NixOS for VisionFive 2

This flake hosts my take on running NixOS on the VisionFive 2.

Building & Running

A basic SD-card image can be created by building the sd package:

nix build github:Snektron/nixos-vf2#sd

The resulting image can be flashed to an SD card using dd, after decompressing:

zstd -d result/std-image/nixos-sd-image-*.img.zst -o sdcard.img
sudo dd if=sdcard.img of=/dev/your-disk bs=1M oflag=sync status=progress

Booting

The SD card image also contains a patched-up bootloader version. This means that the image is bootable on a new VisionFive 2 board without having to flash a newer bootloader version. To boot using this included bootloader the VisionFive 2 must be configured to boot from SDIO3.0, which can be done by setting the GPIO_0 switch to high (1), and the GPIO_1 switch to low (0). See also the VF2 quick start guide, 4.6. Boot Mode Settings.

Note: sometimes when pressing the reset switch, the only thing that shows up is

BOOT fail,Error is 0xffffffff

In this case, just keep pressing the reset switch until it works.

Flake features

• packages.${system}.kernel is a Linux kernel version that works on the VisionFive 2. Currently used is esmil/linux/jh7110.
• packages.${system}.splTool is StarFive's spl_tool, required for building firmware.
• packages.${system}.uboot is a patched u-boot that properly works with NixOS. This version properly fixes up the memory and ethernet device tree nodes, cleans up the initialization script, and enables booting from sd, mmc, and nvme.
• packages.${system}.opensbi is upstream OpenSBI configured to compile with the custom u-boot.
• packages.${system}.firmware creates u-boot-spl.bin and visionfive2_fw_payload.img from above u-boot and OpenSBI versions. These can also be flashed to the VisionFive 2's flash like the regular images, as described in the VF2 quick start guide, 4.3. Updating SPL and U-Boot.
• packages.${system}.sd is an alias that builds nixosConfiguration.sd.
• nixosConfigurations.sd is a basic bootable SD-card image. It starts sshd and sgetty on boot. Default credentials are root with password secret.
• nixosModules.sdImage is an implementation of sd-card.nix tweaked for booting the VisionFive 2. Besides the root filesystem, it contains a boot partition, OpenSBI and u-boot.
• devShells.${system}.default is a dev shell with picocom.