raspi4 looses graphics environment when using nixos-hardware

[mikea]

Display manager claims X11 is up:

$ systemctl status display-manager.service
● display-manager.service - X11 Server
     Loaded: loaded (/etc/systemd/system/display-manager.service; linked; preset: enabled)
     Active: active (running) since Fri 2023-07-07 20:40:43 UTC; 2min 28s ago
    Process: 822 ExecStartPre=/nix/store/gpgkj3fv3ahdr9r67x0cx3gjkm7l9k3d-unit-script-display-manager-pre-start/bin/display-manager-pre-start (code=exited, status=0/SUCCESS)
   Main PID: 827 (lightdm)
         IP: 0B in, 0B out
         IO: 1.3M read, 0B written
      Tasks: 4 (limit: 4448)
        CPU: 67ms
     CGroup: /system.slice/display-manager.service
             └─827 /nix/store/r67fxhilfan54wp64rmwg4pdg0abf3si-lightdm-1.32.0/sbin/lightdm

Jul 07 20:40:43 hamnix systemd[1]: Starting X11 Server...
Jul 07 20:40:43 hamnix systemd[1]: Started X11 Server.

but it is not:

$ ps auxf | grep X
nixos        975  0.0  0.0   6208  2200 pts/0    S+   20:44   0:00              \_ grep X

my config: https://gist.github.com/mikea/084d54c02b68fb28686c78353f1048c9

long discord thread with other people checking in: https://discord.com/channels/568306982717751326/1126377821640605796

[Akiiino]

It looks like it's the kernel that breaks things: setting boot.kernelPackages = pkgs.linuxPackages to override the nixos-hardware's lib.mkDefault pkgs.linuxKernel.packages.linux_rpi4 showed the GUI after a rebuild (though it also caused some new exciting problems).

For completeness, here's my config as well: https://gist.github.com/Akiiino/26681cd2559fa0141b64c2eede582293