CapazOS

CapazOS is a from-scratch AArch64 OS project that separates low-level kernel mechanisms from higher-level Core policy code.

Current active targets:

• aarch64-virt on QEMU virt
• aarch64-rpi3 bring-up sources exist, but virt is the primary validated runtime path

Current project state

Implemented and in active use:

• Platform layering split into architecture, board, and HAL surfaces
• HAL surfaces for uart, timer, irq, mmu, block, clock, and mailbox
• Virt bring-up with UART logging, MMU setup, GIC/timer wiring, and block I/O via virtio
• Loader target for virt with:
  • GPT partition discovery
  • FAT16 volume parsing
  • ELF kernel loading (KERNEL.ELF / KERNEL8.ELF)
  • boot_info handoff (including DTB pointer when available)
• Kernel + Core filesystem support:
  • Shared FAT parsing support
  • FAT16 and FAT32 read/write integration in Core-facing APIs
  • Format-agnostic FS calls used by Core services

Not implemented yet:

• Hardware trust chain enforcement (secure boot/attestation)
• Apple Silicon heterogeneous intent scheduling across CPU/GPU/NPU blocks
• Power contract and deterministic energy budget model
• User-space driver model and full capability-isolated user process model

Repository layout

• Kern/ kernel, arch code, HAL, loader
• Core/ Swift Core layer and shared filesystem logic
• Scripts/ build and packaging scripts
• Docs/ design and bring-up notes

Build

From /Users/cosas/CapazOS/Code/OS:

Build loader and kernel (default):

./Scripts/build.sh

Build only loader:

./Scripts/build.sh --loader

Build only kernel:

./Scripts/build.sh --kernel

Select platform explicitly (default is aarch64-virt):

./Scripts/build.sh --platform aarch64-virt

Common outputs in /Users/cosas/CapazOS/build/:

• loader.bin
• kernel.img
• kernel.elf

Run

Kernel image direct boot (virt):

qemu-system-aarch64 \
-machine virt,gic-version=2 \
-cpu cortex-a53 -smp 2 \
-m 128M \
-nographic \
-serial mon:stdio \
-kernel /Users/cosas/CapazOS/build/kernel.img

Loader boot (virt) with disk image:

qemu-system-aarch64 \
-machine virt,gic-version=2 \
-cpu cortex-a53 \
-m 128M \
-nographic \
-serial mon:stdio \
-kernel /Users/cosas/CapazOS/build/loader.bin \
-drive if=none,file=/Users/cosas/CapazOS/disk.img,format=raw,id=hd0 \
-device virtio-blk-device,drive=hd0

Loader disk requirements today:

• GPT disk
• At least one non-empty GPT partition
• FAT16 filesystem in selected partition
• KERNEL.ELF or KERNEL8.ELF at FAT root or subpath handled by loader lookup