux and microkernels.
- The Ultimate Reality Check: In OS development, there is no “undefined behavior” hidden by a runtime. There is only the CPU, the memory, and your code.
- Unmatched Control: Understanding the kernel unlocks the ability to write high-performance drivers, secure systems, and efficient distributed platforms.
- First Principles: You stop asking “How does this library work?” and start asking “How does the hardware provide this capability?”
Core Concept Analysis
1. The Boot Sequence: From Power-On to Your Code
When you press the power button, the CPU doesn’t know about files or Rust. It starts at a hardcoded memory address and begins executing instructions.
+-----------+ +-----------+ +---------------+ +---------------+
| Reset | ----> | BIOS/ | ----> | Bootloader | ----> | Kernel |
| Vector | | UEFI | | (Stage 1 & 2) | | Entry |
+-----------+ +-----------+ +---------------+ +---------------+
^ | | |
CPU starts HW Init & Load Kernel Initialize
at 0xFFFFFFF0 Disk Scan into RAM Subsystems
2. Memory: The Giant Array
Memory isn’t a collection of variables; it’s a giant array of bytes. You must manage it using Paging, which maps “Virtual Addresses” (what your code sees) to “Physical Addresses” (where the bits live in RAM).
Virtual Address Space Page Tables Physical RAM
+-----------------+ +-------------+ +-----------------+
| Code (0x400) | -------> | Entry 1 ----|--------> | [Actual Bits] |
+-----------------+ +-------------+ +-----------------+
| Stack (0x700) | -------> | Entry 2 ----|--------> | [Actual Bits] |
+-----------------+ +-------------+ +-----------------+
| Heap (0x800) | -------> | Entry 3 ----|--------> | [Actual Bits] |
+-----------------+ +-------------+ +-----------------+
3. Interrupts: The Hardware’s “Hey!”
A CPU is a serial execution engine. Interrupts allow external hardware (keyboard, clock, disk) to pause the CPU, jump to a specific “Handler,” and then resume.
[ CPU Executing ] <----- ( IRQ 1: Keyboard Press )
|
v
[ Save Registers ]
|
[ Consult IDT ] --------> [ Keyboard Handler ]
| |
[ Restore Registers ] <----------+
|
[ Resume Execution ]
4. Processes and Scheduling: The Illusion of Simultaneity
CPUs can only do one thing at a time. The kernel creates the illusion of multitasking by “Context Switching” between processes hundreds of times per second.
Process A Kernel Scheduler Process B
+---------------------+ +-------------------+ +---------------------+
| PC: 0x123 | | 1. Timer fires | | PC: 0x456 |
| Registers: [Data] | ----> | 2. Save A State | | Registers: [Data] |
| Stack: [Values] | | 3. Pick Next (B) | ----> | Stack: [Values] |
+---------------------+ | 4. Load B State | +---------------------+
+-------------------+