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+# Building RetroArch on ArmSoM CM5
+
+This guide builds RetroArch from upstream source on the ArmSoM CM5 development kit using its native Debian 12 XFCE ARM64 image. The tested system had approximately 2 GB of RAM and kernel `6.1.118-rk3576 #198`. RetroArch 1.22.2 was built and tested on October 22, 2026.
+
+You need the development kit and its power supply, an HDMI display, a USB keyboard, and an internet connection. The display must have speakers to test HDMI audio. Run the commands in Bash in a terminal on the board's XFCE desktop, as a regular user with sudo access. Only dependency installation requires sudo.
+
+## Install dependencies
+
+The tested native image already provides the Mali driver and EGL/GLES development files. Keep the image's graphics driver in place.
+
+```bash
+sudo apt-get update
+sudo apt-get -o Dpkg::Use-Pty=0 install -y --no-install-recommends \
+  build-essential git pkg-config curl ca-certificates \
+  libasound2-dev libudev-dev libx11-dev libxext-dev libxinerama-dev \
+  libxrandr-dev libxxf86vm-dev libfreetype6-dev zlib1g-dev libssl-dev \
+  retroarch-assets libretro-core-info
+```
+
+## Download the source
+
+Use a new source directory. These commands select the exact upstream revision used for this test.
+
+```bash
+mkdir -p ~/src
+git clone --depth 1 https://github.com/libretro/RetroArch.git ~/src/RetroArch
+cd ~/src/RetroArch
+git fetch --depth 1 origin a81e450c00745b27ba417d486799b12f09c38ea4
+git checkout --detach FETCH_HEAD
+```
+
+## Build and install
+
+Run each command only after the preceding command succeeds.
+
+```bash
+./configure --prefix="$HOME/.local/retroarch-upstream" \
+  --disable-opengl1 --enable-opengles --enable-opengles3 \
+  --enable-egl --enable-x11 --enable-alsa --enable-udev --enable-ssl \
+  --disable-videocore --disable-vulkan --disable-wayland --disable-kms \
+  --disable-qt --disable-ffmpeg --disable-pulse --disable-jack \
+  --disable-sdl --disable-sdl2
+make -j2
+./retroarch --version
+make install
+```
+
+The build took approximately 15 minutes with two parallel jobs. The executable reported version `1.22.2` and was installed at `~/.local/retroarch-upstream/bin/retroarch`.
+
+## Create the runtime configuration
+
+```bash
+mkdir -p ~/retroarch-source-validation/{config,content,core-package}
+mkdir -p ~/retroarch-source-validation/runtime/{saves,states,system,playlists}
+
+cat > ~/retroarch-source-validation/config/retroarch.cfg <<EOF
+video_driver = "gl"
+video_context_driver = "egl_x"
+video_fullscreen = "true"
+video_windowed_fullscreen = "true"
+video_vsync = "true"
+audio_driver = "alsa"
+audio_device = "plughw:CARD=rockchiphdmi,DEV=0"
+audio_out_rate = "48000"
+audio_latency = "64"
+audio_volume = "-12.0"
+input_driver = "x"
+input_joypad_driver = "udev"
+input_player1_up = "up"
+input_player1_down = "down"
+input_player1_left = "left"
+input_player1_right = "right"
+input_player1_a = "x"
+input_player1_b = "z"
+input_player1_start = "enter"
+input_player1_select = "rshift"
+input_menu_toggle = "f1"
+input_save_state = "f2"
+input_load_state = "f4"
+input_pause_toggle = "p"
+input_exit_emulator = "escape"
+quit_press_twice = "true"
+menu_driver = "ozone"
+core_info_cache_enable = "false"
+config_save_on_exit = "false"
+assets_directory = "/usr/share/libretro/assets"
+libretro_info_path = "/usr/share/libretro/info"
+savefile_directory = "$HOME/retroarch-source-validation/runtime/saves"
+savestate_directory = "$HOME/retroarch-source-validation/runtime/states"
+system_directory = "$HOME/retroarch-source-validation/runtime/system"
+playlist_directory = "$HOME/retroarch-source-validation/runtime/playlists"
+EOF
+```
+
+This configuration uses the native EGL/OpenGL ES graphics stack and the HDMI ALSA device. The tested image did not require `LD_PRELOAD` or an ELD bypass. The ALSA device name in this configuration is specific to this image; use `aplay -L` to check it if you use a different image.
