docker-qemu-riscv

🛠️ Docker image with QEMU configured for RISC-V emulation. Perfectly suited for cross-debugging RISC-V.

Problem

I created this image while I was developing cryptographic optimizations of know algorithms for RISC-V. I installed the riscv-gnu-toolchain in my MacBook Pro M1 using brew install riscv-tools. While I succeed installing the cross-compilation toolchain, I couldn't achieve cross-debugging with QEMU in Apple Silicon (building the source didn't work).

Solution

Docker image based on Ubuntu with QEMU configured for RISC-V emulation (both system and user space).

Tools included

• qemu-system-riscv32: System emulation of RISC-V 32 bits;
• qemu-system-riscv64: System emulation of RISC-V 64 bits;
• qemu-riscv32: User space emulation of RISC-V 32 bits;
• qemu-riscv64: User space emulation of RISC-V 64 bits;

Roadmap

1. QEMU for RISC-V for cross debugging
2. riscv-gnu-toolchain for cross-compilation

Cross-debugging example

This image is very useful to create a light linux VM for cross-debugging RISC-V, using qemu and gdb (the gdb required is the one installed together with riscv-gnu-toolchain). The example/ folder in this repo contain a simple C code used this tutorial:

1. Cross-compile your C code for debugging:

riscv64-unknown-elf-gcc example/main.c -static -o -g main.elf

2. Run the qemu-riscv container sharing the directory the code is being built as a volume, port mapping the port `1234``, and, run bash thru it:

docker run --name=qemu-riscv -dit -v $(pwd):/root -p 1234:1234 paulopacitti/qemu-riscv:latest
docker exec -it qemu-riscv bash

3. Inside the container, run QEMU in debug mode with the -g flag in port 1234 passing your the ELF built:

qemu-riscv64 -g 1234 /root/main.elf

4. While QEMU is hanging, in your local machine run gdb from the riscv-gnu-toolchain:

riscv64-unknown-elf-gdb main.elf

5. Add breaks, enable features and then add the container as a remoter target:

(gdb) b main
(gdb) tui enable
(gdb) tui reg all
(gdb) target extended-remote :1234

6. Now you can debug with gdb as you normally would :)