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<div class="header">
  <div class="headertitle">
<div class="title">How to Cross-Compile Arm NN on x86_64 for arm64 </div>  </div>
</div><!--header-->
<div class="contents">
<div class="textblock"><ul>
<li><a href="#introduction">Introduction</a></li>
<li><a href="#cross-compiling-toolchain">Cross-compiling ToolChain</a></li>
<li><a href="#build-cmake">Install Cmake</a></li>
<li><a href="#build-and-install-google-s-protobuf-library">Build and install Google's Protobuf library</a></li>
<li><a href="#download-arm-nn">Download Arm NN</a></li>
<li><a href="#build-arm-compute-library">Build Arm Compute Library</a></li>
<li><a href="#build-flatbuffer">Build Flatbuffer</a></li>
<li><a href="#build-onnx">Build Onnx</a></li>
<li><a href="#build-tflite">Build TfLite</a></li>
<li><a href="#build-armnn">Build Arm NN</a></li>
<li><a href="#generate-tflite-schema">Generate TF Lite Schema</a></li>
<li><a href="#build-standalone-sample-dynamic-backend">Build Standalone Sample Dynamic Backend</a></li>
<li><a href="#run-unit-tests">Run Unit Tests</a></li>
<li><a href="#troubleshooting-and-errors-">Troubleshooting and Errors:</a></li>
</ul>
<h2>Introduction</h2>
<p>These are the step by step instructions on Cross-Compiling Arm NN under an x86_64 system to target an Arm64 system. This build flow has been tested with Ubuntu 18.04 and 20.04 and it depends on the same version of Ubuntu or Debian being installed on both the build host and target machines. The instructions assume you are using a bash shell and show how to build the Arm NN core library, Protobuf, Tflite, Flatbuffer and Compute Libraries. Start by creating a directory to contain all components:</p>
<p>''' mkdir $HOME/armnn-devenv cd $HOME/armnn-devenv '''</p>
<h2>Cross-compiling ToolChain</h2>
<ul>
<li>Install the standard cross-compilation libraries for arm64: <div class="fragment"><div class="line">sudo apt install crossbuild-essential-arm64</div></div><!-- fragment --></li>
</ul>
<h2>Install Cmake</h2>
<p>Cmake 3.19rc3 is required to build TF Lite Delegate.</p>
<p>''' sudo apt-get install libssl-dev wget <a href="https://github.com/Kitware/CMake/releases/download/v3.19.0-rc3/cmake-3.19.0-rc3.tar.gz">https://github.com/Kitware/CMake/releases/download/v3.19.0-rc3/cmake-3.19.0-rc3.tar.gz</a> tar -zxvf cmake-3.19.0-rc3.tar.gz cd cmake-3.19.0-rc3 ./bootstrap &ndash;prefix=$HOME/armnn-devenv/cmake/install make all install cd.. '''</p>
<h2>Build and install Google's Protobuf library</h2>
<p>We support protobuf version 3.12.0</p><ul>
<li>Get protobuf from here: <a href="https://github.com/protocolbuffers/protobuf:">https://github.com/protocolbuffers/protobuf:</a> (Requires Git if not previously installed: <code>sudo apt install git</code>) <div class="fragment"><div class="line">git clone -b v3.12.0 https://github.com/google/protobuf.git protobuf</div><div class="line">cd protobuf</div><div class="line">git submodule update --init --recursive</div><div class="line">./autogen.sh</div></div><!-- fragment --></li>
<li>Build a native (x86_64) version of the protobuf libraries and compiler (protoc): (Requires cUrl, autoconf, llibtool, and other build dependencies if not previously installed: sudo apt install curl autoconf libtool build-essential g++) <div class="fragment"><div class="line">mkdir x86_64_build</div><div class="line">cd x86_64_build</div><div class="line">../configure --prefix=$HOME/armnn-devenv/google/x86_64_pb_install</div><div class="line">make install -j16</div><div class="line">cd ..</div></div><!-- fragment --></li>
