Michael Smith
0f653d4395
sdlamp2 now catches SIGTERM and SIGINT via a sig_atomic_t flag checked in the main loop, ensuring position and volume are saved before exit. Previously, a kill signal would terminate instantly without saving. New tools/rg35xx-wrapper.sh replaces sdlamp2 as the dmenu_ln CMD on the RG35XX Plus. Skeleton includes placeholders for WiFi hotspot and power button monitoring (TBD after on-device investigation). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
129 lines
6.2 KiB
Markdown
129 lines
6.2 KiB
Markdown
# Anbernic RG35XX Plus
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Device-specific reference for the target hardware. For build instructions see [`TOOLCHAIN.md`](TOOLCHAIN.md).
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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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- **Userland:** Debian/Ubuntu-based (`dpkg`, `apt-get`, `systemd`)
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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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Shared libraries are already present — no need to bundle or build them. A native aarch64 compile (e.g. inside the arm64 Docker container) produces working binaries. Must link against glibc ≤ 2.35.
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## Partition Layout
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| Device | Mount point | Filesystem | Contents |
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|--------|-------------|------------|----------|
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| `/dev/mmcblk0p5` | `/` | ext4 | Root filesystem |
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| `/dev/mmcblk0p6` | `/mnt/vendor` | ext4 | Firmware, apps, scripts |
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| `/dev/mmcblk0p7` | `/mnt/data` | ext4 | User data |
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| `/dev/mmcblk0p8` | `/mnt/mmc` | vfat | ROMs |
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| SD card slot | `/mnt/sdcard` | (varies) | External storage |
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## Boot Chain
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The device uses systemd but boots its UI through a SysV init script that systemd auto-wraps via `systemd-sysv-generator`. The chain is intentionally layered: `launcher.sh` runs before partitions are mounted (hardware setup), `loadapp.sh` runs after mounts (filesystem/network setup + app restart loop), and `dmenu_ln` is the app dispatcher.
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```
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systemd (graphical.target)
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└─ launcher.service (SysV → auto-generated by systemd-sysv-generator)
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└─ /etc/init.d/launcher.sh start
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├── mounts /mnt/vendor
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├── starts brightCtrl.bin (backlight daemon) &
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├── starts cexpert &
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└── starts loadapp.sh &
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├── resizes root partition (first boot only)
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├── mounts /mnt/data, /mnt/mmc
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├── charging mode: if boot_mode==1 → charger UI → poweroff
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├── normal mode: starts NetworkManager, bluetooth, wifi
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├── syncs RTC, loads kernel modules, mounts SD card
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├── runs /mnt/mod/ctrl/autostart (if exists)
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└── RESTART LOOP: runs /mnt/vendor/ctrl/dmenu_ln repeatedly
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└─ /mnt/vendor/ctrl/dmenu_ln
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├── selects binary (default: dmenu.bin)
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├── config overrides: muos.ini → muos.bin, vpRun.ini → ...
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├── runs binary via app_scheduling()
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└── on exit: executes /tmp/.next (app dispatch for menu)
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```
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### Why the indirection?
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- **`launcher.sh`** — Pre-mount hardware setup: mounts `/mnt/vendor`, starts backlight and system daemons. Runs as a SysV init script so it integrates with systemd's boot ordering.
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- **`loadapp.sh`** — Post-mount filesystem/network setup: mounts data partitions, handles charging mode, starts networking, then enters the restart loop. Runs in the background (`&`) so `launcher.sh` can return.
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- **`dmenu_ln`** — App dispatcher: selects which binary to run based on config files, wraps execution in `app_scheduling()` (which sleeps 30s on crash before retrying), and supports `/tmp/.next` for menu-driven app switching.
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### `app_scheduling` behavior
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The `app_scheduling` function in `dmenu_ln` runs the selected binary. If it exits with a non-zero status, it sleeps 30 seconds before returning, which prevents crash loops from consuming all CPU. The outer `while true` loop in `loadapp.sh` then re-invokes `dmenu_ln`, restarting the application.
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## Deploying sdlamp2
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### Overview
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The `dmenu_ln` script already supports switching the startup binary via config files (e.g. `muos.ini` → `muos.bin`). We follow the same pattern to launch sdlamp2 instead of the default menu.
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### Setup
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1. **Copy the binary and wrapper** to the device:
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```sh
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scp build/sdlamp2 root@<device>:/mnt/vendor/bin/sdlamp2
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scp tools/rg35xx-wrapper.sh root@<device>:/mnt/vendor/bin/rg35xx-wrapper.sh
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```
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2. **Add the config check** to `/mnt/vendor/ctrl/dmenu_ln`. In the section where `CMD` overrides are checked (after the existing `muos.ini` / `vpRun.ini` checks, before the `app_scheduling` call), add:
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```bash
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if [ -f "/mnt/vendor/sdlamp2.ini" ];then
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CMD="/mnt/vendor/bin/rg35xx-wrapper.sh"
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fi
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```
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The wrapper script handles device-specific concerns (WiFi hotspot, power button monitoring) and launches sdlamp2 as its main foreground process. See `tools/rg35xx-wrapper.sh` for details.
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3. **Enable sdlamp2 on boot:**
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```sh
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touch /mnt/vendor/sdlamp2.ini
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```
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4. **Disable** (revert to normal menu):
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```sh
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rm /mnt/vendor/sdlamp2.ini
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```
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### What's preserved
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Everything else in the boot chain continues to work:
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- **Charging mode** — handled in `loadapp.sh` before the restart loop
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- **LED/backlight control** — `brightCtrl.bin` started by `launcher.sh`
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- **Clean shutdown** — sdlamp2 handles SIGTERM/SIGINT, saving position and volume before exit. The wrapper script can trigger `poweroff` after sdlamp2 exits
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- **Restart on exit** — if sdlamp2 exits cleanly (status 0), the restart loop in `loadapp.sh` re-launches it immediately
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- **Crash recovery** — if sdlamp2 crashes (non-zero exit), `app_scheduling` sleeps 30s then the loop retries
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- **Easy revert** — removing `sdlamp2.ini` restores the stock menu on next boot
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