+
+Configuration changes made through the menu are not saved on exit because `config_save_on_exit` is disabled. Edit this file to make persistent changes.
+
+## Download a core and test game
+
+RetroArch is a frontend and needs an emulator core to run content. Here, the Debian Nestopia package is downloaded and extracted without installing the distribution's RetroArch frontend. The core itself is a prebuilt package, not built from source in this guide. The tested package version was `1.52.0+20230102.gitcb1e24e-1`.
+
+Use an empty `core-package` directory so that the package wildcard matches only one file.
+
+```bash
+cd ~/retroarch-source-validation/core-package
+apt-get download libretro-nestopia
+dpkg-deb -x libretro-nestopia_*.deb extracted
+
+cd ~/retroarch-source-validation/content
+curl -fL https://raw.githubusercontent.com/xram64/falling-nes/52dcb8a951200562e696dfc2aba5d4d14edd0078/falling.nes -o Falling.nes
+curl -fL https://raw.githubusercontent.com/xram64/falling-nes/52dcb8a951200562e696dfc2aba5d4d14edd0078/LICENSE -o LICENSE
+echo 'e22b947542c2d7e595bf84725b333be7af8189c5965b9c53e356a249c7d79943  Falling.nes' | sha256sum -c -
+```
+
+The checksum command should print `Falling.nes: OK`. [Falling](https://github.com/xram64/falling-nes) is an open-source homebrew game under the MIT license. Keep its downloaded `LICENSE` when redistributing it.
+
+## Run the game
+
+```bash
+~/.local/retroarch-upstream/bin/retroarch \
+  --config "$HOME/retroarch-source-validation/config/retroarch.cfg" \
+  -L "$HOME/retroarch-source-validation/core-package/extracted/usr/lib/aarch64-linux-gnu/libretro/nestopia_libretro.so" \
+  "$HOME/retroarch-source-validation/content/Falling.nes"
+```
+
+| Key | Action |
+| --- | --- |
+| Enter | Start the game / confirm a menu selection |
+| Left / Right | Move the character |
+| F1 | Open or close the RetroArch menu |
+| Backspace | Go back in the menu |
+| P | Pause / resume |
+| F2 / F4 | Save / load a state |
+| Esc, pressed twice | Exit RetroArch |
+
+After exiting the game, you can launch the menu separately:
+
+```bash
+~/.local/retroarch-upstream/bin/retroarch \
+  --config "$HOME/retroarch-source-validation/config/retroarch.cfg" --menu
+```
+
+## Tested functionality
+
+The source-built frontend was tested with Falling and the Nestopia core: display output, keyboard input, HDMI audio, menu navigation, pause/resume, save/load states, and exiting and relaunching worked. Rendering used the native Mali-G52 EGL/OpenGL ES driver. No RetroArch source changes were needed.
+
+These results apply to the image, revision, and core described above. Reboot recovery, long-term stability, and other cores have not been verified.
diff --git a/mkdocs.yml b/mkdocs.yml
index b6c7784898..42ac8bef02 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -96,6 +96,7 @@ nav:
       - 'Playlists and Thumbnails': 'guides/roms-playlists-thumbnails.md'
       - 'XMB Menu Map': 'guides/xmb-menu-map.md'
     - 'Advanced':
+      - 'ArmSoM CM5': 'guides/armsom-cm5.md'
       - 'AI Service': 'guides/ai-service.md'
       - 'Command-Line Interface (CLI)': 'guides/cli-intro.md'
       - 'CRT SwitchRes': 'guides/crtswitchres.md'