<li>Build the arm64 version of the protobuf libraries: <div class="fragment"><div class="line">mkdir arm64_build</div><div class="line">cd arm64_build</div><div class="line">CC=aarch64-linux-gnu-gcc \</div><div class="line">CXX=aarch64-linux-gnu-g++ \</div><div class="line">../configure --host=aarch64-linux \</div><div class="line">--prefix=$HOME/armnn-devenv/google/arm64_pb_install \</div><div class="line">--with-protoc=$HOME/armnn-devenv/google/x86_64_pb_install/bin/protoc</div><div class="line">make install -j16</div><div class="line">cd ..</div></div><!-- fragment --></li>
</ul>
<h2>Download Arm NN</h2>
<ul>
<li>Clone Arm NN: <div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">git clone https://github.com/ARM-software/armnn.git</div></div><!-- fragment --></li>
<li>Checkout Arm NN branch: <div class="fragment"><div class="line">cd armnn</div><div class="line">git checkout &lt;branch_name&gt;</div><div class="line">git pull</div></div><!-- fragment --> For example, if you want to check out the 21.11 release branch: <div class="fragment"><div class="line">git checkout branches/armnn_21_11</div><div class="line">git pull</div></div><!-- fragment --></li>
</ul>
<h2>Build Arm Compute Library</h2>
<ul>
<li>Clone Arm Compute Library:</li>
</ul>
<div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">git clone https://github.com/ARM-software/ComputeLibrary.git</div></div><!-- fragment --><ul>
<li>Checkout Arm Compute Library release tag: <div class="fragment"><div class="line">cd ComputeLibrary</div><div class="line">git checkout &lt;tag_name&gt;</div></div><!-- fragment --> Arm NN and Arm Compute Library are developed closely together. If you would like to use the Arm NN 21.11 release you will need the 21.11 release of ACL too. For example, if you want to checkout the 21.11 release tag: <div class="fragment"><div class="line">git checkout v21.11</div></div><!-- fragment --> Arm NN provides a script that downloads the version of Arm Compute Library that Arm NN was tested with: <div class="fragment"><div class="line">git checkout $(../armnn/scripts/get_compute_library.sh -p) </div></div><!-- fragment --></li>
<li>Build the Arm Compute Library: (Requires SCons if not previously installed: <code>sudo apt install scons</code>) <div class="fragment"><div class="line">scons arch=arm64-v8a neon=1 opencl=1 embed_kernels=1 extra_cxx_flags=&quot;-fPIC&quot; -j4</div></div><!-- fragment --></li>
</ul>
<h2>Build Flatbuffer</h2>
<ul>
<li>Building Flatbuffer version 1.12.0 <div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">wget -O flatbuffers-1.12.0.tar.gz https://github.com/google/flatbuffers/archive/v1.12.0.tar.gz</div><div class="line">tar xf flatbuffers-1.12.0.tar.gz</div><div class="line">cd flatbuffers-1.12.0</div><div class="line">rm -f CMakeCache.txt</div><div class="line">mkdir build</div><div class="line">cd build</div><div class="line">cmake .. -DFLATBUFFERS_BUILD_FLATC=1 \</div><div class="line">     -DCMAKE_INSTALL_PREFIX:PATH=$HOME/armnn-devenv/flatbuffers \</div><div class="line">     -DFLATBUFFERS_BUILD_TESTS=0</div><div class="line">make all install</div></div><!-- fragment --></li>
<li>Build arm64 version of flatbuffer <div class="fragment"><div class="line">cd ..</div><div class="line">mkdir build-arm64</div><div class="line">cd build-arm64</div><div class="line"># Add -fPIC to allow us to use the libraries in shared objects.</div><div class="line">CXXFLAGS=&quot;-fPIC&quot; cmake .. -DCMAKE_C_COMPILER=/usr/bin/aarch64-linux-gnu-gcc \</div><div class="line">     -DCMAKE_CXX_COMPILER=/usr/bin/aarch64-linux-gnu-g++ \</div><div class="line">     -DFLATBUFFERS_BUILD_FLATC=1 \</div><div class="line">     -DCMAKE_INSTALL_PREFIX:PATH=$HOME/armnn-devenv/flatbuffers-arm64 \</div><div class="line">     -DFLATBUFFERS_BUILD_TESTS=0</div><div class="line">make all install</div></div><!-- fragment --></li>
</ul>
<h2>Build Onnx</h2>
<ul>
