Michael Smith
71debd0be2
Replace Buildroot toolchain references with the new docker-arm64 setup in CLAUDE.md, TOOLCHAIN.md, and the changelog. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
74 lines
2.9 KiB
Markdown
74 lines
2.9 KiB
Markdown
# Cross-Compilation Toolchain
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This document describes the target device and the arm64 Docker build container used to produce binaries for it.
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## Target Device
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### Hardware
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- **Device:** Anbernic RG35XX Plus
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- **SoC:** Allwinner H700 — quad-core ARM Cortex-A53 @ 1.5 GHz (AArch64 / ARMv8-A)
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- **GPU:** Mali G31 MP2
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- **RAM:** 1 GB LPDDR4
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- **Display:** 640×480 IPS
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### Software
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- **OS:** Ubuntu 22.04 LTS (Jammy Jellyfish) — [modified stock firmware](https://github.com/cbepx-me/Anbernic-H700-RG-xx-StockOS-Modification)
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- **Kernel:** Linux 4.9.170 aarch64 (proprietary, no source released by Anbernic)
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- **Architecture:** aarch64 / arm64 (confirmed via `dpkg --print-architecture`)
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- **glibc:** 2.35
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### Libraries on Device
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All required shared libraries are pre-installed. Most are at `/usr/lib/`, some at `/usr/lib/aarch64-linux-gnu/` (Debian multiarch path):
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| Library | Soname | Notes |
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|---------|--------|-------|
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| SDL2 | `libSDL2-2.0.so.0.12.0` | SDL 2.0.12 |
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| SDL2_image | `libSDL2_image-2.0.so.0.900.0` | SDL2_image 2.0.9, at multiarch path |
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| libavcodec | `libavcodec.so.58` | FFmpeg ~4.x |
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| libavformat | `libavformat.so.58` | FFmpeg ~4.x |
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| libavutil | `libavutil.so.56` | FFmpeg ~4.x |
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| libswresample | `libswresample.so.3` | FFmpeg ~4.x |
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### Implications for Cross-Compilation
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- The device userland is Debian/Ubuntu-based (has `dpkg`, `apt-get`, `systemd`)
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- Shared libraries are already present — no need to bundle or build them via Buildroot
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- A native aarch64 compile (e.g. inside an arm64 Docker container) produces working binaries
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- Must link against glibc ≤ 2.35 (use GCC ≤ 12 to avoid GLIBCXX version mismatches)
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## Build Container
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The `docker-arm64/` directory contains a Docker setup that runs an arm64 Ubuntu 22.04 container via QEMU user-mode emulation. This matches the target device exactly — same distro, same glibc 2.35, same library versions. The project's native `make` (using `pkg-config`) works as-is inside the container, no cross-compilation flags needed.
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### Prerequisites
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QEMU binfmt handlers must be registered on the host (one-time setup, persists across reboots):
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```sh
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docker run --privileged --rm tonistiigi/binfmt --install arm64
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```
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### Usage
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From the `docker-arm64/` directory:
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```sh
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make build # one-shot: build sdlamp2 inside the container
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make shell # interactive bash shell for development
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make clean # remove the Docker image
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```
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The container mounts the project root at `/workspace`. Output binary is `build/sdlamp2` (`ELF 64-bit ARM aarch64`).
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### Image Contents
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- **Base:** `ubuntu:22.04` (arm64)
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- **Build tools:** `build-essential`, `pkg-config`
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- **SDL2:** `libsdl2-dev`, `libsdl2-image-dev`
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- **FFmpeg:** `libavformat-dev`, `libavcodec-dev`, `libavutil-dev`, `libswresample-dev`
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The image is tagged `arm64-dev` and is generic enough to reuse for other projects targeting the same device.
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