# How to use the Android NDK to build Arm NN - [Deprecation Notice](#deprecation-notice) - [Introduction](#introduction) - [Prerequisites](#prerequisites) - [Download Arm NN](#download-arm-nn) - [Build Arm Compute Library](#build-arm-compute-library) - [Build Arm NN](#build-arm-nn) - [Build Arm NN Support Library](#build-arm-nn-support-library) - [Build Arm NN Shim](#build-arm-nn-shim) ## Deprecation Notice Arm NN will be dropping support for support library in 24.08. ## Introduction These are step by step instructions for building the Arm NN shim and support library for NNAPI. This work is currently in an experimental phase. ## Prerequisites The following are required to build the Arm NN support library * Android NDK r26b * Detailed setup can be found in [BuildGuideAndroidNDK.md](../BuildGuideAndroidNDK.md) * Flatbuffer version 23.5.26 * Detailed setup can be found in [BuildGuideCrossCompilation.md](../BuildGuideCrossCompilation.md) The following is required to build the Arm NN shim * AOSP Source (Android Open Source Project) * Download the source from the [official website](https://source.android.com/setup/build/downloading) * This guide will use release tag `android12-s1-release` Set environment variables ```bash export WORKING_DIR= export AOSP_ROOT= export AOSP_MODULES_ROOT= export ARMNN_BUILD_DIR= export NDK=android-ndk-r26b export NDK_TOOLCHAIN_ROOT=$NDK/toolchains/llvm/prebuilt/linux-x86_64 export PATH=$NDK_TOOLCHAIN_ROOT/bin/:$PATH export FLATBUFFERS_ANDROID_BUILD= export FLATBUFFERS_X86_BUILD= ``` ## Download Arm NN If the user only wishes to build the Support Library with the NDK, the Arm NN repo can be cloned into any folder. If the user also wishes to build the Arm NN Shim, for this the Arm NN repo will need to reside within the Android tree in order for armnn/shim/Android.bp to be picked up by the Soong (Android) build system. For example $AOSP_ROOT/vendor/arm/armnn * Clone Arm NN: (Requires Git if not previously installed: `sudo apt install git`) ```bash cd $WORKING_DIR git clone https://github.com/ARM-software/armnn.git ``` ## Build Arm Compute Library Arm NN provides a script that downloads the version of Arm Compute Library that Arm NN was tested with: ```bash ${WORKING_DIR}/armnn/scripts/get_compute_library.sh ``` * Build the Arm Compute Library: (Requires SCons if not previously installed: `sudo apt install scons`) ```bash cd ${WORKING_DIR}/clframework scons arch=arm64-v8a \ toolchain_prefix=aarch64-linux-android- \ compiler_prefix=aarch64-linux-android${ANDROID_API}- \ neon=1 opencl=1 \ embed_kernels=1 \ build_dir=android-arm64v8a \ extra_cxx_flags="-Wno-parentheses-equality -Wno-missing-braces -fPIC" \ Werror=0 embed_kernels=1 examples=0 \ validation_tests=0 benchmark_tests=0 benchmark_examples=0 os=android -j16 ``` Note: ANDROID_API is the Android API version you want to build. ## Build Arm NN and Serializer * Build Arm NN: (Requires CMake if not previously installed: `sudo apt install cmake`) ```bash cd $ARMNN_BUILD_DIR CXX=aarch64-linux-android${ANDROID_API}-clang++ \ CC=aarch64-linux-android${ANDROID_API}-clang \ CXX_FLAGS="-fPIE -fPIC" cmake ${WORKING_DIR}/armnn \ -DCMAKE_ANDROID_NDK=$NDK \ -DCMAKE_SYSTEM_NAME=Android \ -DCMAKE_SYSTEM_VERSION=$ANDROID_API \ -DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \ -DCMAKE_EXE_LINKER_FLAGS="-pie -llog -lz" \ -DARMCOMPUTE_ROOT=$WORKING_DIR/clframework/ \ -DARMCOMPUTE_BUILD_DIR=$WORKING_DIR/clframework/build/android-arm64v8a/ \ -DARMCOMPUTENEON=1 -DARMCOMPUTECL=1 -DARMNNREF=1 \ -DFLATBUFFERS_ROOT=$FLATBUFFERS_ANDROID_BUILD \ -DFLATC_DIR=$FLATBUFFERS_X86_BUILD \ -DBUILD_ARMNN_SERIALIZER=1 -DBUILD_GATORD_MOCK=0 -DBUILD_BASE_PIPE_SERVER=0 ``` * Run the build ```bash make -j16 ``` ## Build Arm NN Support Library Building the support library requires building some AOSP libraries via the NDK. It should be possible to use $AOSP_ROOT instead of $AOSP_MODULES_ROOT. However this example will instead clone the necessary AOSP repos outside of the Android tree and apply some minor patches which were required to get it to build with the Android version used in this guide. ```bash # Call a script which will clone the necessary AOSP repos (do not clone them into Android tree) ${WORKING_DIR}/armnn/shim/sl/scripts/clone_aosp_libs.sh $AOSP_MODULES_ROOT # Modify the repos by applying patches ${WORKING_DIR}/armnn/shim/sl/scripts/modify_aosp_libs.sh $AOSP_MODULES_ROOT # Build the Support Library CMARGS="$CMARGS \ -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \ -DANDROID_ABI=arm64-v8a \ -DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \ -DCMAKE_ANDROID_NDK=$NDK \ -DANDROID_PLATFORM=android-$ANDROID_API \ -DAOSP_MODULES_ROOT=$AOSP_MODULES_ROOT \ -DARMNN_SOURCE_DIR=$WORKING_DIR/armnn \ -DArmnn_DIR=$ARMNN_BUILD_DIR " mkdir ${WORKING_DIR}/armnn/shim/sl/build cd ${WORKING_DIR}/armnn/shim/sl/build CXX=aarch64-linux-android$ANDROID_API-clang++ \ CC=aarch64-linux-android$ANDROID_API-clang \ cmake $CMARGS ../ make ``` ## Build Arm NN Shim By default the Arm NN shim Android.bp.off is not enabled. It is enabled below by renaming it to Android.bp ```bash cd ${WORKING_DIR}/armnn/shim mv Android.bp.off Android.bp cd $AOSP_ROOT source build/envsetup.sh lunch -eng cd vendor/arm/armnn/shim export ARMNN_ANDROID_MK_ENABLE=0 mm ``` The built libraries and manifest file can be found here: $AOSP_ROOT/out/target/product//vendor/lib64/libarmnn_support_library.so $AOSP_ROOT/out/target/product//vendor/bin/hw/android.hardware.neuralnetworks-shim-service-armnn $AOSP_ROOT/out/target/product//vendor/etc/vintf/manifest/android.hardware.neuralnetworks-shim-service-armnn.xml Currently the Arm NN libraries are shared libraries and therefore will need to be pushed to the device: $ARMNN_BUILD_DIR/libarmnn.so