Android

Build on Android using Termux

Termux is an Android terminal emulator and Linux environment app (no root required). As of writing, Termux is available experimentally in the Google Play Store; otherwise, it may be obtained directly from the project repo or on F-Droid.

With Termux, you can install and run llama.cpp as if the environment were Linux. Once in the Termux shell:

$ apt update && apt upgrade -y
$ apt install git cmake

Then, follow the build instructions, specifically for CMake.

Once the binaries are built, download your model of choice (e.g., from Hugging Face). It's recommended to place it in the ~/ directory for best performance:

$ curl -L {model-url} -o ~/{model}.gguf

Then, if you are not already in the repo directory, cd into llama.cpp and:

$ ./build/bin/llama-cli -m ~/{model}.gguf -c {context-size} -p "{your-prompt}"

Here, we show llama-cli, but any of the executables under examples should work, in theory. Be sure to set context-size to a reasonable number (say, 4096) to start with; otherwise, memory could spike and kill your terminal.

To see what it might look like visually, here's an old demo of an interactive session running on a Pixel 5 phone:

llama-interactive2.mp4

Cross-compile using Android NDK

It's possible to build llama.cpp for Android on your host system via CMake and the Android NDK. If you are interested in this path, ensure you already have an environment prepared to cross-compile programs for Android (i.e., install the Android SDK). Note that, unlike desktop environments, the Android environment ships with a limited set of native libraries, and so only those libraries are available to CMake when building with the Android NDK (see: https://developer.android.com/ndk/guides/stable_apis.)

Once you're ready and have cloned llama.cpp, invoke the following in the project directory:

$ cmake \
  -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK/build/cmake/android.toolchain.cmake \
  -DANDROID_ABI=arm64-v8a \
  -DANDROID_PLATFORM=android-28 \
  -DCMAKE_C_FLAGS="-march=armv8.7a" \
  -DCMAKE_CXX_FLAGS="-march=armv8.7a" \
  -DGGML_OPENMP=OFF \
  -DGGML_LLAMAFILE=OFF \
  -B build-android

Notes:

While later versions of Android NDK ship with OpenMP, it must still be installed by CMake as a dependency, which is not supported at this time
llamafile does not appear to support Android devices (see: Mozilla-Ocho/llamafile#325)

The above command should configure llama.cpp with the most performant options for modern devices. Even if your device is not running armv8.7a, llama.cpp includes runtime checks for available CPU features it can use.

Feel free to adjust the Android ABI for your target. Once the project is configured:

$ cmake --build build-android --config Release -j{n}
$ cmake --install build-android --prefix {install-dir} --config Release

After installing, go ahead and download the model of your choice to your host system. Then:

$ adb shell "mkdir /data/local/tmp/llama.cpp"
$ adb push {install-dir} /data/local/tmp/llama.cpp/
$ adb push {model}.gguf /data/local/tmp/llama.cpp/
$ adb shell

In the adb shell:

$ cd /data/local/tmp/llama.cpp
$ LD_LIBRARY_PATH=lib ./bin/llama-simple -m {model}.gguf -c {context-size} -p "{your-prompt}"

That's it!

Be aware that Android will not find the library path lib on its own, so we must specify LD_LIBRARY_PATH in order to run the installed executables. Android does support RPATH in later API levels, so this could change in the future. Refer to the previous section for information about context-size (very important!) and running other examples.