Week 17: Low-level Programming (Advanced)

Overview

Week 17 dives into low-level programming with Rust, exploring direct hardware interaction, operating system interfaces, and performance optimization through inline assembly. You’ll learn techniques for building systems software, direct memory manipulation, and how to leverage platform-specific features while maintaining Rust’s safety guarantees where possible.

Day 1-2: Memory-mapped I/O

Topics

• Memory-mapped I/O (MMIO) concepts:
  • Memory-mapped vs port-mapped I/O
  • Virtual memory and physical memory mapping
  • Page tables and memory protection
• Memory mapping in Rust:
  • Using mmap via libc
  • Safe abstractions with the memmap crate
  • Memory-mapped files
  • Shared memory between processes
• Direct hardware access:
  • Memory-mapped registers
  • Device drivers fundamentals
  • Volatile operations
  • Memory barriers and cache control
  • DMA (Direct Memory Access) concepts
• Platform-specific considerations:
  • Memory ordering
  • Alignment requirements
  • Atomic operations on MMIO regions

Resources

• Memmap Crate Documentation
• Memory-Mapped Files in Rust
• Volatile Memory Access
• Memory Barriers in Rust
• Linux Device Drivers in Rust

Use Cases

• Device drivers
• Embedded systems programming
• High-performance file I/O
• Inter-process communication
• Graphics programming
• Operating system development
• Direct hardware manipulation

Day 3-5: Operating System Interfaces

Topics

• System calls in Rust:
  • The nix crate for Unix-like systems
  • The winapi crate for Windows
  • Platform-specific abstractions
• File descriptors and I/O management:
  • Low-level file operations
  • Non-blocking I/O
  • Event-driven I/O (epoll, kqueue, IOCP)
• Building a custom async executor:
  • Event loops from scratch
  • Waker implementation
  • Task scheduling
  • Integrating with OS primitives
• Process and thread management:
  • Creating and managing processes
  • Signals and interrupts
  • Inter-process communication
  • Thread scheduling and priorities
• Security considerations:
  • Capabilities and privileges
  • Sandboxing
  • Seccomp filters (Linux)

Resources

• Nix Crate Documentation
• Building a Rust Runtime
• Writing an OS in Rust
• Async from Scratch
• IO_uring in Rust
• Syscalls in Rust

Use Cases

• Custom runtime development
• High-performance servers
• Operating system components
• File systems
• Process monitoring tools
• Network programming
• Security-critical applications

Day 6-7: Inline Assembly

Topics

• Rust’s inline assembly syntax:
  • Basic syntax and usage
  • The asm! macro
  • The global_asm! macro
  • Register constraints
  • Memory constraints
  • Clobbered registers
• Platform-specific assembly:
  • x86/x86_64 specifics
  • ARM/AArch64 specifics
  • RISC-V specifics
• Common use cases:
  • Performance optimization
  • CPU-specific instructions
  • Low-level algorithms
  • Atomics and synchronization primitives
• Safe abstractions over assembly:
  • Encapsulating assembly in safe APIs
  • Testing assembly code
  • Portability considerations
• SIMD intrinsics vs assembly

Resources

• Rust Inline Assembly
• Rust Assembly Syntax Guide
• Using Assembly in Rust
• x86 Assembly Reference
• ARM Assembly Reference
• SIMD in Rust

Use Cases

• Cryptographic algorithms
• Performance-critical code paths
• Direct hardware manipulation
• CPU feature detection
• Custom synchronization primitives
• Implementing missing instructions
• Low-level operations not exposed in Rust

Exercises

1. Create a memory-mapped file utility for fast file access
2. Implement a basic device driver using memory-mapped I/O
3. Build a simple event loop using platform-specific system calls
4. Create a custom executor for async tasks
5. Implement a performance-critical algorithm using inline assembly
6. Build a safe abstraction over a system call that isn’t exposed in the standard library

Advanced Challenges

1. Implement a shared memory IPC mechanism with synchronization
2. Create a cross-platform memory-mapped ring buffer
3. Build a custom scheduler for specialized workloads
4. Implement CPU-specific optimizations using inline assembly
5. Develop a safe wrapper for a complex system call interface

Next Steps

After completing Week 17, you’ll have a solid foundation in low-level programming with Rust. Week 18 will focus on embedded Rust, where you’ll apply these low-level skills to resource-constrained environments without the standard library.