The latest iteration of the official Raspberry Pi OS, based on Debian 11 ‘Bullseye’, adds a lot of new features and improvements. However, some Raspberry Pi users have asked for an option to roll back certain parts of the operating system to restore some functionality required for certain projects.

Therefore the Raspberry Pi Foundation has made a ‘Legacy’ version of the OS available. Let’s take a look at it and why you might need it.

What’s Changed in Bullseye?

As a major update, the Bullseye version of Raspberry Pi OS features quite a few changes. Most notably, all of the desktop components and applications now use version 3 of the GTK+ user interface toolkit instead of version 2.

On Raspberry Pi models with 2GB or more RAM, a new Mutter window manager is used instead of the previous Openbox, resulting in a more modern and appealing desktop user interface. There’s also a switch to the KMS video driver for controlling the connection to a display.

For users of Raspberry Pi Camera Modules, Bullseye has dropped support for the old raspistill and raspivid tools for shooting stills and video in favor of libcamera.

A Bullseye bonus is that it can even make your Raspberry Pi 4 run faster.

What’s the Problem?

As noted by Raspberry Pi Chief Product Officer Gordon Hollingworth in the official blog post, moving to a new upstream branch of the OS can cause significant problems for some users.

“With the new branches come new versions of libraries and new interfaces. Old software and interfaces become unsupported, and the way to do specific things changes,” says Hollingworth.

This can cause problems for some users, including those in education and running industrial applications using Raspberry Pi, who value an unchanging OS or have developed software to use particular library versions.

What Is Raspberry Pi OS (Legacy)?

The alternative Legacy version of Raspberry Pi OS rolls back certain changes to restore functionality that some users have been relying on.

Based on the previous release, Raspberry Pi OS Buster, Legacy replaces Bullseye’s hardware-accelerated version of Chromium with the upstream software browser.

The Linux kernel is branched at 5.10.y and only takes security patches from the Linux kernel. Raspberry Pi firmware is branched and only takes security and hardware support patches for existing products.

Camera Control

The new libcamera driver for Camera Modules featured in Raspberry Pi OS Bullseye no longer works with the Picamera Python bindings. While a new version of the latter, Picamera2, is being developed, there is currently no way to operate the camera easily from Python programs.

Raspberry Pi OS (Legacy) features the earlier raspistill and raspivid commands for shooting stills and video, which will work with the Picamera library in Python.

Bullseye users can also still restore access to raspistill and raspivid. First, make sure the OS is up to date, then open a Terminal window and type sudo raspi-config. Go to Interface Options, then select Legacy Camera and reboot.

How Do I Get Legacy?

Raspberry Pi OS (Legacy) is downloadable from the official Raspberry Pi software page, in Desktop and Lite versions. It is also available in the Raspberry Pi OS (other) menu of the Raspberry Pi Imager tool for flashing a microSD card. Legacy will run on any Raspberry Pi model, including the new Zero 2 W.

For Debian Buster, support will be available until June 2024. For the Linux 5.10 kernel, it will be until December 2026. Note that if Debian Bookworm becomes stable within this period, however, Raspberry Pi OS (Legacy) will switch to Bullseye.

Roll Back to Legacy

While the latest Bullseye version of Raspberry Pi OS offers a bunch of new features, extra functionality, greater open-source and Linux standardization, and improved user-friendliness, it may not be suitable for all users.

Therefore, the ‘new’ Legacy version enables offers a way to stick with an alternative Buster-based branch of Raspberry Pi OS going forward and, according to the Raspberry Pi blog post, it will “remain supported while the various components continue to receive updates.”