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NixOS on ARM/Raspberry Pi 4: Difference between revisions

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!colspan="2" class="title"|Raspberry Pi 4 Family
!colspan="2" class="title"|Raspberry Pi 4 Family
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|colspan="2"|(Image not available)
|colspan="2"|[[File:Raspberry_Pi_4,_2_GB_RAM_version_4.jpg|frameless|256px|A Raspberry Pi 4.]]
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!Manufacturer
!Manufacturer
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</div>
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The Raspberry Pi family of devices is a series of single-board computers made by the Raspberry Pi Foundation. They are all based on Broadcom System-on-a-chip (SOCs).  
The Raspberry Pi family of devices is a series of single-board computers made by the Raspberry Pi Foundation. They are all based on Broadcom System-on-a-chip (SoCs).


== Status ==
== Status ==
{{note|The Raspberry Pi 4 is currently <em>unsupported</em> though the NixOS distribution provides upstream beta-quality images.}}
The default Linux kernel in use, is the Raspberry Pi Foundation's fork. This will change for the mainline kernel once its support for the Raspberry Pi 4 Family is good enough to allow the user to boot, configure, and rebuild a system.


The Raspberry Pi 4 Family is only supported as '''AArch64'''. Use as armv7 is community supported.
The Raspberry Pi 4 Family is only supported as '''AArch64'''. Use as armv7 is community supported.
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First follow the [[NixOS_on_ARM#Installation|generic installation steps]] to get the installer image and install using the [[NixOS_on_ARM#NixOS_installation_.26_configuration|installation and configuration steps]].
First follow the [[NixOS_on_ARM#Installation|generic installation steps]] to get the installer image and install using the [[NixOS_on_ARM#NixOS_installation_.26_configuration|installation and configuration steps]].


Support for the Pi 4 in nixpkgs is still experimental. These configurations will boot (from [https://github.com/NixOS/nixpkgs/pull/68265#issuecomment-532040372 this PR comment]):
The Raspberry Pi 4B works with the [https://hydra.nixos.org/job/nixos/trunk-combined/nixos.sd_image.aarch64-linux generic SD image].
 
Sample instructions for [https://nix.dev/tutorials/installing-nixos-on-a-raspberry-pi installing NixOS on a Raspberry Pi] are available at nix.dev.
 
{{warning| Note that the Raspberry Pi 4 has two HDMI outputs, and apparently sometimes the user prompt for the console/TTY is displayed on HDMI 1 while the boot process is displayed on HDMI 0 (this may even [https://raspberrypi.stackexchange.com/a/112071/149250 be the case] with the official (non NixOs) non-graphical lite image). So if after the message "Welcome on NixOs" at the end of phase 2 your screen goes black/disconnects, try to use the other HDMI port. See the related bug [https://github.com/NixOS/nixpkgs/issues/179701 here].}}


Until the generic image works, a [https://hydra.nixos.org/job/nixos/trunk-combined/nixos.sd_image_raspberrypi4.aarch64-linux temporary device-specific image is build on Hydra]. Note that this image is not using u-boot, but rather the Raspberry Pi specific bootloader configuration.
=== Configuration ===


=== Minimal configuration ===
Using <code>nixos-generate-config</code> will generate the required minimal configuration.


Using <code>nixos-generate-config</code> will not generate the required minimal configuration.
Raspberry Pi 4 is well-supported on modern kernels. However, if you encounter issues with GPU support or other deviceTree quirks, you may wish to add the nixos-hardware channel:
 
<code>
nix-channel --add https://github.com/NixOS/nixos-hardware/archive/master.tar.gz nixos-hardware
 
nix-channel --update
</code>


{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{ pkgs, ... }:
{ config, pkgs, lib, ... }:
 
{
{
   # Assuming this is installed on top of the disk image.
   imports =
  fileSystems = {
     [
     "/boot" = {
       </nowiki><<nowiki>nixos-hardware/raspberry-pi/4</nowiki>><nowiki>
       device = "/dev/disk/by-label/NIXOS_BOOT";
       ./hardware-configuration.nix
       fsType = "vfat";
     ];
     };
  hardware = {
     "/" = {
     raspberry-pi."4".apply-overlays-dtmerge.enable = true;
       device = "/dev/disk/by-label/NIXOS_SD";
    deviceTree = {
       fsType = "ext4";
       enable = true;
       filter = "*rpi-4-*.dtb";
     };
     };
   };
   };
   boot.loader.grub.enable = false;
   console.enable = false;
   boot.loader.raspberryPi.enable = true;
   environment.systemPackages = with pkgs; [
  boot.loader.raspberryPi.version = 4;
    libraspberrypi
  # Mainline doesn't work yet
    raspberrypi-eeprom
  boot.kernelPackages = pkgs.linuxPackages_rpi4;
  ];
  system.stateVersion = "24.11";
}
</nowiki>}}
 
