Build TFLite Micro for riscv32_mcu

[chuantunglin]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Linux Ubuntu 20.04
• TensorFlow installed from (source or binary): N/A
• TensorFlow version: Tensorflow 2.4.2
• Python version: 3.8.5
• Installed using virtualenv? pip? conda?: N/A
• Bazel version (if compiling from source): N/A
• GCC/Compiler version (if compiling from source): gcc 9.3.0, riscv64-unknown-elf-gcc (GCC) 10.2.0
• CUDA/cuDNN version: N/A
• GPU model and memory: N/A
• Target platform (e.g. Arm Mbed OS, Arduino Nano 33 etc.): RISC-V

Describe the problem
Cannot build TFLite Micro for RISC-V target (TARGET=riscv32_mcu). The error message is shown at the bottom.
The command below doesn't work since the file riscv32_mcu_makefile.inc doesn't exist.
make -f tensorflow/lite/micro/tools/make/Makefile TARGET=riscv32_mcu hello_world

Does anyone successfully build the hello_world example for RISCV (riscv32_mcu)?
What are the exact commands and steps?

Provide the exact sequence of commands / steps that you executed before running into the problem

1. git clone --depth 1 https://github.com/tensorflow/tensorflow.git
2. cd tensorflow
3. vi tensorflow/lite/micro/tools/make/targets/mcu_riscv_makefile.inc
4. change ifeq ($(TARGET), riscv32_mcu) to ifeq ($(TARGET), mcu_riscv)
5. Move two FLAGS (-fno-threadsafe-statics and -fno-use-cxa-atexit) from PLATFORM_FLAGS to CXXFLAGS
6. make -f tensorflow/lite/micro/tools/make/Makefile TARGET=mcu_riscv TARGET_ARCH=riscv32_mcu hello_world

Any other info / logs
Include any logs or source code that would be helpful to diagnose the problem. If including tracebacks, please include the full traceback. Large logs and files should be attached.

$ make -f tensorflow/lite/micro/tools/make/Makefile TARGET=mcu_riscv TARGET_ARCH=riscv32_mcu hello_world
tensorflow/lite/micro/tools/make/downloads/flatbuffers already exists, skipping the download.
tensorflow/lite/micro/tools/make/downloads/pigweed already exists, skipping the download.
tensorflow/lite/micro/tools/make/downloads/person_model_int8 already exists, skipping the download.
riscv64-unknown-elf-g++ -std=c++11 -fno-rtti -fno-exceptions -fno-threadsafe-statics -Werror -fno-unwind-tables -ffunction-sections -fdata-sections -fmessage-length=0 -DTF_LITE_STATIC_MEMORY -DTF_LITE_DISABLE_X86_NEON -O3 -Wsign-compare -Wdouble-promotion -Wshadow -Wunused-variable -Wmissing-field-initializers -Wunused-function -Wswitch -Wvla -Wall -Wextra -Wstrict-aliasing -Wno-unused-parameter -DMCU_RISCV -march=rv32imac -mabi=ilp32 -mcmodel=medany -mexplicit-relocs -fno-builtin-printf -fno-exceptions -DTF_LITE_MCU_DEBUG_LOG -DTF_LITE_USE_GLOBAL_CMATH_FUNCTIONS -fno-unwind-tables -ffunction-sections -fdata-sections -funsigned-char -Wvla -Wall -Wextra -Wsign-compare -Wdouble-promotion -Wshadow -Wunused-variable -Wmissing-field-initializers -Wno-unused-parameter -Wno-write-strings -Wunused-function -fno-delete-null-pointer-checks -fomit-frame-pointer -Os -fpermissive -fno-rtti -fno-threadsafe-statics -fno-use-cxa-atexit --std=gnu++11 -I. -Itensorflow/lite/micro/tools/make/downloads/gemmlowp -Itensorflow/lite/micro/tools/make/downloads/flatbuffers/include -Itensorflow/lite/micro/tools/make/downloads/ruy -Itensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/include -Itensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/drivers/ -Itensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/env -Itensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/env/freedom-e300-hifive1 -Itensorflow/lite/micro/tools/make/downloads/kissfft -o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/bin/hello_world tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/obj/tensorflow/lite/micro/examples/hello_world/main.o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/obj/tensorflow/lite/micro/examples/hello_world/main_functions.o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/obj/tensorflow/lite/micro/examples/hello_world/model.o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/obj/tensorflow/lite/micro/examples/hello_world/output_handler.o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/obj/tensorflow/lite/micro/examples/hello_world/constants.o tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/lib/libtensorflow-microlite.a -Wl,--fatal-warnings -Wl,--gc-sections -Ttensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/env/freedom-e300-hifive1/flash.lds -nostartfiles -Ltensorflow/lite/micro/tools/make/downloads/sifive_fe310_lib/bsp/env --specs=nano.specs -lm
/opt/riscv/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/bin/ld: warning: cannot find entry symbol _start; not setting start address
collect2: error: ld returned 1 exit status
make: *** [tensorflow/lite/micro/examples/hello_world/Makefile.inc:44: tensorflow/lite/micro/tools/make/gen/mcu_riscv_riscv32_mcu_micro/bin/hello_world] Error 1

[ymodak]

I see tf-lite-micro has its own standalone repository now.
I see makefile inside respective example folders.
https://github.com/tensorflow/tflite-micro/blob/main/tensorflow/lite/micro/examples/hello_world/riscv32_mcu/Makefile.inc

[chuantunglin]

Thanks for sharing the link. However, these examples still can't be successfully built for riscv32_mcu in tf-lite-micro's own repository.

If we want to build the example in this repository, are there any steps/commands that work well?

[ymodak]

Closing this issue in the light of tensorflow/tflite-micro#203
Thanks!

[google-ml-butler]

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