GitHub - Yumi-Lab/SmartPi-BSP-kernel-linux: Minimal Board Support Package for SmartPi One (Allwinner H3)

Minimal Board Support Package for SmartPi One (Allwinner H3) — Buildroot-based, boots in 5 seconds.

The lightest possible Linux image for the SmartPi One. No desktop, no package manager, no bloat. Just a kernel, a shell, WiFi and SSH. The perfect starting point to build your own embedded project.

Hardware

Spec	Detail
Board	SmartPi One (Yumi Lab)
SoC	Allwinner H3 — Cortex-A7 quad-core @ 1.2 GHz
RAM	1 GB DDR3 (576 MHz, custom ZQ/ODT tuning)
GPU	Mali-400 MP2 (GLES 2.0)
WiFi	RTL8188EU (on-board)
Storage	MicroSD
Video	HDMI 1080p + Composite

What's inside

Component	Detail	Size
Kernel	Linux 6.6.56 LTS (mainline sunxi)	~5 MB
U-Boot	2023.01, nanopi_m1 + custom DRAM tuning	~400 KB
libc	musl (lightweight, no glibc bloat)	~600 KB
Init	BusyBox init (no systemd)	—
Shell	BusyBox ash + nano editor	~1 MB
WiFi	wpa_supplicant + RTL8188EU firmware	~1.2 MB
SSH	Dropbear (lightweight SSH server + client)	~200 KB
Network	udhcpc (DHCP) + iproute2 + iptables	~500 KB
Monitoring	htop	~100 KB
Total rootfs		~15 MB

What's NOT inside (by design)

No systemd — BusyBox init, boots in seconds
No apt/dpkg — no package manager overhead
No glibc — musl libc, 3x lighter
No NetworkManager — wpa_supplicant direct
No man pages, locales, docs — bare minimum
No desktop environment — console only

Quick start

Build

Requires a Linux x86_64 machine (native, VM, or WSL2). See docs/BUILD-VM-SETUP.md for Windows users.

git clone https://github.com/Yumi-Lab/SmartPi-BSP-kernel-linux.git
cd SmartPi-BSP-kernel-linux
make build

First build takes ~1-2 hours (downloads + compiles the entire toolchain, kernel, and packages). Subsequent rebuilds: 5-15 minutes (Buildroot cache).

Output: buildroot/output/images/sdcard.img

Flash

# Find your SD card device (e.g. /dev/sdb)
lsblk

# Flash (replace /dev/sdX with your device)
sudo dd if=buildroot/output/images/sdcard.img of=/dev/sdX bs=1M status=progress
sync

Warning: Do NOT use Balena Etcher with Allwinner H3 images — use dd only.

First boot

Insert SD card into SmartPi One, power on
Console available on HDMI or UART (ttyS0, 115200 baud)
Login: root / yumi

Configure WiFi

# Generate WiFi config
wpa_passphrase "YourSSID" "YourPassword" > /etc/wpa_supplicant.conf

# Start WiFi
/etc/init.d/S45wifi start

# Check IP
ip addr show wlan0

SSH access

From another machine on the same network:

Customize

make menuconfig         # Add/remove Buildroot packages
make linux-menuconfig   # Kernel configuration
make build              # Rebuild image

Add packages examples

Open make menuconfig and enable:

Python → BR2_PACKAGE_PYTHON3
Node.js → BR2_PACKAGE_NODEJS
Docker → not recommended on 1GB RAM H3
Klipper → custom package needed
GPIO tools → BR2_PACKAGE_LIBGPIOD + BR2_PACKAGE_LIBGPIOD_TOOLS

Project structure

SmartPi-BSP-kernel-linux/
├── configs/
│   └── smartpi_one_defconfig       # Buildroot defconfig (all build options)
├── board/smartpi-one/
│   ├── uboot.config.fragment       # U-Boot DRAM tuning (576MHz, ZQ, ODT)
│   ├── genimage.cfg                # SD card partition layout (boot + rootfs)
│   ├── post-build.sh               # Runs after rootfs build
│   ├── post-image.sh               # Generates final SD card image
│   ├── boot/
│   │   └── extlinux.conf           # Kernel boot parameters
│   └── rootfs-overlay/             # Files injected into the rootfs
│       └── etc/
│           ├── init.d/
│           │   ├── S40network      # Ethernet auto-start
│           │   └── S45wifi         # WiFi auto-start
│           └── issue               # Login banner
├── docs/
│   └── BUILD-VM-SETUP.md           # Build guide for Windows + Ubuntu VM
├── Makefile                        # Top-level build wrapper
└── .github/workflows/
    └── build.yml                   # CI build on self-hosted runner

How it works

Power On
  → U-Boot (nanopi_m1 + SmartPi DRAM tuning)
    → Linux kernel 6.6 (sun8i-h3-nanopi-m1.dtb)
      → BusyBox init
        → S40network (Ethernet DHCP)
        → S45wifi (WiFi if configured)
        → Dropbear SSH
        → Login prompt (tty0/ttyS0)

Boot time: ~5 seconds to login prompt
RAM usage: ~30-50 MB idle

Use cases

This BSP is a foundation layer. Build on top of it:

Project	What to add
Retrogaming	RetroArch, EmulationStation, libretro cores
3D Printer (Klipper)	Klipper, Moonraker, Fluidd/Mainsail
IoT Gateway	MQTT, Node-RED, GPIO tools
Home automation	Home Assistant core, Zigbee/Z-Wave
Network appliance	Pi-hole, WireGuard, hostapd
Education	Python, Jupyter, GPIO tutorials

Related projects

Project	Description
RetroMi	Full retrogaming image (RetroPie + EmulationStation on Armbian)
Batocera-SmartPiOne	Batocera retrogaming distribution for SmartPi One
SmartPi-armbian	Armbian-based server image for SmartPi One

Build requirements

Resource	Minimum	Recommended
OS	Linux x86_64 (Ubuntu 22.04+)	Ubuntu 24.04
Disk	15 GB	30 GB
RAM	4 GB	8 GB
CPU	2 cores	4+ cores
Time	2 hours	1 hour (8 cores)

License

MIT — Free to use, modify, and redistribute.