=== <code>config.txt</code> ===
{{warning|Since 24.11, the option <code>boot.loader.raspberrypi</code> which included <code>firmwareConfig</code> is removed from <code>nixpkgs</code>, therefore changes have to be written to <code>config.txt</code> directly<ref>https://github.com/NixOS/nixpkgs/pull/241534</ref>}}
To edit options only available through <code>config.txt</code>, as of May 12, 2025, you can only do so non-declaratively:
 
{{commands|<nowiki>
$ sudo mount /dev/disk/by-label/FIRMWARE /mnt
$ sudo vim /mnt/config.txt # <-- make changes here
</nowiki>}}


  # ttyAMA0 is the serial console broken out to the GPIO
For example, [https://www.raspberrypi-spy.co.uk/2020/11/overclocking-the-raspberry-pi-400/ overclocking] the Raspberry Pi 400 can be done by adding the following:
  boot.kernelParams = [
 
    "console=ttyAMA0,115200"
{{file|config.txt|text|<nowiki>
    "console=tty1"
arm_freq=2000
  ];
over_voltage=6
</nowiki>}}
 
=== USB boot ===
 
For USB booting to work properly, a firmware update might be needed:


  # Required for the Wireless firmware
{{commands|<nowiki>
  hardware.enableRedistributableFirmware = true;
$ nix-shell -p raspberrypi-eeprom
}
$ rpi-eeprom-update -d -a
</nowiki>}}
</nowiki>}}
Now reboot the device so it can update the firmware from the boot partition.


=== GPU support ===
=== GPU support ===
Line 90: Line 115:
   services.xserver = {
   services.xserver = {
     enable = true;
     enable = true;
     displayManager.slim.enable = true;
     displayManager.lightdm.enable = true;
     desktopManager.gnome3.enable = true;
     desktopManager.gnome.enable = true;
     videoDrivers = [ "fbdev" ];
     videoDrivers = [ "fbdev" ];
   };
   };
Line 97: Line 122:
</nowiki>}}
</nowiki>}}
==== With GPU ====
==== With GPU ====
In [https://github.com/NixOS/nixos-hardware/pull/261 nixos-hardware#261] an option has been added to use the <code>fkms-3d</code> ([https://wiki.archlinux.org/title/Kernel_mode_setting modesetting]) overlay which uses the [https://www.raspberrypi.com/news/vc4-and-v3d-opengl-drivers-for-raspberry-pi-an-update/ V3D renderer]. This will only work with the vendor kernel, which is the default in NixOS.
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{ pkgs, ... }:
{ pkgs, ... }:


{
{
   hardware.opengl = {
   imports = [
     enable = true;
     .../nixos-hardware/raspberry-pi/4
    setLdLibraryPath = true;
   ];
    package = pkgs.mesa_drivers;
 
   };
   hardware.raspberry-pi."4".fkms-3d.enable = true;
   hardware.deviceTree = {
 
    base = pkgs.device-tree_rpi;
    overlays = [ "${pkgs.device-tree_rpi.overlays}/vc4-fkms-v3d.dtbo" ];
  };
   services.xserver = {
   services.xserver = {
     enable = true;
     enable = true;
     displayManager.slim.enable = true;
     displayManager.lightdm.enable = true;
     desktopManager.gnome3.enable = true;
     desktopManager.gnome.enable = true;
    videoDrivers = [ "modesetting" ];
   };
   };
  boot.loader.raspberryPi.firmwareConfig = ''
    gpu_mem=192
  '';
}
}
</nowiki>}}
</nowiki>}}


==== Tools ====
=== Tools ===
 
The raspberry tools are available in the <code>libraspberrypi</code> package and include commands like <code>vcgencmd</code> to measure temperature and CPU frequency.
 
=== Audio ===
 
In addition to the usual config, you will need to enable hardware audio support:
 
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{
  # Enable audio devices
  boot.kernelParams = [ "snd_bcm2835.enable_hdmi=1" "snd_bcm2835.enable_headphones=1" ];
}
</nowiki>}}
{{file|config.txt|txt|<nowiki>
dtparam=audio=on
</nowiki>}}
 
If you're running headless, you can also disable HDMI audio and force use of the headphones jack by adding <code>hdmi_ignore_edid_audio=1</code> on a line below <code>dtparam=audio=on</code>.
 
