Prerequistites

To boot a RISC-V virtual machine you will need the following packages:

• qemu-system-misc - QEMU is used to emulate a virtual RISC-V machine.
• u-boot-qemu - U-Boot is the firmware implementing the UEFI API and loads GRUB.

sudo apt-get update
sudo apt-get install opensbi qemu-system-misc u-boot-qemu

For booting Ubuntu 22.04 (Jammy) or later images use u-boot-qemu from release Ubuntu 22.04 or later.

Booting a preinstalled server image with QEMU

A preinstalled server image can be downloaded from https://cdimage.ubuntu.com/releases/24.04/release/.

First unpack the image

xz -dk ubuntu-24.04-preinstalled-server-riscv64.img.xz

(Up to Ubuntu 22.04. use the image for the SiFive HiFive Unmatched board, e.g. 'ubuntu-22.04.3-preinstalled-server-riscv64+unmatched.img'.)

Optionally, if you want a larger disk, you can expand the disk (the filesystem will be automatically resized too).

qemu-img resize -f raw ubuntu-24.04-preinstalled-server-riscv64.img +5G

Next use u-boot-qemu to boot the virtual machine. A working example with all the options is:

qemu-system-riscv64 \
-machine virt -nographic -m 2048 -smp 4 \
-bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.bin \
-kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf \
-device virtio-net-device,netdev=eth0 -netdev user,id=eth0 \
-device virtio-rng-pci \
-drive file=ubuntu-24.04-preinstalled-server-riscv64.img,format=raw,if=virtio

The important options to use are:

• QEMU's generic virtual platform is selected by -machine virt

• The first stage firmware booted by QEMU is OpenSBI as specified by the -bios option. This option is not needed with QEMU 7.0 or higher. It cannot be used with KVM.

• The second stage firmware U-Boot is loaded into memory via -kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf

One can use pass through networking, adjust memory (-m) & cpu counts (-smp) as needed.

Watch the serial console output and wait for cloud-init to complete. It will show a line with the text 'Cloud-init finished' like:

[   68.346028] cloud-init[703]: Cloud-init v. 22.2-0ubuntu1~20.04.3 finished at Thu, 22 Sep 2022 11:35:28 +0000. Datasource DataSourceNoCloud [seed=/var/lib/cloud/seed/nocloud-net][dsmode=net].  Up 68.26 seconds

Then login using ubuntu:ubuntu. See the cloud-init section below to further customise the first boot behaviour with cloud-init.

cloud-init integration

The image has a fallback cloud-init datasource that configures sudo user ubuntu with password ubuntu and DHCP networking. You will be asked to change the password on first login.

The image has CIDATA partition which can be used as a valid datasource to adjust cloud-config metadata. If you wish to customize user password, networking information, add ssh keys, etc. Please mount CIDATA partition rename meta-data and user-data files and adjust them to taste. You can use network-info to configure networking if something more sophisticated than just DHCP is desired.

For example ssh keys, disabling interactive login, and so on. See https://cloudinit.readthedocs.io/en/latest

Ubuntu installation of a RISC-V virtual machine using a server install image and QEMU

Overview

Starting with Ubuntu 22.04 a server install image for QEMU is available. This topic describes how to use the image for an installation on a virtual machine.

The Jammy release image is available at https://cdimage.ubuntu.com/releases/22.04.3/release/.

Daily build images are provided at https://cdimage.ubuntu.com/ubuntu-server/daily-live/current/.

A general overview of the installation process is available at https://ubuntu.com/tutorials/install-ubuntu-server.

Download the image either using your web browser or with

wget https://cdimage.ubuntu.com/ubuntu-server/daily-live/current/<release>-live-server-riscv64.img.gz 

Installation

Extract the image.

gzip -d jammy-live-server-riscv64.img.gz

Create the disk image on which you will install Ubuntu. 16 GiB should be enough.

dd if=/dev/zero bs=1M of=disk count=1 seek=16383

Start the installer with:

/usr/bin/qemu-system-riscv64 -machine virt -m 4G -smp cpus=2 -nographic \
    -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.bin \
    -kernel /usr/lib/u-boot/qemu-riscv64_smode/u-boot.bin \
    -netdev user,id=net0 \
    -device virtio-net-device,netdev=net0 \
    -drive file=noble-live-server-riscv64.img,format=raw,if=virtio \
    -drive file=disk,format=raw,if=virtio \
    -device virtio-rng-pci

Follow the installation steps in https://ubuntu.com/tutorials/install-ubuntu-server.

When rebooting we have to remove the installer image. Otherwise the installer will restart.

U-Boot gives you a 2 second time window to press the Enter key to reach the U-Boot console. In U-Boot’s console you can use the poweroff command to stop QEMU. Another option to exit QEMU is pressing keys CTRL-a followed by key x.

Run Ubuntu

To run your installed Ubuntu image use

/usr/bin/qemu-system-riscv64 -machine virt -m 4G -smp cpus=2 -nographic \
    -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.bin \
    -kernel /usr/lib/u-boot/qemu-riscv64_smode/u-boot.bin \
    -netdev user,id=net0 \
    -device virtio-net-device,netdev=net0 \
    -drive file=disk,format=raw,if=virtio \
    -device virtio-rng-pci

Limitations

In Ubuntu 22.04 the number of virtual CPUs is limited to 8 in QEMU and in the Linux kernel.