# Personal NixOS RISC-V 64 flake

Goals:

* I want to flash NixOS on to the M.2 NVMe SSD of a VisionFive2
* I want a flake with a neat cross story / UX

# Nix?

* https://nixos.org/
* https://determinate.systems/posts/determinate-nix-installer

# How?

The VisionFive2 shipped with a stinky firmware, which does not support booting from the SSD.
This capability was later added in [starfive uboot v3.0.4](https://github.com/starfive-tech/u-boot/commit/2139bf20ea67250c9dc426735fb9daf14e21bb9f).
As such we have to flash an SD card, use it to flash new firmware to the VisionFive2 SPI flash, then finally boot from the NVMe, all the while [fiddling with DIP switches](dip-pics.md).

## Building an image

Pick a host, then pick your poison:

| Hostname       | Description         |
| -------------- | ------------------- |
| `demo-r12a`    | Board rev 1.2A      |
| `demo-r12a-8g` | Board rev 1.2A, 8GB |
| `demo-r13b`    | Board rev 1.3B      |
| `demo-r13b-8g` | Board rev 1.3B, 8GB |
| `asgaut`       | Asgaut              |
| `gunder`       | Gunder              |

```shell
nix build .#asgaut-qemu # emulation go brr
nix build .#asgaut-nvme-image
nix build .#asgaut-sd-image
nix build .#asgaut-sd-installer
```

## Building without cross compilation

Either use a `riscv64-linux` host, or run the following command with `riscv64-linux` [binfmt emulation](https://search.nixos.org/options?query=boot.binfmt.emulatedSystems) configured:

```shell
nix build .#packages.riscv64-linux.demo-nvme-image
```

## Flashing an image

```shell
nix build .#something
lsblk # locate your SD card
umount /run/media/pbsds/9C33-6BBD # example mounts
sudo dd if=result/sd-image/*.img of=/dev/sdX bs=4M conf=fsync status=progress
sync
```

## Booting

Here are some sweet [dip pics](https://doc-en.rvspace.org/VisionFive2/Boot_UG/VisionFive2_SDK_QSG/boot_mode_settings.html).

After flashing the firmware you can boot using quad SPI. Use SDIO3.0 to boot using the u-boot SPL and FIT firmware on the sd card.

## Updating SPI firmware

```shell
sudo update-firmware
```