=== Networking ===
 
Ethernet and wifi interfaces should work out of the box. In addition to normal network configuration, consider disabling wifi powersaving if you experience slowness or issues with the host becoming unreachable on the network shortly after boot. For NetworkManager, the following configuration is sufficient:
 
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{
  # Basic networking
  networking.networkmanager.enable = true;
  # Prevent host becoming unreachable on wifi after some time.
  networking.networkmanager.wifi.powersave = false;
}
</nowiki>}}
 
=== Using GPIO pins as non-root ===
 
By default, the GPIO pins are enabled, but can only be accessed by the root user.
This can be addressed by adding a [https://wiki.archlinux.org/title/Udev udev] rule to your configuration that changes the ownership of <code>/dev/gpiomem</code> and the other required devices.
 
The following code adds a group <code>gpio</code> and adds the user <code>mygpiouser</code> to that group. You probably want to put your own user name here.
 
The <code>extraRules</code> changes the owner of <code>gpiomem</code> and all other files needed for GPIO to work to <code>root:gpio</code> and changes the permissions to <code>0660</code>.
Therefore, the root user and anyone in the gpio group can now access the GPIO pins.
 
<syntaxHighlight lang="nix">
  # Create gpio group
  users.groups.gpio = {};
 
  # Change permissions gpio devices
  services.udev.extraRules = ''
    SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio",MODE="0660"
    SUBSYSTEM=="gpio", KERNEL=="gpiochip*", ACTION=="add", RUN+="${pkgs.bash}/bin/bash -c 'chown root:gpio /sys/class/gpio/export /sys/class/gpio/unexport ; chmod 220 /sys/class/gpio/export /sys/class/gpio/unexport'"
    SUBSYSTEM=="gpio", KERNEL=="gpio*", ACTION=="add",RUN+="${pkgs.bash}/bin/bash -c 'chown root:gpio /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value ; chmod 660 /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value'"
  '';
 
  # Add user to group
  users = {
    users.mygpiouser = {
      extraGroups = [ "gpio" ... ];
      ....
    };
  };
</syntaxHighlight>
 
=== Enabling the SPI ===
 
To enable the SPI, you would normally add <code>dtparam=spi=on</code> to <code>/boot/config.txt</code>.
This is not possible on NixOS, and instead you have to apply a device tree overlay.
For this we use the <code>hardware.deviceTree.overlays</code> option.
After applying the overlay, we add an <code>spi</code> group and change the owner of the <code>spidev</code> device to it, similarly to [[#Using GPIO pins as non root |GPIO]].
 
<syntaxhighlight lang="nix">
hardware.raspberry-pi."4".apply-overlays-dtmerge.enable = true;
hardware.deviceTree = {
  enable = true;
  filter = "*-rpi-*.dtb";
  overlays = [
    {
      name = "spi";
      dtboFile = ./spi0-0cs.dtbo;
    }
  ];
};
 
users.groups.spi = {};
 
services.udev.extraRules = ''
  SUBSYSTEM=="spidev", KERNEL=="spidev0.0", GROUP="spi", MODE="0660"
'';
</syntaxhighlight>


The raspberry tools are available in the <code>raspberrypi-tools</code> package and include commands like <code>vcgencmd</code> to measure temperature and CPU frequency.
The the <code>spi0-0cd.dtso</code> file can be downloaded [https://github.com/raspberrypi/firmware/blob/master/boot/overlays/spi0-0cs.dtbo here].
You might have to change the <code>compatible</code> field to "raspberrypi" in the dtbo file.


==== Audio ====
=== HDMI-CEC ===


In addition to the usual config, you will need to enable audio support explicitly in the firmwareConfig.
A few bits and pieces for using HDMI-CEC on the Pi4:


{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
   sound.enable = true;
{ pkgs, ... }:
  hardware.pulseaudio.enable = true;
 