<li>Building Onnx <div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">git clone https://github.com/onnx/onnx.git</div><div class="line">cd onnx</div><div class="line">git fetch https://github.com/onnx/onnx.git 553df22c67bee5f0fe6599cff60f1afc6748c635 &amp;&amp; git checkout FETCH_HEAD</div><div class="line">LD_LIBRARY_PATH=$HOME/armnn-devenv/google/x86_64_pb_install/lib:$LD_LIBRARY_PATH \</div><div class="line">$HOME/armnn-devenv/google/x86_64_pb_install/bin/protoc \</div><div class="line">onnx/onnx.proto --proto_path=. --proto_path=../google/x86_64_pb_install/include --cpp_out $HOME/armnn-devenv/onnx</div></div><!-- fragment --></li>
</ul>
<h2>Build TfLite</h2>
<ul>
<li>Arm NN provides a script, armnn/scripts/get_tensorflow.sh, that can be used to check out the version of TensorFlow that Arm NN was tested with: <div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">git clone https://github.com/tensorflow/tensorflow.git</div><div class="line">cd tensorflow/</div><div class="line">git checkout $(../armnn/scripts/get_tensorflow.sh -p) # Checks out the latest tested version of TF</div><div class="line">cd ..</div></div><!-- fragment --></li>
<li>You will need to download gcc-arm-8.3-2019.03 toolchain and continue building TF Lite as following: <div class="fragment"><div class="line">curl -LO https://storage.googleapis.com/mirror.tensorflow.org/developer.arm.com/media/Files/downloads/gnu-a/8.3-2019.03/binrel/gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu.tar.xz</div><div class="line">mkdir tflite-toolchains</div><div class="line">tar xvf gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu.tar.xz -C tflite-toolchains</div><div class="line">mkdir tflite/build</div><div class="line">cd tflite/build</div><div class="line">ARMCC_PREFIX=$HOME/armnn-devenv/tflite-toolchains/gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu/bin/aarch64-linux-gnu- \</div><div class="line">ARMCC_FLAGS=&quot;-funsafe-math-optimizations&quot; \</div><div class="line">cmake -DCMAKE_C_COMPILER=${ARMCC_PREFIX}gcc \</div><div class="line">      -DCMAKE_CXX_COMPILER=${ARMCC_PREFIX}g++ \</div><div class="line">      -DCMAKE_C_FLAGS=&quot;${ARMCC_FLAGS}&quot; -DCMAKE_CXX_FLAGS=&quot;${ARMCC_FLAGS}&quot; \</div><div class="line">      -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON  -DCMAKE_SYSTEM_NAME=Linux \</div><div class="line">      -DTFLITE_ENABLE_XNNPACK=OFF \</div><div class="line">      -DCMAKE_SYSTEM_PROCESSOR=aarch64 \</div><div class="line">      $HOME/armnn-devenv/tensorflow/tensorflow/lite/ \</div><div class="line">cmake --build .</div></div><!-- fragment --></li>
</ul>
<p>## Generate TF Lite Schema </p><div class="fragment"><div class="line">cd $HOME/armnn-devenv</div><div class="line">cp ../tensorflow/tensorflow/lite/schema/schema.fbs .</div><div class="line">../flatbuffers-1.12.0/build/flatc -c --gen-object-api --reflect-types --reflect-names schema.fbs</div></div><!-- fragment --><h2>Build Arm NN</h2>
<ul>
<li>Compile Arm NN for arm64: <div class="fragment"><div class="line">cd $HOME/armnn-devenv/armnn</div><div class="line">mkdir build</div><div class="line">cd build</div></div><!-- fragment --></li>
<li>Use CMake to configure your build environment, update the following script and run it from the armnn/build directory to set up the Arm NN build: <div class="fragment"><div class="line">#!/bin/bash</div><div class="line">CXX=aarch64-linux-gnu-g++ CC=aarch64-linux-gnu-gcc cmake .. \</div><div class="line">-DARMCOMPUTE_ROOT=$HOME/armnn-devenv/ComputeLibrary \</div><div class="line">-DARMCOMPUTE_BUILD_DIR=$HOME/armnn-devenv/ComputeLibrary/build/ \</div><div class="line">-DARMCOMPUTENEON=1 -DARMCOMPUTECL=1 -DARMNNREF=1 \</div><div class="line">-DONNX_GENERATED_SOURCES=$HOME/armnn-devenv/onnx \</div><div class="line">-DBUILD_ONNX_PARSER=1 \</div><div class="line">-DBUILD_TF_LITE_PARSER=1 \</div><div class="line">-DTENSORFLOW_ROOT=$HOME/armnn-devenv/tensorflow \</div><div class="line">-DFLATBUFFERS_ROOT=$HOME/armnn-devenv/flatbuffers-arm64 \</div><div class="line">-DFLATC_DIR=$HOME/armnn-devenv/flatbuffers-1.12.0/build \</div><div class="line">-DPROTOBUF_ROOT=$HOME/armnn-devenv/google/x86_64_pb_install \</div><div class="line">-DPROTOBUF_ROOT=$HOME/armnn-devenv/google/x86_64_pb_install/ \</div><div class="line">-DPROTOBUF_LIBRARY_DEBUG=$HOME/armnn-devenv/google/arm64_pb_install/lib/libprotobuf.so.23.0.0 \</div><div class="line">-DPROTOBUF_LIBRARY_RELEASE=$HOME/armnn-devenv/google/arm64_pb_install/lib/libprotobuf.so.23.0.0</div></div><!-- fragment --></li>
