Helm v2a Armbian image builder

Creates an armbian image for Helm v2a (RK3399) with:

• Armbian Linux Build Framework
• Ubuntu 24.04 (noble) LTS base image
• Armbian Linux 6.12.55 Kernel
• Linux 6.12 based rk3399-helm-v2a.dtb.
• HelmSecure bootloader chain (idbloader.bin, uboot.img, and trust.bin)

Notes:

• The Helm v2a has rockchip secure boot enabled, so all components in the bootloader chain (idbloader.bin, uboot.img, and trust.bin) must be signed with a vendor private key. AFAICT this key is not publicly available, so we can't update any bootloader components, so we're we're stuck with an old and fragile version of U-Boot (2017.09-armbian). When building new images here we re-use those old components.
• The Linux 6.12 based rk3399-helm-v2a.dtb was created by decompiling and extracting configuration from the original Linux 4.4 based HelmSecure rk3399-helm-v2a.dtb.

Build Images

Prerequisites:

• Docker installed

./build.sh
...
LOADER=vendor/loader/helm-loader-build-38.bin
IMAGE=$(/bin/ls build/output/images/Armbian*.img | head -1)

Downloads Images

• LOADER: helm-loader-build-38.bin
• IMAGE: Armbian-unofficial_25.11.0-trunk_Helm-v2a_noble_current_6.12.55_minimal.img

Installation (via rkdeveloptool)

Notes:

• Helm v2 devices contain a Rockchip rk3399 SoC. The Rockchip rkdeveloptool running on a Linux host is required to flash the image. Instructions for installing rkdeveloptool can be found here: https://github.com/rockchip-linux/rkdeveloptool.

Procedure:

• Unplug the Helm power cable for at least 10 seconds.
• Hold the Helm power button and plug in the power cable. Continue to hold the power button for at least 6 seconds after plugging in the power cable, then release it. This process will put the Helm into maskrom mode.
• Connect to the Helm via a usb-c cable from your Linux host computer to usb0 on the Helm (the usb-c ports on the right of the ethernet port when looking at the Helm from the back).
• Confirm that your Linux host has detected the Helm is maskrom mode. Running the lsusb command on the Linux host should show a device named "Fuzhou Rockchip Electronics Company RK3399 in Mask ROM mode".
• Flash the image to your Helm using these commands:

rkdeveloptool db $LOADER
rkdeveloptool wl 0 $IMAGE
rkdeveloptool rd

Installing and running rkdeveloptool in a docker container

cat | sudo docker build -t rkflash - <<-EOF
FROM ubuntu:24.04

ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y \
    git build-essential pkg-config usbutils libusb-1.0-0-dev \
    autoconf automake libtool ca-certificates curl \
  && rm -rf /var/lib/apt/lists/*

# Build rkdeveloptool
RUN git clone https://github.com/rockchip-linux/rkdeveloptool /opt/rkdeveloptool && \
    cd /opt/rkdeveloptool && \
    autoreconf -i && \
    ./configure && \
    make -j"$(nproc)" && \
    cp rkdeveloptool /bin/rkdeveloptool

ENTRYPOINT ["/bin/bash"]
EOF
mkdir ~/rkflash-shared
cp $LOADER ~/rkflash-shared
cp $IMAGE ~/rkflash-shared
sudo docker run --rm -it \
    --privileged -v /dev/bus/usb:/dev/bus/usb -v /dev:/dev \
    -v "$HOME/rkflash-shared:/rkflash-shared" \
    rkflash
<... in the container ...>
cd /rkflash-shared
./rkdeveloptool db $LOADER
./rkdeveloptool wl 0 $IMAGE
./rkdeveloptool rd