Project 3: Bare-Metal Framebuffer Graphics (Raspberry Pi 4/5)

A bare-metal program in AArch64 assembly that initializes the GPU mailbox, requests a framebuffer, and draws graphics directly to the screen—no Linux, no libraries.

Quick Reference

Attribute Value
Primary Language See main guide
Alternative Languages N/A
Difficulty Level 4: Expert
Time Estimate 1-2 weeks
Knowledge Area Graphics / Embedded Systems
Tooling Raspberry Pi 4 / VideoCore
Prerequisites Comfort with 32-bit ARM concepts, understanding of pointers and memory

What You Will Build

A bare-metal program in AArch64 assembly that initializes the GPU mailbox, requests a framebuffer, and draws graphics directly to the screen—no Linux, no libraries.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Writing AArch64 boot code that sets up the stack and clears BSS
  • Understanding the VideoCore mailbox interface for framebuffer allocation
  • Implementing memory barriers (dmb, dsb) for peripheral access
  • Drawing pixels by calculating memory offsets from (x, y) coordinates
  • Optimizing drawing loops with AArch64’s larger register file

Key Concepts

  • AArch64 Architecture: “Modern Arm Assembly Language Programming” Ch. 1, 17 - Daniel Kusswurm
  • 64-bit Calling Convention: “The Art of ARM Assembly, Volume 1” Ch. 16 - Randall Hyde
  • Memory Barriers: ARM Architecture Reference Manual (ARM DDI 0487) - Section B2.3
  • Raspberry Pi Mailbox: OSDev Wiki - Raspberry Pi Bare Bones

Real-World Outcome

Pixel grid (x increases right, y increases down):
(0,0) (1,0) (2,0) (3,0)
(0,1) (1,1) (2,1) (3,1)
(0,2) (1,2) (2,2) (3,2)

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: ARM_ASSEMBLY_LEARNING_PROJECTS.md
  • “Modern Arm Assembly Language Programming” by Daniel Kusswurm