Native games: programs built for the console, started without an emulator

buildroot-external/configs/retrostone2_defconfig

@@ -77,6 +77,10 @@ BR2_PACKAGE_MESA3D=y
 BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_LIMA=y
 BR2_PACKAGE_MESA3D_OPENGL_EGL=y
 BR2_PACKAGE_MESA3D_OPENGL_ES=y
+# SDL2 on KMS/DRM + GLES2 and ALSA, for native games (docs/native-games.md)
+BR2_PACKAGE_SDL2=y
+BR2_PACKAGE_SDL2_KMSDRM=y
+BR2_PACKAGE_SDL2_OPENGLES=y
 BR2_PACKAGE_KMSCUBE=y
 
 # Bring-up tools

buildroot-external/configs/retrostone2_release_defconfig

@@ -77,6 +77,10 @@ BR2_PACKAGE_MESA3D=y
 BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_LIMA=y
 BR2_PACKAGE_MESA3D_OPENGL_EGL=y
 BR2_PACKAGE_MESA3D_OPENGL_ES=y
+# SDL2 on KMS/DRM + GLES2 and ALSA, for native games (docs/native-games.md)
+BR2_PACKAGE_SDL2=y
+BR2_PACKAGE_SDL2_KMSDRM=y
+BR2_PACKAGE_SDL2_OPENGLES=y
 BR2_PACKAGE_KMSCUBE=y
 
 # Bring-up tools

docs/native-games.md

@@ -0,0 +1,55 @@
+# Native games
+
+A native game is a program built for the console itself (ARM, Linux), started without an emulator: an
+open-source game engine, a source port, a homebrew game. The menu lists them as the system **Native games**.
+
+## On the SD card
+
+One launch script per game in `roms/native/` (subfolders are fine), with the game's own files next to it:
+
+```
+roms/native/
+  My Game.sh            <- the entry in the menu ("My Game")
+  mygame/
+    mygame              <- the program (ARM, linked against this system's libraries)
+    data files...
+```
+
+The script runs with `/bin/sh` in **its own folder** (the working directory), so it can use relative paths. It
+should end with `exec` so the game is the process the menu watches:
+
+```sh
+#!/bin/sh
+cd mygame
+exec ./mygame
+```
+
+A program that the exFAT partition does not mark executable can be started through the dynamic loader:
+`exec /lib/ld-linux-armhf.so.3 ./mygame`.
+
+## What the game gets
+
+* The display, the sound and the pads, as a libretro game does: the menu drops DRM master before the launch and
+  takes it back afterwards. **SDL2** is installed with the KMS/DRM video driver (GLES2 on the Mali-400 through
+  Mesa's lima) and ALSA; the menu sets `SDL_VIDEODRIVER=kmsdrm` and `SDL_AUDIODRIVER=alsa`.
+* `HOME=/data/rsos/native-home` (the root file system is read-only), with `XDG_CONFIG_HOME` and
+  `XDG_DATA_HOME` under it. A game that saves next to itself (its working directory) keeps its saves on the card.
+* `RSOS_GAME_DIR` (the script's folder) and `RSOS_LANG` (the menu's language, e.g. `en`).
+* Its output goes to `/run/rsos/game.log`, copied to `rsos/logs/` on the SD card at the next start.
+
+The built-in controls are three input devices (the buttons, the shoulder buttons, the optional analog stick):
+a game that reads only one SDL game controller sees only one of them. Read every `/dev/input/event*` device
+whose name starts with "RetroStone2", or merge them.
+
+## What the menu does around it
+
+* **Select + Start** held for one second quits the game (SIGTERM to its process group, SIGKILL if it is still
+  there 5 s later). A native game has no in-game menu of ours.
+* **Sleep** (power key): the game is frozen (SIGSTOP) and the backlight goes off; waking continues it.
+* **Power-off**: the game gets SIGTERM, then SIGKILL after 8 s. There is no save state: the game must save on
+  its own.
+* The **idle power-off** waits while a native game runs (it could not resume it).
+* An exit code other than 0 (and other than a stop by Select+Start or the menu) shows "The game ended with an
+  error".
+
+`make check-frontend` (steps 2a-2c) covers the launch, the environment, the error message and the process group.

