Emulating Raspbian Bullseye with QEMU (arm64, raspi3b) on Ubuntu 22.04 LTS

This guide is a summary of the steps I had to take to emulate Raspbian Bullseye using QEMU, after a lot of online research.

Last tried Jan 2023 on a Lubuntu 22.04 LTS VM

Check the releases page for a ready archive that might save you the hassle.

Prerequisites

• (Recommended) Update your system
  $ sudo apt update && sudo apt upgrade

• Install qemu packages
  $ sudo apt install qemu-system-arm qemu-utils

Disclaimers

• Check your qemu version
  $ qemu-system-arm --version
  This guide uses version 6.2.0. If yours is lower, it may not work for you.

• This guide is for emulating Bullseye Lite (No GUI).
  In theory, it should also work with Bullseye Desktop, but make sure to delete -nographic in the launch command.

• The internet connection within the VM is very slow (~50kB/s while running apt upgrade).
  This guide uses USB as a network interface for the VM.
  If possible, setting up a bridged connection or a NAT interface would probably be better.

• There seems to be a bug which makes it impossible to use virt utils to manage this VM.

• Some steps in the VM's boot sequence fail, but they do not seem to affect functionality.

I honestly do not recommend doing this, but if you insist, good luck.

Steps

1. (Recommended) Create a working dirctory and change to it

• $ sudo mkdir rpidir && cd rpidir

2. Download compressed OS image

• $ wget https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2022-09-26/2022-09-22-raspios-bullseye-armhf-lite.img.xz
• (Or go to the official download page.)

3. Extract OS image

• $ unxz 2022-09-22-raspios-bullseye-armhf-lite.img.xz

4. (Optional) Rename OS image

• $ mv 2022-09-22-raspios-bullseye-armhf-lite.img bullseye.img
  (The rest of this guide assumes it's renamed to bullseye.img)

5. Find out the device offset in the image

• $ fdisk -l bullseye.img
  Sample output:

Disk bullseye.img: 1.75 GiB, 1874853888 bytes, 3661824 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xb1214a26

Device        Boot  Start     End Sectors  Size Id Type
bullseye.img1        8192  532479  524288  256M  c W95 FAT32 (LBA)
bullseye.img2      532480 3661823 3129344  1.5G 83 Linux

• Then multiply the start address of the first device by the the sector size to obtain the offset.
  8192 * 512 = 4194304

6. Create a mount point for the OS image

• $ sudo mkdir /mnt/tmpmnt

7. Mount the OS image at the mount point with the calculated offset

• $ sudo mount -o loop,offset=4194304 bullseye.img /mnt/tmpmnt

8. Copy the kernel from the mounted image

• $ cp /mnt/tmpmnt/kernel8.img kernel.img
  (Renamed to kernel.img for convenience)

9. Copy the dtb from the mounted image

• $ cp /mnt/tmpmnt/bcm2710-rpi-3-b-plus.dtb treeblob.dtb
  (Renamed to treeblob.dtb for convenience)

10. Generate an encrypted password

• $ echo 'password' | openssl passwd -6 -stdin
  (The output of this command is an encrypted version of the password, necessary for the next step)

11. Create and edit userconf.txt file in the mounted image

• $ sudo nano /mnt/tmpmnt/userconf.txt
• Type your crendentials in it, following the format username:encrypted_password.
• Press Ctrl+S to save and Ctrl+X to exit.

12. Unmount the OS image

• $ sudo umount /mnt/tmpmnt

13. Resize the OS image

• $ qemu-img resize bullseye.img 8G
  (You may choose another size, but make sure it's a power of 2 and greater than the initial size)

14. Start the VM using the following command

qemu-system-aarch64 \
	-machine raspi3b \
	-cpu cortex-a72 \
	-smp 4 -m 1G \
	-kernel kernel.img \
	-dtb treeblob.dtb \
	-drive "file=bullseye.img,format=raw,index=0,if=sd" \
	-append "rw earlyprintk loglevel=8 console=ttyAMA0,115200 dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 rootdelay=1" \
	-device usb-net,netdev=net0 -netdev user,id=net0,hostfwd=tcp::5555-:22 \
	-nographic

• Make sure to edit the command according to your files' names.
• (Recommended: save the command as a shell script for easier/faster launch)

It's okay if you don't see anything in the terminal. Just wait. The VM should start booting.
The boot sequence takes a while and some boot steps may fail, but that's probably fine.
Once it's done, you'll be prompted to login. Enter the username and password you specified earlier.
(Note: Some boot messages may keep popping up as you log in.)

Once you're logged in

At this point, the VM is set up and usable. However, it is recommended that you do the following:

1. Resize the main partition to fill the available space

1. Start the cfdisk utility
   

   • $ sudo cfdisk /dev/mmcblk0
     (/dev/mmcblk0 is the device file of the SD card on the Raspberry Pi 3. The cfdisk utility allows us to modify the partitions on the SD card)
   • In the utility, you can use the up and down arrow keys to navigate the partitions, and the side arrow keys to navigate the options.

2. Select the /dev/mmcblk0p2 partition and Resize it to fill the available space.
   (The default given size should be just fine.)

3. Save changes with Write, then Quit.

4. Resize the file system

   • $ sudo resize2fs /dev/mmcblk0p2

5. Shutdown and restart the VM

   • $ sudo shutdown now

2. (Recommended..?) Update the VM's system

• $ sudo apt update && sudo apt upgrade
  (Note: The internet connection within the VM is very slow, and this will take a long time.)

3. Use raspi-config to configure the system

• $ sudo raspi-config
  (This tool enables you to configure your locale, keyboard layout, hostname, password, as well as turn on SSH server, and more)

To access the VM from the host machine using SSH

• Make sure that you have enabled the SSH server through the raspi-config utility.
• $ ssh username@localhost -p 5555
  (5555 being the forward port configured for the VM in the launch command.)
• If you intend to change the VM's ssh server port, make sure to change the forwarded port (from 22) in the launch command as well.

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Sources and additional information

• Emulate Raspberry Pi with QEMU on Azeria-Labs.com.
• Emulating ARM64 Raspberry Pi Image using QEMU (Sep 2022) by Source Meets Sink.
• System emulation using qemu: Raspberry PI 3 (Sep 2022) by Radu Zaharia.
• (Password configuration) An update to Raspberry Pi OS Bullseye (Apr 2022) by Simon Long.
• More sources and information in my Rasbian Buster emulation guide.

Thank you to the linux emulation community, and to the FOSS community as a whole.