workaround for nvidia dbus errors for nix https://forums.developer.nvidia.com/t/bug-nvidia-v495-29-05-driver-spamming-dbus-enabled-applications-with-invalid-messages/192892/36

nvidiablackhole.nix

{ config, pkgs, ... }:
let
  busName = "nvidia.powerd.server";
  userName = "messagebus";
  nvidiaBlackHole = pkgs.writeTextFile {
    name = "nvidiaBlackHole";
    destination = "/etc/dbus-1/system.d/nvidia-fake-powerd.conf";
    text = ''
      <!DOCTYPE busconfig PUBLIC
       "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
       "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
      <busconfig>
              <policy user="${userName}">
                      <allow own="${busName}"/>
              </policy>
              <policy context="default">
                      <allow send_destination="${busName}"/>
                      <allow receive_sender="${busName}"/>
              </policy>
      </busconfig>
    '';};

in
{
    services.dbus.packages = [nvidiaBlackHole];
    systemd.services.nvidiaBlackHole = {
      wantedBy = [ "default.target" ];
      aliases = ["dbus-nvidia.fake-powerd.service"];
      serviceConfig = {
        Type = "dbus";
        BusName = busName;
        ExecStart = "${pkgs.dbus}/bin/dbus-test-tool black-hole --system --name=${busName}";
        User = userName;
        Group = userName;
        LimitNPROC=2;
        ProtectHome=true;
        ProtectSystem="full";
      };
    };
}

Ah I see - well I misunderstood the assignment haha.