Failed to cross compile with QNN backend

[huangzhiyuan]

Compile with reference to these two documents.

• https://github.com/pytorch/executorch/blob/main/backends/qualcomm/scripts/build.sh
• https://github.com/pytorch/executorch/blob/main/docs/source/build-run-qualcomm-ai-engine-direct-backend.md

The steps I used to reproduce:

mkdir build_cross
cd build_cross

export QNN_SDK_ROOT=the/path/to/qnn/sdk
export EXECUTORCH_ROOT=./executorch
export LD_LIBRARY_PATH=$QNN_SDK_ROOT/lib/x86_64-linux-clang/:$LD_LIBRARY_PATH
export PYTHONPATH=$EXECUTORCH_ROOT/..

cmake .. \
    -DCMAKE_INSTALL_PREFIX=$PWD \
    -DEXECUTORCH_BUILD_QNN=ON \
    -DQNN_SDK_ROOT=$QNN_SDK_ROOT \
    -DEXECUTORCH_BUILD_DEVTOOLS=ON \
    -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
    -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
    -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
    -DPYTHON_EXECUTABLE=python3 \
    -DCMAKE_TOOLCHAIN_FILE=cross_compile.cmake \
    -DEXECUTORCH_SEPARATE_FLATCC_HOST_PROJECT=OFF \
    -B$PWD

cmake --build $PWD -j16 --target install

cross_compile.cmake:

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR aarch64)

set(TOOLCHAIN_ROOT "/opt/toolchains/aarch64-oe-linux-9.3-glibc-2.31")
set(TOOLCHAIN_PREFIX ${TOOLCHAIN_ROOT}/sysroots/x86_64-oesdk-linux/usr/bin/aarch64-oe-linux/aarch64-oe-linux-)
set(CMAKE_C_COMPILER ${TOOLCHAIN_PREFIX}gcc)
set(CMAKE_CXX_COMPILER ${TOOLCHAIN_PREFIX}g++)
set(CMAKE_SYSROOT ${TOOLCHAIN_ROOT}/sysroots/aarch64-oe-linux)
set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -march=armv8-a")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=armv8-a")

error log:

/bin/sh: 1: flatc: not found
backends/qualcomm/CMakeFiles/qcir.dir/build.make:70: recipe for target 'backends/qualcomm/qcir_schema_output' failed
make[2]: *** [backends/qualcomm/qcir_schema_output] Error 127
CMakeFiles/Makefile2:1054: recipe for target 'backends/qualcomm/CMakeFiles/qcir.dir/all' failed
make[1]: *** [backends/qualcomm/CMakeFiles/qcir.dir/all] Error 2
/bin/sh: 1: flatc: not found
backends/qualcomm/CMakeFiles/qnn_schema.dir/build.make:70: recipe for target 'schema/include/executorch/backends/qualcomm/qc_compiler_spec_generated.h' failed
make[2]: *** [schema/include/executorch/backends/qualcomm/qc_compiler_spec_generated.h] Error 127
CMakeFiles/Makefile2:1614: recipe for target 'backends/qualcomm/CMakeFiles/qnn_schema.dir/all' failed
make[1]: *** [backends/qualcomm/CMakeFiles/qnn_schema.dir/all] Error 2
/bin/sh: 1: flatc: not found
devtools/CMakeFiles/bundled_program_schema.dir/build.make:72: recipe for target 'devtools/bundled_program/executorch/devtools/bundled_program/schema/bundled_program_schema_generated.h' failed
make[2]: *** [devtools/bundled_program/executorch/devtools/bundled_program/schema/bundled_program_schema_generated.h] Error 127
CMakeFiles/Makefile2:1804: recipe for target 'devtools/CMakeFiles/bundled_program_schema.dir/all' failed
make[1]: *** [devtools/CMakeFiles/bundled_program_schema.dir/all] Error 2
Makefile:135: recipe for target 'all' failed
make: *** [all] Error 2

but I have added the flatc to $PATH :

$ which flatc
./third-party/flatbuffers/flatc

Any suggestions for this error? thanks~

[kimishpatel]

Can you detail the steps you took to install ExecuTorch?

Another option is to specify flatc localtion via -DFLATC_EXECUTABLE='which flatc like here

executorch/examples/apple/coreml/scripts/build_executor_runner.sh

Line 36 in c86b39d

-DFLATC_EXECUTABLE="$(which flatc)" \

. However, I believe it should not be needed if things are setup correctly