frontend/Makefile

@@ -595,6 +595,38 @@ check-frontend: $(FRONTEND) $(HOST_TESTCORE) $(SPLASH)
 	grep -q 'crashed' $(FE_LOG)
 	grep -q 'signal 15: exiting' $(FE_LOG)
 	grep -q 'exit 0 after' $(FE_LOG)
+	@echo "check-frontend: 2a. a native game: its script runs in its folder, HOME on /data, SDL on KMS"
+	@# the native games only: the menu starts on them
+	mv $(FE_CHECK_DIR)/data/roms/nes $(FE_CHECK_DIR)/data/nes.aside
+	rm -f $(FE_CHECK_DIR)/data/rsos/cache/systems.idx
+	printf 'language = en\nlast_system = native\n' > $(FE_SETTINGS)
+	rm -f $(FE_LOG)
+	mkdir -p $(FE_CHECK_DIR)/data/roms/native/files
+	printf 'echo "$$PWD|$$HOME|$$SDL_VIDEODRIVER|$$RSOS_GAME_DIR" > files/ran.txt\nexit $${RSOS_TEST_NATIVE_EXIT:-0}\n' \
+		> "$(FE_CHECK_DIR)/data/roms/native/Native Test.sh"
+	$(FE_RUN) --script "wait:600 a wait:500 a wait:1500 shot:$(FE_CHECK_DIR)/native.png term"
+	grep -q 'launch native Native Test' $(FE_LOG)
+	grep -q 'native game ended: 0' $(FE_LOG)
+	test "$$(cat $(FE_CHECK_DIR)/data/roms/native/files/ran.txt)" = \
+		"$(FE_CHECK_DIR)/data/roms/native|$(FE_CHECK_DIR)/data/rsos/native-home|kmsdrm|$(FE_CHECK_DIR)/data/roms/native"
+	grep -q '^=== \[.*\] launch native: .*Native Test.sh' $(FE_GAME_LOG)
+	@echo "check-frontend: 2b. a native game that fails: its exit code is shown"
+	printf 'language = en\nlast_system = native\n' > $(FE_SETTINGS)
+	rm -f $(FE_LOG)
+	RSOS_TEST_NATIVE_EXIT=3 $(FE_RUN) --script "wait:600 a wait:500 a wait:1500 term"
+	grep -q 'native game ended: 3' $(FE_LOG)
+	@echo "check-frontend: 2c. the menu stops: the native game and what it started go too"
+	printf 'language = en\nlast_system = native\n' > $(FE_SETTINGS)
+	rm -f $(FE_LOG) $(FE_CHECK_DIR)/data/roms/native/files/bg.pid
+	printf 'sleep 300 &\necho $$! > files/bg.pid\nwait\n' > "$(FE_CHECK_DIR)/data/roms/native/Native Test.sh"
+	$(FE_RUN) --script "wait:600 a wait:500 a game:wait:1000 game:term"
+	grep -q 'signal 15: asking the game to quit' $(FE_LOG)
+	grep -q 'native game ended: 143' $(FE_LOG)
+	test -s $(FE_CHECK_DIR)/data/roms/native/files/bg.pid
+	! kill -0 $$(cat $(FE_CHECK_DIR)/data/roms/native/files/bg.pid) 2> /dev/null
+	rm -rf $(FE_CHECK_DIR)/data/roms/native
+	mv $(FE_CHECK_DIR)/data/nes.aside $(FE_CHECK_DIR)/data/roms/nes
+	rm -f $(FE_CHECK_DIR)/data/rsos/cache/systems.idx
 	@echo "check-frontend: 3. charge mode, charger already unplugged: power-off"
 	rm -f $(FE_LOG)
 	printf 'charger\n' > $(FE_CHECK_DIR)/run/rsos/bootreason