Comment 11 for bug 1861941

I'm on Focal desktop, running kvm like so

qemu-system-x86_64 -smp 2 -m 1024 --enable-kvm \
  -drive id=disk0,if=none,format=qcow2,file=bionic-bcache-links.qcow2 \
  -device virtio-blk-pci,drive=disk0,bootindex=0 \
  -drive id=disk1,if=none,format=raw,file=bcache1.img \
  -device virtio-blk-pci,drive=disk1 \
  -drive id=disk2,if=none,format=raw,file=bcache2.img \
  -device virtio-blk-pci,drive=disk2 \
  -drive id=cdrom0,if=none,media=cdrom,file=seed.img \
  -device virtio-blk-pci,drive=cdrom0,bootindex=1 \
  -net user,hostfwd=tcp::22222-:22 -net nic,model=virtio \
  -monitor stdio -vnc 0.0.0.0:0 \
  -object rng-random,filename=/dev/urandom,id=rng0 \
  -device virtio-rng-pci,rng=rng0 \
  -serial telnet:localhost:2446,nowait,server

The images are created with:

wget https://cloud-images.ubuntu.com/daily/server/server/bionic/current/bionic-server-cloudimg-amd64.img
qemu-img create -f qcow2 -b bionic-server-cloudimg-amd64.img \
        bionic-bcache-linux.qcow2 20G
qemu-img create -f raw bcache1.img 10G
qemu-img create -f raw bcache2.img 10G

cat <<EOF >user-data
#cloud-config
password: passw0rd
chpasswd: { expire: False }
ssh_pwauth: True
ssh_authorized_keys:
 - |
   <your ssh key here>
EOF

# you'll need cloud-image-utils package installed
cat <<EOF >boot.sh
#!/bin/bash
BOOT=$1
SEED=${2-"seed.img"}
USERDATA=${3-"user-data"}

[ ! -e ${SEED} ] && {
    [ ! -e ${USERDATA} ] && {
        echo "You need a 'user-data' file"
        exit 1;
    }
    [ ! -e meta-data ] && {
         echo "instance-id: $(uuidgen || echo i-abcdefg)" > meta-data
    }
    echo "Creating seed..."
    cloud-localds ${SEED} ${USERDATA} meta-data
}

qemu-system-x86_64 -smp 2 -m 1024 --enable-kvm \
  -drive id=disk0,if=none,format=qcow2,file=${BOOT} \
  -device virtio-blk-pci,drive=disk0,bootindex=0 \
  -drive id=disk1,if=none,format=raw,file=${DISK1} \
  -device virtio-blk-pci,drive=disk1 \
  -drive id=cdrom0,if=none,media=cdrom,file=${SEED} \
  -device virtio-blk-pci,drive=cdrom0,bootindex=1 \
  -net user,hostfwd=tcp::22222-:22 \
  -net nic,model=virtio \
  -monitor stdio \
  -vnc 0.0.0.0:0 \
  -object rng-random,filename=/dev/urandom,id=rng0 \
  -device virtio-rng-pci,rng=rng0 \
  -serial telnet:localhost:2446,nowait,server \
EOF

# watch the server boot with
telnet localhost 2446

# ssh into the instance with
ssh -p 22222 ubuntu@localhost