Is Ubuntu Eyeing Immutability? Canonical Restarts Core Desktop and Eyes a Firmware Change for LTS

Canonical has restarted development of Ubuntu Core Desktop, an immutable, snap-based take on Ubuntu that sat dormant after a developer preview in 2023. Jon Seager, Canonical’s VP Engineering for Ubuntu, says a dedicated team is now working on it.

The objective is for it to grow into the default Ubuntu desktop experience as the project matures. What you know of Ubuntu Desktop is not changing, and Jon says that the various Ubuntu flavors are under no pressure to build Core versions of their own.

Separately, Juerg Haefliger, a Canonical engineer, has proposed a firmware package for Ubuntu LTS releases that would shield older kernels from firmware written for newer ones.

Both are early in development and things could still change.

What’s Ubuntu Core Desktop?

Ubuntu Core is Canonical’s operating system for IoT and embedded devices, and work on it started in 2014. It is immutable and strictly confined, with the kernel, OS image, and apps being kept separate and updated independently of each other.

On Core Desktop, everything is a Snap, from the bootloader and kernel to the desktop environment and your apps. That makes the system harder to break and easier to recover.

The 2023 desktop preview fell short of expectations because it packed much of the desktop, including GNOME and its login screen, into one bulky Snap package. The new approach is to get those pieces separated.

A newly-assigned team of developers has already made good progress moving the old preview onto the newer Core 26 base. Infrastructure for daily image builds is expected to be ready within the coming weeks, and the work is set to run through the 27.04 cycle.

Apps are a big hurdle since Core Desktop only runs strictly confined Snaps, and classic ones like VS Code can’t run on it directly. Jon’s preferred idea is to host them in a Workshop, Canonical’s sandboxed development environment, and show their windows on the main desktop.

Permissions prompting is another piece he considers key to Core’s success. Under this, the system would ask users before a confined app touches things like the camera, microphone, or home directory.

What’s the firmware proposal about?

Ubuntu LTS releases launch with one kernel, known as GA, and the hardware enablement (HWE) stack later rolls out newer kernels for that same release. Ubuntu 24.04 launched on kernel 6.8, and its current HWE kernel is 7.0.

Desktop installs of 24.04 follow HWE by default, while servers stay on GA unless you opt in. Both kernels share one firmware package today, so firmware backported for the newer kernel also lands on GA systems, and Juerg notes that vendors rarely test an old kernel with new firmware.

He points to a couple of AMD regressions on GA systems after recent 24.04 backports. His solution to the problem is a linux-firmware-hwe package that HWE kernels would depend on.

It would carry the complete firmware set from the Ubuntu release the HWE kernel comes from, in place of a handful of hand-picked files backported to the LTS.

GA systems would stay on the regular firmware, and the two sets can’t be installed together. A machine with both kernels would load the HWE firmware even when booting GA, and the bug report for this change has left the workaround as something that might be considered.

As for when this might land, the report is still quite new, with no assignee mentioned and a test case section that only says TBD. Though it is being tracked against Ubuntu 27.04, which is set for an April release next year, codenamed “Tenacious T-Rex.”

Neither change affects a regular Ubuntu user yet, and once the daily Core Desktop images start showing up, we shall see how far the project can go in its quest for immutability.