{
  # an overlay to enable raspberrypi support in libcec, and thus cec-client
   nixpkgs.overlays = [
    # nixos-22.05
    # (self: super: { libcec = super.libcec.override { inherit (self) libraspberrypi; }; })
    # nixos-22.11
    (self: super: { libcec = super.libcec.override { withLibraspberrypi = true; }; })
  ];


   boot.loader.raspberryPi.firmwareConfig = ''
   # install libcec, which includes cec-client (requires root or "video" group, see udev rule below)
     dtparam=audio=on
  # scan for devices: `echo 'scan' | cec-client -s -d 1`
  # set pi as active source: `echo 'as' | cec-client -s -d 1`
  environment.systemPackages = with pkgs; [
    libcec
  ];
 
  services.udev.extraRules = ''
     # allow access to raspi cec device for video group (and optionally register it as a systemd device, used below)
    KERNEL=="vchiq", GROUP="video", MODE="0660", TAG+="systemd", ENV{SYSTEMD_ALIAS}="/dev/vchiq"
   '';
   '';
  # optional: attach a persisted cec-client to `/run/cec.fifo`, to avoid the CEC ~1s startup delay per command
  # scan for devices: `echo 'scan' </nowiki>><nowiki> /run/cec.fifo ; journalctl -u cec-client.service`
  # set pi as active source: `echo 'as' </nowiki>><nowiki> /run/cec.fifo`
  systemd.sockets."cec-client" = {
    after = [ "dev-vchiq.device" ];
    bindsTo = [ "dev-vchiq.device" ];
    wantedBy = [ "sockets.target" ];
    socketConfig = {
      ListenFIFO = "/run/cec.fifo";
      SocketGroup = "video";
      SocketMode = "0660";
    };
  };
  systemd.services."cec-client" = {
    after = [ "dev-vchiq.device" ];
    bindsTo = [ "dev-vchiq.device" ];
    wantedBy = [ "multi-user.target" ];
    serviceConfig = {
      ExecStart = ''${pkgs.libcec}/bin/cec-client -d 1'';
      ExecStop = ''/bin/sh -c "echo q </nowiki>><nowiki> /run/cec.fifo"'';
      StandardInput = "socket";
      StandardOutput = "journal";
      Restart="no";
  };
}
</nowiki>}}
</nowiki>}}
=== Enabling Bluetooth ===


== Troubleshooting ==
One might get bluetooth to work with this in the configuration file:
 
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
  systemd.services.btattach = {
    before = [ "bluetooth.service" ];
    after = [ "dev-ttyAMA0.device" ];
    wantedBy = [ "multi-user.target" ];
    serviceConfig = {
      ExecStart = "${pkgs.bluez}/bin/btattach -B /dev/ttyAMA0 -P bcm -S 3000000";
    };
  };
</nowiki>}}
 
== Customizing & Generating SD image without installation step ==
There's a nix-community project to support fine-grained kernel & config.txt, and generate the image directly:
 
[https://github.com/nix-community/raspberry-pi-nix/ nix-community/raspberry-pi-nix]
 
== Notes about the boot process ==
 
Unless using an extremely early WIP image, the Raspberry Pi 4B boots using the U-Boot platform firmware.


=== Power issues ===
=== Updating U-Boot/Firmware ===


The Raspberry Pi 4B is as power-hungry, if not more, as its predecessors. It is important to have a [https://www.raspberrypi.org/documentation/hardware/raspberrypi/power/README.md sufficient enough power supply] or ''weirdness'' may happen. Weirdness may include:
{{commands| <nowiki>
$ nix-shell -p raspberrypi-eeprom
$ sudo mount /dev/disk/by-label/FIRMWARE /mnt
$ sudo BOOTFS=/mnt FIRMWARE_RELEASE_STATUS=stable rpi-eeprom-update -d -a
</nowiki>}} [https://nix.dev/tutorials/installing-nixos-on-a-raspberry-pi#updating-firmware source]


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


{{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.}}
=== Audio not playing and Bluetooth: no controller available ===


Note that the Type-C USB receptacle for the Raspberry Pi 4B '''does not implement Power Delivery (USB PD)'''. This means that it is limited to whatever the power supply will provide when not negotiating power, which is most likely 5V at some undetermined power level.
On the Raspberry Pi kernel, the jack may never play audio, and no Bluetooth devices may ever be found. To get this to work, it is recommended to switch to the mainline kernel. See [https://github.com/NixOS/nixpkgs/issues/123725 nixpkgs#123725] for more info.


<hr />
=== Touch screen not working ===
You have to declare this in your <code>configuration.nix</code><ref>https://discourse.nixos.org/t/cant-get-nixos-x-to-work-on-a-raspberry-pi-with-dsi-display/44532/3</ref>:<syntaxhighlight lang="nix">
hardware.raspberry-pi."4" = {
  touch-ft5406.enable = true;
};
</syntaxhighlight>
Retrieved from "https://wiki.nixos.org/wiki/NixOS_on_ARM/Raspberry_Pi_4"