This is a quick way to get RISC-V Linux running in Qemu.

Most modern Linux distrubutions have Qemu packaged, but often the RISC-V version is split into a separate package such as qemu-system-misc, qemu-arch-extra or even qemu-system-riscv.

On MacOS the Qemu is packaged in homebrew and includes RISC-V versions.

To run a Fedora Rawhide type

make rawhide

To run a Debian Sid type

make sid

This will automatically download the needed files from https://esmil.dk/riscv-linux

• fw_jump.bin: OpenSBI early initialization code running in machine mode
• Image: The Linux kernel
• rawhide.qcow2/sid.qcow2: Root filesystem

Once it finishes booting you can either login directly or ssh into it from another terminal using

make ssh

The root password is 123.

Qemu emulates the 3 modes defined in the priviledged spec for RISC-V: machine-, supervisor- and user mode. The Linux kernel is meant to run in supervisor mode, and call into machine mode for a few functions using the Supervisor Binary Interface. OpenSBI implements these functions in machine mode and some early code to set up the machine, switch to supervisor mode and jump to the Linux kernel. This is the -bios fw_jump.bin option to Qemu.

You can cross-compile your own fw_jump.bin using

make opensbi

For this you'll of course need a RISC-V toolchain. Luckily OpenSBI can be compiled both using a toolchain for 'bare metal', usually prefixed with riscv64-unknown-elf-, or a toolchain for Linux, usually prefixed with riscv64-linux-gnu-.

If you have a working RISC-V toolchain it is actually quite easy to cross-compile the Linux kernel. Just enter the Linux source tree and type

make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- defconfig
make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- all

This gives you a working kernel in arch/riscv/boot/Image. However it's a big and generic kernel so it'll take a while to compile. You can build a smaller kernel more specialized for the Qemu virtial machine using the config in this repo:

cp /path/to/riscv-linux/config-virt .config
make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- oldconfig
# optionally configure it further
#make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- nconfig
make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- all

The default kernel this repo downloads is built using this config-virt configuration on the riscv branch in https://github.com/esmil/linux. For now this is the latest stable kernel + the new RISC-V bits that will land in the next release.

The images downloaded are built using the bootstrap.sh script in this repo. These installations are meant to be small and are quite opinionated. As an example they use systemd-networkd to manage the network rather than the usual networkmanager or ifupdown scripts. So don't worry if they feel "alien", it has nothing to do with RISC-V. You can just download the regular but much larger distro-built images directly from the Fedora and Debian sites.

This project is licensed under the BSD 3-Clause license.