Merge pull request 'perf: cut the image 38% and turn GPU acceleration back on' (#112) from perf/gpu-acceleration into dev

Reviewed-on: #112

flake.nix

@@ -53,6 +53,55 @@
         overlays = [ (import rust-overlay) ];
       };
 
+      # Kiosk launcher. The GPU-related Electron flags sit in a shell variable
+      # rather than being baked into ExecStart, so they can be changed on a
+      # running machine by editing /var/lib/bitspire/.env and restarting the
+      # unit. No rebuild, no reboot, and a bad value is one edit away from
+      # being undone — which matters on a box whose screen nobody can see.
+      #
+      # THE DEFAULT IS NOW HARDWARE ACCELERATION.
+      #
+      # From the first ISO commit (19d43c2) until today the kiosk launched with
+      # --disable-gpu AND --disable-software-rasterizer, which turns off GPU
+      # compositing and the SwiftShader fallback together and leaves Chromium
+      # rasterising every pixel on the CPU. Nothing in git ever justified the
+      # pair: no comment, no issue, no commit message. Meanwhile the
+      # descriptive config at /etc/bitspire/config.env claimed
+      # ELECTRON_DISABLE_GPU=false, contradicting the actual command line.
+      #
+      # Tested on sintra 2026-09-24. With the flags removed the GPU process is
+      # stable (zero crashes, zero service restarts) and genuinely on hardware
+      # — /proc/<gpu-pid>/maps shows libgallium, libGLX_mesa and dri_gbm, with
+      # no swrast and no SwiftShader — rendering through crocus on Braswell.
+      # Confirmed by eye on the panel.
+      #
+      # DOURO IS EXEMPT. It keeps the old flags. Bay Trail carries three
+      # separate display workarounds already — a 5.15 kernel pin for an i915
+      # eDP regression, i915.enable_psr=0, and vt.handoff=7 to preserve the
+      # BIOS display init — so it is the most plausible machine for the
+      # original flags to have been a real fix rather than scaffolding. It is
+      # also down pending a reflash, so it cannot be tested. Drop this
+      # exemption once douro is back and accelerates cleanly.
+      #
+      # To override per machine, in /var/lib/bitspire/.env:
+      #   BITSPIRE_ELECTRON_GPU_FLAGS=                             acceleration
+      #   BITSPIRE_ELECTRON_GPU_FLAGS=--disable-gpu                no GPU
+      #   BITSPIRE_ELECTRON_GPU_FLAGS=--use-gl=egl                 force EGL
+      #   (line absent)                                            model default
+      #
+      # Note `-` and not `:-`: an explicitly EMPTY value means "no GPU flags at
+      # all", and must not fall back to the default. Unquoted on purpose so the
+      # value word-splits into argv.
+      mkKioskLauncher = machineModel: atm-app: pkgs.writeShellScript "bitspire-kiosk" ''
+        default_gpu_flags="${
+          if machineModel == "douro" then "--disable-gpu --disable-software-rasterizer" else ""
+        }"
+        exec ${pkgs-unstable.electron}/bin/electron \
+          --no-sandbox --disable-gpu-sandbox --enable-logging \
+          ''${BITSPIRE_ELECTRON_GPU_FLAGS-$default_gpu_flags} \
+          ${atm-app}
+      '';
+
       # Pure ATM app builder (no --impure needed)
       mkAtmApp = import ./nix/mkAtmApp.nix {
         inherit pkgs pkgs-unstable;
@@ -109,6 +158,7 @@
           inherit system;
           specialArgs = {
             inherit pkgs-unstable nixpkgs machineModel atm-app;
+            kioskLauncher = mkKioskLauncher machineModel atm-app;
           };
           modules = [
             ./deploy/nixos/live.nix
@@ -239,6 +289,14 @@
                     VITE_SPIRE_SEED=
                     ELECTRON_FORCE_PROD=1
                     DISPLAY=:0
+                    # Uncomment to change Electron's GPU flags without a
+                    # rebuild, then `systemctl restart bitspire`. An empty
+                    # value means full GPU acceleration; the line being absent
+                    # means the shipped default (GPU and software rasterizer
+                    # both off). Commented rather than set, because a present
+                    # -but-empty value here would silently enable the GPU on
+                    # every machine that regenerates its .env.
+                    # BITSPIRE_ELECTRON_GPU_FLAGS=
                   '' + pkgs.lib.optionalString (config.services.bitspire.relayUrl != "") ''
                     VITE_RELAY_URL=${config.services.bitspire.relayUrl}
                   '' + pkgs.lib.optionalString (config.services.bitspire.lnbitsServerPubkey != "") ''
@@ -254,7 +312,7 @@
                 serviceConfig = {
                   EnvironmentFile = lib.mkForce "/var/lib/bitspire/.env";
                   Environment = "LD_LIBRARY_PATH=${pkgs.stdenv.cc.cc.lib}/lib";
-                  ExecStart = lib.mkForce "${pkgs-unstable.electron}/bin/electron --no-sandbox --disable-gpu-sandbox --disable-gpu --disable-software-rasterizer --enable-logging ${atm-app}";
+                  ExecStart = lib.mkForce "${mkKioskLauncher machineModel atm-app}";
                   MemoryMax = lib.mkForce "1G";
                   NoNewPrivileges = lib.mkForce false;
                   ProtectSystem = lib.mkForce false;