Dual-booting Canonical‘s Ubuntu Linux and Android on tablets and smartphones has moved a small step closer to reality with the release of a new version of the Ubuntu Dual Boot Installer. Codenamed M9, the release offers support for Ubuntu OS upgrades, along with a slew of other enhancements.

Alas, Canonical is keen to emphasize that the Ubuntu Dual Boot Installer is for developers only, and always will be. The company is not building it with the goal of encouraging us plain folk to use it to install Ubuntu on our Android mobile devices.

Still, the tool is an important proving ground for preparing Ubuntu to run well on mobile hardware, which is a central pillar of Canonical’s grand vision of “converging” Ubuntu across different types of devices. For that reason, the M9 release of the software is significant as proof of Canonical’s progress toward making dual-boot Ubuntu and Android devices a reality.

The biggest-ticket change in the release, as developer David Planella explained recently, is support for upgrading the version of Ubuntu that is installed on a dual-boot device from within the Ubuntu installation, using the standard upgrade process. Previously, upgrades to the Ubuntu version were possible only from the “Android” side of the dual-boot environment, but this change better positions Ubuntu to stand on its own.

In addition, “sideload” support in the M9 release allows users to install Ubuntu on mobile devices using images that they downloaded previously, rather than requiring them to download the images at the time of installation. The same feature makes it possible to install custom Ubuntu images.

And that’s not all. Planella outlined other updates, including bug fixes and additional features that make Ubuntu installations easier, in his post.

If you’re eager to install Ubuntu alongside Android on your tablet or smartphone, the M9 release may be little cause for elation, since production-quality functionality is clearly a ways away. The Dual Boot Installer still supports only a narrow range of specific hardware devices, and if very basic features such as support for upgrading Ubuntu from within Ubuntu are still a big deal at this point in the development process, the day when an Ubuntu installer for mobile hardware offers a full-fledged user experience is not on the horizon yet. But Canonical remains committed to making that day a reality, and Ubuntu developers are progressing toward it.