What are the installed defaults and configuration settings?

Our aim is produced an image as close as possible to a plain, basic Debian install. That is, we don’t provide an image preloaded with a desktop environment, programming tools, enabled services, nor any other niceties. You get a simple Debian system, as close as possible as we believe you can get to what d-i would yield.

Of course, due to the media being different, there are some differences. We will try to list them all here; for further details on the specific adequation steps, you might be interested in looking at our master vmdb2 image builder spec.

Default settings

Partitioning: The image ships as a 1500MB media, which means you can use it in any device of that size or greater. The first 300MB will be set aside as a boot partition. The image will resize to use all of the available space on the first boot — If you want it not to span the SD’s full size, after flashing it to your SD card, you can use fdisk to create a limiting dummy partition at the limit you want to set. After the first boot, just delete (or use!) that partition; the auto-resizer will not be run again.
Root password: Controversial as it is, we decided to ship the images with an empty root password. That means, you will be able to log in as root locally (not through the network) without providing a password. We believe this matches the most common use cases of Raspberries. Of course, you are encouraged to set a root password as soon as possible (specially if your device is to have any kind of network connectivity!)
Installed packages: Additionally to a bare Debian base install, you will find:
- Necessary packages for this platform to work: raspi3-firmware (from non-free ☹; renamed to raspi-firmware after Buster and in buster-backports, already installed on the Raspberry Pi 4 images.)
- Managing partitions: parted, dosfstools
- Network connectivity tools: wpasupplicant, wireless-tools, ssh
Network configuration: If your device has a wired network card, it will be enabled with DHCP. Wireless cards are not preconfigured at this point. We will probably add a way to configure them from the files in the boot partition in the future.

Configurable pre-kernel-load settings

The Raspberry firmware is set to read and apply settings from the config.txt and cmdline.txt files in the firmware partition. This will be the first partition in your image (please refer to how to find your SD card’s device if you are doing this from your regular computer), and it is mounted under /boot/firmware when booting from the Raspberry.

We do not aim to document all said settings, please refer to the Raspberry Pi documentation:

config.txt approximately maps to what you would expect on a PC’s BIOS/UEFI, settings that are applied before Linux is booted. Do note that this file is autogenerated when a new kernel or firmware package is installed, or when triggered i.e. via dpkg-reconfigure raspi-firmware.

Please refer to /etc/default/raspi-firmware for most common settings for this file, or create a /etc/default/raspi-firmware-custom with any extra parameters you wish to set.
cmdline.txt sets the Linux boot parameters.

Configurable system settings

The image is configured to process the /boot/firmware/sysconf.txt file at boot time; this functionality can be disabled by issuing:

systemctl disable rpi-set-sysconf

The currently defined settings are:

root_pw: Set a password for the root user (by default, it allows for a passwordless login)
root_authorized_key: Set an authorized key for a root ssh login. This will allow you to log in remotely.
hostname: Set the system hostname. The default hostname is rpi{model}-{builddate}

In the future, a way to configure wireless networking should be added to this section.