HeliOS OS Image Build Guide

This repository contains everything needed to produce a bootable HeliOS image for Raspberry Pi Compute Modules. Image builds are orchestrated by the Gaia builder CLI (gaia) using the in-repo buildchain under gaia/.

Daedalus Type System Notes (Performance-Critical)

HeliOS uses Daedalus to run CV graphs. If you work on backend/src/libs/lib-cv (nodes, node-groups, types), read AGENTS.md first.

Two key points:

1. TypeExpr is graph/UI typing, not the runtime carrier.

   • It defines port schemas for the editor/JSON and should be stable at graph boundaries.

2. GPU/CPU conversions only happen in specific runtime paths.

   • A node input typed as Payload<T> can trigger upload/download (based on ComputeAffinity and GPU availability).
   • A node input typed as plain T (e.g. DynamicImage) will still work with GPU-resident upstream values: Daedalus will download as needed and then apply registered CPU conversions.
   • ErasedPayload memoization means GPU->CPU downloads are cached across fanout of the same payload; don’t add conversion-only nodes to “dedupe” downloads.

For the concrete rules and code-level references, see AGENTS.md.

Requirements

• Rust toolchain (edition 2024), Cargo and cross installed.
• Standard native build packages: pkg-config, libcamera-devel, turbojpeg-devel, nasm, cmake, ffmpeg-devel.
• Docker or Podman for the cross container build stage.
• Enough disk space for Gaia Buildroot caches (gaia/build) and final images (gaia/output).

Build Instructions

See BUILD.md for Gaia install/build steps.

License

GPL-2.0-only. See COPYING.