Empty log problem when running a simple mini CNN model on Spike

[Nouhaila12-khachtaoui]

Hello,

I am currently working on an academic project where I need to:

Compile a simple CNN model (Convolution + ReLU) written in C to RISC-V.

Run this model using spike with the --log option to analyze the executed instructions (e.g., mul, lw, sw) using spike_log.txt.

Perform optimizations based on the log analysis (energy consumption, latency, memory...).
Context:

• I have successfully executed a Hello World program using Spike + PK, and the output is correctly displayed (Bonjour, RISC-V !).

• I am using SiFive GCC 8.3.0-2019.08.0 toolchain, and Spike compiled from the official repository.

• My simple CNN model compiles and runs successfully on Spike with PK.

Problem: although the execution completes, the spike_log.txt file remains empty (0 lines), even though the terminal shows bbl loader.
Commands used:
riscv64-unknown-elf-gcc -static -march=rv64imac -mabi=lp64 -O0 -o cnn_simple.riscv cnn_simple.c
spike --log=spike_log.txt /usr/local/riscv64-unknown-elf/bin/pk cnn_simple.riscv
grep "mul" spike_log.txt | wc -l
Result:

spike_log.txt is empty.

No instructions (mul, lw, sw) are visible, making any analysis impossible.

Attempts already made:
Tried different toolchain versions (10.2.0 and 8.3.0).

Built and used PK manually.

Tried running in pure bare-metal mode using a link.ld linker script (similar issues).
the links

1. https://github.com/riscv-software-src/riscv-isa-sim
2. https://github.com/riscv-software-src/riscv-pk
3. https://static.dev.sifive.com/dev-tools/freedom-tools/v2020.12/riscv64-unknown-elf-toolchain-10.2.0-2020.12.8-x86_64-linux-ubuntu14.tar.gz
4. https://static.dev.sifive.com/dev-tools/freedom-tools/v2019.08/riscv64-unknown-elf-toolchain-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz

Questions:

1. Is this a known behavior with Spike and PK?
2. Does PK intercept or hide the instruction logs from the user program?
3. Should I consider using Spike in pure bare-metal mode without PK, or using a minimal custom loader?
4. Are there any additional settings needed to enable complete instruction logging during execution?
5. What is the recommended best practice to obtain valid logs from a simple CNN C model running on Spike?

Thank you very much for your support.
Best regards.