raspberry pi in qemu / Romi emulation

README.md

Raspberry pi / Romi in qemu

When working with photonvision and without a romi in front of me, I decided to give qemu a try.

It works, but it is very slow.

See the 'boot' script provided for booting.

Getting Romi 2023 image going.

Romi notes

• system reboots twice before staying up
• first boot runs /usr/lib/raspberrypi-sys-mods/firstboot
• not sure what the second boot does
• third boot stays up.

Get system deps

sudo apt-get install qemu-system-arm cloud-image-utils

Download

Download the image and grab kernel and dtb (device tree) file out.

$ wget https://github.com/wpilibsuite/WPILibPi/releases/download/v2023.1.1/WPILibPi_image-v2023.1.1-Romi.zip
$ unzip WPILibPi_image-v2023.1.1-Romi.zip
$ sudo mount-image-callback --read-only --part=1 \
    WPILibPi-v2023.1.1_2023-01-16-Romi.img -- \
    sh -c \
    'cp -v $MOUNTPOINT/cmdline.txt $MOUNTPOINT/bcm2710-rpi-3-b.dtb $MOUNTPOINT/kernel8.img .'

Boot

Use 'boot' script below. Things to note:

• I took the cmdline from cmdline.txt and adjusted a bit
• I do not think the root=PARTUUID parameter to work although it should have (partition table is MBR and the disk label-id matched the PARTUUID per sfdisk --dump).
• console=ttyAMA0 is what you want for console output.
• Once it is up, you can ssh to localhost port 22, get to guests romi web interface at http://localhost:5580 and photonvision web interface at http://localhost:5800

Links

Just some links to pages that helped me along:

• https://raspberrypi.stackexchange.com/questions/117234
• https://openqa-bites.github.io/posts/2022-04-13-qemu-aarch64/
• https://stackoverflow.com/questions/61562014/qemu-kernel-for-raspberry-pi-3-with-networking-and-virtio-support

boot

#!/bin/sh
boot() {
    local cmdline="console=ttyAMA0 loglevel=8 root=/dev/mmcblk0p2 rootfstype=ext4 fsck.repair=yes rootwait"
    local extra="$1"
    [ $# -ge 1 ] && shift

    local hfwd="hostfwd=tcp::5555-:22"
    hfwd="$hfwd,hostfwd=tcp::5800-:5800"
    hfwd="$hfwd,hostfwd=tcp::5580-:80"

    qemu-system-aarch64 -machine type=raspi3b -m 1024 \
        -nographic \
        -sd disk.img -nographic \
        -kernel kernel8 -dtb ./bcm2710-rpi-3-b-plus.dtb \
        -device usb-net,netdev=net0 \
        -netdev "user,id=net0,$hfwd" \
        -append "$cmdline${extra:+ $extra}" "$@"

}

raw="${1:-WPILibPi-v2023.1.1_2023-01-16-Romi.img}"
first=false
if [ ! -f disk.img ]; then
    qemu-img create -fqcow2 -Fraw -b "$raw" disk.img 8G
    first=true
fi

if [ "$first" = "true" ]; then
    boot init=/usr/lib/raspberrypi-sys-mods/firstboot -no-reboot
    echo "finished first boot"
fi

boot