NixOS on ARM/Banana Pi BPI-M5

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Note: To build an image for a BPI-M5 you will need to use flakes. If you don't know them or need to set them up for your system, follow the Flakes Wiki page.

Setting up the Flake for cross-compilation

Create a folder with a name of your choosing. In it create a flake.nix file with the following contents:

{
  description = "Banana Pi M5 NixOS Build Environment";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  outputs = { nixpkgs, ... }: let
    system = "x86_64-linux";
    pkgs = import nixpkgs { inherit system; };

    # Expose the correct AArch64 cross-compilation package set
    crossPkgs = import nixpkgs {
      inherit system;
      crossSystem = {
        config = "aarch64-unknown-linux-gnu";
      };
    };
  in {
    devShells.${system}.default = pkgs.mkShell {
      packages = [
        # For patching shebangs in the official build scripts
        pkgs.stdenv

        # Provides the 64-bit aarch64-unknown-linux-gnu-gcc
        crossPkgs.buildPackages.gcc

        # Retained for Amlogic's 32-bit SCP/BL30 binary generation
        pkgs.gcc-arm-embedded

        pkgs.ubootTools
        pkgs.dtc
        pkgs.flex
        pkgs.bison
        pkgs.swig

        pkgs.openssl
        pkgs.gnutls

        # Resolves the insecure Python 2 dependency
        pkgs.python3
      ];

      # Pre-set the build variables expected by Make
      shellHook = ''
        export CROSS_COMPILE="aarch64-unknown-linux-gnu-"
        export ARCH="arm"
      '';
    };
  };
}

Building Amlogic-compatible U-Boot

Building U-Boot

Note: Do not use the severely outdated BPI-M5-bsp or Amlogic-u-boot to build u-boot.

$ nix develop
$ git clone git://git.denx.de/u-boot.git
$ cd u-boot
$ make -j$(nproc) bananapi-m5_defconfig
$ make -j$(nproc)
$ cd ..

Creating Amlogic Package

Note: The following steps require an AMD64 platform.

$ git clone https://github.com/LibreELEC/amlogic-boot-fip
$ cd amlogic-boot-fip
$ mkdir -p output-bananapim5/
$ patchShebangs .
$ ./build-fip.sh bananapi-m5 ../u-boot/u-boot.bin output-bananapim5
$ hexdump -C -n 32 output-bananapim5/u-boot.bin | grep "40 41 4d 4c"
$ cd ..

Verify that the new u-boot.bin contains 40 41 4d 4c (@AML) at 0x10 onwards.

Board-specific installation notes

First follow the NixOS_on_ARM instructions to get the SD card image and decompress it.

Once the image has been decompressed, the Amlogic U-Boot package needs to be copied to byte 512+ inside the image (replace the image with the name downloaded and decompressed image):

$ sudo dd if=amlogic-boot-fip/output-bananapim5/u-boot.bin of=nixos-sd-image-22.11.2620.de5448dab58-aarch64-linux.img conv=fsync,notrunc bs=512 seek=1

Then, copy the image onto the eMMC or sdcard using the the installation steps.

In order to get a serial console output, it is required to replace ttyAMA0 with ttyAML0 in the /boot/extlinux/extlinux.conf file inside the image. The easiest way is to just mount the respective folder after the image has been flashed on the SD-card

$ sudo mount /dev/sdX /mnt/
$ sudo sed -i 's/ttyAMA0/ttyAML0/g' /mnt/boot/extlinux/extlinux.conf

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