NixOS on ARM/Raspberry Pi

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Raspberry Pi Family
Raspberry Pi
Architecture	ARMv6
Raspberry Pi 2
Architecture	ARMv7
Raspberry Pi 3
Architecture	AArch64 + ARMv7

Status

Only the Raspberry Pi 3 is supported upstream, with the aarch64 effort.

Other Raspberry Pis are part of @dezgeg's porting efforts to ARMv6 and ARMv7.

Board-specific installation notes

First follow the generic installation steps to get the installer image and install using the installation and configuration steps.

Raspberry Pi (1)

The ARMv6 image boots out-of-the-box.

Raspberry Pi 2

The ARMv7 image should boot out-of-the-box, though the author hasn't personally tested this.

Raspberry Pi 3

Both the AArch64 and ARMv7 images boot out-of-the-box. Using the 64-bit AArch64 image is highly recommended, as the availability of binaries is much better and allows the use of the 64-bit instruction set.

Use the following GPIO Pins with an USB-TTL connector:

GND         - 3rd in top row, black cable
GPIO 14 TXD - 4th in top row, white cable
GPIO 15 RXD - 5th in top row, green cable

Use nix-shell -p screen --run "screen /dev/ttyUSB0 115200" to connect to the console.

Note: Right now (2017-10-08) wifi is not working out of the box on the Raspberrypi 3, you will need to use ethernet. Add the following to your configuration.nix. This requires linux kernel > 4.13.0

{
  ...
  hardware.enableRedistributableFirmware = true;
  hardware.firmware = [
    (pkgs.stdenv.mkDerivation {
     name = "broadcom-rpi3-extra";
     src = pkgs.fetchurl {
     url = "https://raw.githubusercontent.com/RPi-Distro/firmware-nonfree/54bab3d/brcm80211/brcm/brcmfmac43430-sdio.txt";
     sha256 = "19bmdd7w0xzybfassn7x4rb30l70vynnw3c80nlapna2k57xwbw7";
     };
     phases = [ "installPhase" ];
     installPhase = ''
     mkdir -p $out/lib/firmware/brcm
     cp $src $out/lib/firmware/brcm/brcmfmac43430-sdio.txt
     '';
     })
  ];
  networking.wireless.enable = true;
}

Serial console

Your configuration.nix will need to add console=ttyS0,115200n8 to the boot.kernelParams configuration to use the serial console.

/etc/nixos/configuration.nix

{ config, pkgs, lib, ... }:
{
  boot.kernelParams = [
    "console=ttyS0,115200n8"
  ];
}

Camera

For the camera to work, you will need to add the following code to your configuration.nix:

Note: Two pull requests (#38490 and #38342) are required to make this configuration.nix and the camera working.

/etc/nixos/configuration.nix

{ config, pkgs, lib, ... }:
{
  boot.loader.raspberryPi.enable = true;
  # Set the version depending on your raspberry pi. 
  boot.loader.raspberryPi.version = 3;
  # We need uboot
  boot.loader.raspberryPi.uboot.enable = true;
  # These two parameters are the important ones to get the
  # camera working. These will set `start_x=1` and 
  # `gpu_mem=256` in /boot/configuration.txt
  boot.loader.raspberryPi.uboot.startx = true;
  boot.loader.raspberryPi.uboot.gpu_mem = 256;
}

Note: A reboot is required to load the new firmware configuration.

To make the camera available as v4l device under /dev/video0 the bcm2835-v4l2 kernel module need to be loaded. This can be done by adding the following code to your configuration.nix:

/etc/nixos/configuration.nix

{ config, pkgs, lib, ... }:
{
  boot.kernelModules = [ "bcm2835-v4l2" ];
}

Binary Cache

Depending on the architecture used, binary caches availability varies. Binary caches instructions are on the main NixOS on ARM page. The following table desribes the architectures supported by each board.

Raspberry Pi 1	armv6
Raspberry Pi 2	armv7
Raspberry Pi 3	armv7
	aarch64

Notes about the boot process

Raspberry Pi (all versions)

USB keyboards and HDMI displays work perfectly.

Using the 3.3v serial port via the pin headers (exact location depends on hardware version) will get u-boot output and, when configured, a Linux kernel console.

Troubleshooting

Power issues

Especially with the power-hungry Raspberry Pi 3, it is important to have a sufficient enough power supply or weirdness may happen. Weirdness may include:

• Lightning bolt on HDMI output "breaking" the display.
• Screen switching back to u-boot text
  • Fixable temporarily when power is sufficient by swtiching VT (alt+F2 / alt+F1)
• Random hangs

This problem is a hard problem. It is caused by the Raspberry Pi warning about power issues, but the current drivers (as of Linux 4.14) have a hard time dealing with it properly. If the power supply is rated properly AND the cable is not incurring too much power losses, it may be required to disable the lightning bolt indicator so the display driver isn't messed up. The lightning bolt indicator can be disabled by adding the line avoid_warnings=1 in config.txt

Note: A properly rated USB power supply, AND a good cable are necessary. The cable has to be short enough to not incur power losses through the length. Do note that thin and cheap cables usually have thinner copper wires, which in turn accentuates power losses.

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