RISC-V userspace emulator library

Installing a RISC-V GCC compiler

$ xpm install --global @xpack-dev-tools/riscv-none-embed-gcc@latest

See more here: https://gnu-mcu-eclipse.github.io/install/

Building and running test program

From binaries folder:

$ ./build.sh

Which will produce hello_world in the build folder.

Building the emulator (starting from project root) and booting hello_world:

mkdir -p build
cd build
cmake .. && make -j4
./remu ../binaries/build/hello_world

Building and running your own ELF files that can run in freestanding RV32IM is quite challenging, so consult the hello world example! It's a bit like booting on bare metal using multiboot, except you have easier access to system functions.

Instruction set support

The emulator currently supports RV32IM, however the foundation is laid for RV64IM. Eventually RV32C extension will also be supported (compressed).

Usage

Load a binary and let the machine simulate from _start (ELF entry-point):

#include <libriscv/machine.hpp>

template <int W>
long syscall_exit(riscv::Machine<W>& machine)
{
	printf(">>> Program exit(%d)\n", machine.cpu.reg(riscv::RISCV::REG_ARG0));
	machine.stop();
	return 0;
}

int main(int argc, const char** argv)
{
	const auto binary = <load your RISC-V ELF binary here>;

	riscv::Machine<riscv::RISCV32> machine { binary };
	// install a system call handler
	machine.install_syscall_handler(93, syscall_exit<riscv::RISCV32>);

	while (!machine.stopped())
	{
		machine.simulate();
	}
}

You can find details on the Linux system call ABI online as well as in the syscall.h header in the src folder. You can use this header to make syscalls from your RISC-V programs. It is the Linux RISC-V syscall ABI.

Be careful about modifying registers during system calls, as it may cause problems in the simulated program.