<li>If you want to include standalone sample dynamic backend tests, add the argument to enable the tests and the dynamic backend path to the CMake command: <div class="fragment"><div class="line">-DSAMPLE_DYNAMIC_BACKEND=1 \</div><div class="line">-DDYNAMIC_BACKEND_PATHS=$SAMPLE_DYNAMIC_BACKEND_PATH</div></div><!-- fragment --></li>
<li>If you want to build Arm NN TF Lite Delegate, add the arguments: <div class="fragment"><div class="line">-DTFLITE_LIB_ROOT=$HOME/armnn-devenv/tflite/build \</div><div class="line">-DTF_LITE_SCHEMA_INCLUDE_PATH=$HOME/armnn-devenv/tflite \</div><div class="line">-DBUILD_ARMNN_TFLITE_DELEGATE=1</div></div><!-- fragment --></li>
<li>Run the build <div class="fragment"><div class="line">make -j32</div></div><!-- fragment --></li>
</ul>
<h2>Build Standalone Sample Dynamic Backend</h2>
<ul>
<li>The sample dynamic backend is located in armnn/src/dynamic/sample <div class="fragment"><div class="line">cd $HOME/armnn-devenv/armnn/src/dynamic/sample</div><div class="line">mkdir build</div><div class="line">cd build</div></div><!-- fragment --></li>
<li>Use CMake to configure your build environment, update the following script and run it from the armnn/src/dynamic/sample/build directory to set up the Arm NN build: <div class="fragment"><div class="line">#!/bin/bash</div><div class="line">CXX=aarch64-linux-gnu-g++ CC=aarch64-linux-gnu-gcc cmake .. \</div><div class="line">-DCMAKE_CXX_FLAGS=--std=c++14 \</div><div class="line">-DARMNN_PATH=$HOME/armnn-devenv/armnn/build/libarmnn.so</div></div><!-- fragment --></li>
<li>Run the build <div class="fragment"><div class="line">make</div></div><!-- fragment --></li>
</ul>
<h2>Run Unit Tests</h2>
<ul>
<li>Copy the build folder to an arm64 linux machine</li>
<li>Copy the libprotobuf.so.23.0.0 library file to the build folder</li>
<li>If you enable the standalone sample dynamic tests, also copy libArm_SampleDynamic_backend.so library file to the folder specified as $SAMPLE_DYNAMIC_BACKEND_PATH when you build Arm NN</li>
<li>cd to the build folder on your arm64 machine and set your LD_LIBRARY_PATH to its current location:</li>
</ul>
<div class="fragment"><div class="line">cd build/</div></div><!-- fragment --><ul>
<li>Create a symbolic link to libprotobuf.so.23.0.0:</li>
</ul>
<div class="fragment"><div class="line">ln -s libprotobuf.so.23.0.0 ./libprotobuf.so.23</div></div><!-- fragment --><ul>
<li>Run the UnitTests:</li>
</ul>
<div class="fragment"><div class="line">LD_LIBRARY_PATH=./:$LD_LIBRARY_PATH ./UnitTests</div><div class="line">[doctest] doctest version is &quot;2.4.6&quot;</div><div class="line">[doctest] run with &quot;--help&quot; for options</div><div class="line">===============================================================================</div><div class="line">[doctest] test cases:   4817 |   4817 passed | 0 failed | 0 skipped</div><div class="line">[doctest] assertions: 807634 | 807634 passed | 0 failed |</div><div class="line">[doctest] Status: SUCCESS!</div></div><!-- fragment --><ul>
<li>Run the Delegate UnitTests:</li>
</ul>
<div class="fragment"><div class="line">LD_LIBRARY_PATH=./:$LD_LIBRARY_PATH ./delegate/DelegateUnitTests</div></div><!-- fragment --><h2>Troubleshooting and Errors:</h2>
<h3>Missing libz.so.1</h3>
