RISC-V Simulator

This repository contains two simulators, a old one in C at the root, and a new one in Rust.

User-Space RISC-V Simulator in Rust

The Rust version can be found here. It works a bit like user-mode QEMU: It simulates a user-space RISC-V binary (currently rv64cim), and when the executable makes a ecall, it translates the syscall number from the RISC-V version to the host version and let's the host kernel execute the syscall. This only works on Linux.

cd ./rust
cargo build

# Example (does two syscalls, a write(2) to stdout, and then a exit(2)):
cat ./tests/examples/hello-world.s

# Build the example:
riscv64-linux-gnu-as ./tests/examples/hello-world.s -o hello-world.o
riscv64-linux-gnu-ld -static hello-world.o -o hello-world.elf

# Run the RISC-V executable:
cargo run -- -f ./hello-world.elf -e

# Build a example using a libc (newlib):
pacman -S extra/riscv64-elf-newlib extra/riscv64-elf-gcc
riscv64-elf-gcc -O1 -static ./tests/examples/hello-world.c -o hello-world.newlib.elf
cargo run -- -f ./hello-world.newlib.elf -e

The rust version is actually capable of running a libc/newlib Hello World program. Only a select few of syscalls are implemented, so you might hit a limit soon. The C version does not support syscalls, only the most basic UART ever.

Be warned that newlib will, before it makes the exit syscall, close stdout. This will close the actual stdout of the simulator process, so that, in verbose mode, you will not see the exit syscall beeing called anymore.

Bare-Metal WASM RISC-V Simulator in C

This project is deployed here (That version is probably not up-to-date though). Everything is still very much work in progress...! The examples in tests/progs all work, you can build them by running make all in that directory. The root Makefile will build a CLI application and the libriscvsim.wasm used by the web-frontend.

Dependencies/Requirements: riscv64-elf-gcc for building the examples and LLVM/clang with a backend and linker for wasm32-unkown-unkown for building the wasm lib. Go look at the Makefile in lib/ if you want to build using another WASM target.

• Features
  • libriscvsim.wasm has no external dependencies at all (Not even libc)
  • Usable via a CLI on x86/ARM/... and in a browser using WebAssembly
• TODOs
  • Be able to decode a lot more instructions
  • Be able to evaluate a lot more instructions
  • Proper UART
  • Make the loader be able to load data and bss sections
  • Step mode for Web-UI
  • Fix bugs (known bugs: lui does not work in WASM?)
• Inspiration
  • c-to-webassembly
  • wasi
  • RISC-V spec (Opcodes: Chap. 19)