Have you by chance tried it out with #191187 ?

Yes, it doesn't build with 5.97 at all. Seems to be running fine so far.

Rebased on latest master.

It's alive!

@K900 Good job! I'm following this thread because I just saw news about Bigscreen releasing soon. It would be great to have it on my RPi to run with the TV :)
Do you know if HDMI-CEC works with this setup?

It links libcec, so it should, I guess? I'm just testing it on my laptop for now. It's also very, VERY barebones.

Result of nixpkgs-review pr 191357 run on x86_64-linux 1

@ofborg eval

FYI I've managed to build a Raspberry Pi image with Bigscreen with this. It boots, but something is not working.

What exactly is "not working"?

I got into journal, found weird errors like this, even though there's plenty of free memory:

Oct 12 12:45:11 nixos-raspi-4 xsession[1106]: DRM_IOCTL_MODE_CREATE_DUMB failed: Cannot allocate memory

and core dumps for kwin_x11 and plasma-remotecontrollers. It might be something specific to RPi though.

Do you have enough memory allocated to CMA?

I followed wiki and set it to 128M in kernelParams. Found out that nixos-hardware sets it properly in device tree. Removed that, now only plasma-remotecontrollers dumped core, and I see some error on TV. It looks like it's related to this in journal:

Oct 12 13:20:52 nixos-raspi-4 xsession[1193]: kf.plasma.quick: QJsonValue(array, QJsonArray(["file:///nix/store/5mzpvpvabg73nwbrzl7051hcc749l2qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen.homescreen/contents/ui/main
.qml:196:13: Type Indicators.KdeConnect unavailable","file:///nix/store/5mzpvpvabg73nwbrzl7051hcc749l2qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen.homescreen/contents/ui/indicators/KdeConnect.qml:15:1: module \"org.kde.kdeconnect\" is not installed"]))

Decoded error from the screen with my phone:

Error loading QML file: file:///nix/store/5mzpvpvabg73nwbrz/7051hc74912qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen. homescreen/contents/ui/main.qmIfiles//nix/store/Smzpvpvabg73nwbrzl7051hcc74912g/-file:///nix/store/5mzpvpvabg73nwbr/7051hc74912qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen.homescreen/contents/ui/indicators/KdeConnect.qml:15:1: module "org.kde.kdeconnect"lsnotinstall
wyeroft.bigscreen.homescreen
• Indicators.Kdeconnect unavailable

Hmm. Can you try also setting programs.kdeconnect.enabled = true;?

I guess, I helped.
Now it says something about volume indicator.

Oct 12 13:40:23 nixos-raspi-4 xsession[2588]: kf.plasma.quick: QJsonValue(array, QJsonArray(["file:///nix/store/5mzpvpvabg73nwbrzl7051hcc749l2qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen.homescreen/contents/ui/main.qml:207:13: Type Indicators.Volume unavailable","file:///nix/store/5mzpvpvabg73nwbrzl7051hcc749l2qm-plasma-bigscreen-5.26.0/share/plasma/plasmoids/org.kde.mycroft.bigscreen.homescreen/contents/ui/indicators/Volume.qml:12:1: module \"org.kde.plasma.private.volume\" is not installed"]))

OK, I think it's time for me to spin up a VM and see what all the dependencies actually are...

OK, added the missing deps now, and a test to make sure nothing like that slips again.

(plasma-remotecontrollers still segfaults though, looks like it might be failing to access /dev/uinput?)

It worked on my Pi as well. It booted into Bigscreen desktop at least. CEC doesn't work though, KDEConnect remote mouse input is freakishly slow, but it booted!

@YorikSar I think I have it mostly figured out, try the latest commit + adding your user to the uinput group.

I've tried your suggestion, CEC still doesn't work, and in general desktop is quite sluggish. I think it's specific to RPi though, so it shouldn't block anything.
Thanks a lot for landing this!

You need kernel 6.0 for graphics acceleration to work on Pi. You're using that, right? Also probably add more CMA.

I've used linuxPackages_rpi4 as recommended in https://nixos.wiki/wiki/NixOS_on_ARM/Raspberry_Pi_4. I didn't look into switching to 6.0 there.
CMA is set to 512M by https://github.com/NixOS/nixos-hardware/blob/master/raspberry-pi/4/modesetting.nix - I tried setting it to 2G, but that didn't work.