<ul>
<li>When compiling armNN: <div class="fragment"><div class="line">/usr/lib/gcc-cross/aarch64-linux-gnu/5/../../../../aarch64-linux-gnu/bin/ld: warning: libz.so.1, needed by /home/&lt;username&gt;/armNN/usr/lib64/libprotobuf.so.23.0.0, not found (try using -rpath or -rpath-link)</div></div><!-- fragment --></li>
<li>Missing arm64 libraries for libz.so.1, these can be added by adding a second architecture to dpkg and explicitly installing them: <div class="fragment"><div class="line">sudo dpkg --add-architecture arm64</div><div class="line">sudo apt-get install zlib1g:arm64</div><div class="line">sudo apt-get update</div><div class="line">sudo ldconfig</div></div><!-- fragment --></li>
<li>If apt-get update returns 404 errors for arm64 repos refer to section 5 below.</li>
<li>Alternatively the missing arm64 version of libz.so.1 can be downloaded and installed from a .deb package here: <a href="https://launchpad.net/ubuntu/wily/arm64/zlib1g/1:1.2.8.dfsg-2ubuntu4">https://launchpad.net/ubuntu/wily/arm64/zlib1g/1:1.2.8.dfsg-2ubuntu4</a> <div class="fragment"><div class="line">sudo dpkg -i zlib1g_1.2.8.dfsg-2ubuntu4_arm64.deb</div></div><!-- fragment --> <br />
<br />
</li>
</ul>
<h3>Unable to install arm64 packages after adding arm64 architecture</h3>
<ul>
<li>Using sudo apt-get update should add all of the required repos for arm64 but if it does not or you are getting 404 errors the following instructions can be used to add the repos manually:</li>
<li>From stackoverflow: <a href="https://askubuntu.com/questions/430705/how-to-use-apt-get-to-download-multi-arch-library/430718">https://askubuntu.com/questions/430705/how-to-use-apt-get-to-download-multi-arch-library/430718</a></li>
<li>Open /etc/apt/sources.list with your preferred text editor.</li>
<li>Mark all the current (default) repos as [arch=&lt;current_os_arch&gt;], e.g. <div class="fragment"><div class="line">deb [arch=amd64] http://archive.ubuntu.com/ubuntu/ xenial main restricted</div></div><!-- fragment --></li>
<li>Then add the following: <div class="fragment"><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial main restricted</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial-updates main restricted</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial universe</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial-updates universe</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial multiverse</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial-updates multiverse</div><div class="line">deb [arch=arm64] http://ports.ubuntu.com/ xenial-backports main restricted universe multiverse</div></div><!-- fragment --></li>
<li>Update and install again: <div class="fragment"><div class="line">sudo apt-get install zlib1g:arm64</div><div class="line">sudo apt-get update</div><div class="line">sudo ldconfig</div></div><!-- fragment --> <br />
<br />
</li>
</ul>
<h3>Undefined references to google::protobuf:: functions</h3>
<ul>
<li>Missing or out of date protobuf compilation libraries. Use the command 'protoc &ndash;version' to check which version of protobuf is available (version 3.12.0 is required). Follow the instructions above to install protobuf 3.12.0 <br />
<br />
</li>
</ul>
<h3>Errors on strict-aliasing rules when compiling the Compute Library</h3>
<ul>
<li>When compiling the Compute Library there are multiple errors on strict-aliasing rules: <div class="fragment"><div class="line">cc1plus: error: unrecognized command line option ‘-Wno-implicit-fallthrough’ [-Werror]</div></div><!-- fragment --></li>
<li>Add Werror=0 to the scons command: <div class="fragment"><div class="line">scons arch=arm64-v8a neon=1 opencl=1 embed_kernels=1 extra_cxx_flags=&quot;-fPIC&quot; -j8 Werror=0</div></div><!-- fragment --> </li>
</ul>
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