PureDarwin intends to make Apple’s Darwin usable with a MATE desktop, future custom desktop environment, and more

Remember Darwin? It’s the core of Apple’s macOS, and the company has always – sometimes intermittently – released its source code as open source. Not much ever really happens with Darwin, and any attempts at building a usable operating system on top of Darwin have failed. There was OpenDarwin, which at one point could run a GNOME desktop, but in 2006 it shut itself down, stating:

Over the past few years, OpenDarwin has become a mere hosting facility for Mac OS X related projects. The original notions of developing the Mac OS X and Darwin sources has not panned out. Availability of sources, interaction with Apple representatives, difficulty building and tracking sources, and a lack of interest from the community have all contributed to this. Administering a system to host other people’s projects is not what the remaining OpenDarwin contributors had signed up for and have been doing this thankless task far longer than they expected. It is time for OpenDarwin to go dark.
↫ OpenDarwin announcement from 2006 (archived)

Any other attempts at making Darwin work as a standalone operating system were further frustrated by the fact that Apple stopped releasing bootable Darwin images, so Darwin never amounted to much more than Apple throwing some code over the fence every now and then for some cheap goodwill among the few people who still believe Apple cares about open source. However, the dream is still alive – the idea that you could use Darwin to build a general purpose operating system, perhaps one with some semblance of compatibility with macOS software, is an attractive one.

Enter PureDarwin. This project has been around for a while now, releasing an X11-capable build of Darwin somewhere in 2015, followed long, long after that by a CLI-only build in 2020. A few days ago, the project announced an ambitious change in direction, with a plan and roadmap for turning PureDarwin into a general purpose operating system.

The PureDarwin project, originally created to bring Apple’s open-source Darwin OS to more people, is heading in a fresh new direction with some clear short-term and long-term goals. These new plans are all about breathing new life into PureDarwin. In the short term, we’re focused on getting some solid basics in place with graphical interfaces using MATE Desktop and LightDM, so users can get a functional and accessible experience sooner rather than later. Looking further down the line, the long-term goals—shown in some early wireframes—are about creating a fully featured, polished desktop experience that’s easy to use and visually appealing. Plus, a new versioning system will make it clear how PureDarwin is progressing independently from Apple’s Darwin updates, making it easier for everyone to keep track. This refreshed direction sets PureDarwin up to grow from its roots into a user-centered operating system.
↫ PureDarwin announcement

These plans and roadmap sound quite well thought-out to me. I especially like that they first focus on getting a solid MATE desktop running before shifting to building a more custom desktop environment, as this makes it much easier – relatively speaking – to get people up and running with Darwin. Once Darwin with MATE is halfway usable, it can serve its job as a development platform for the more custom desktop environment they have planned. It won’t surprise you, by the way, that the sketches for the custom desktop environment are very Apple-y.

As part of the goals of creating a usable MATE desktop and then a more custom desktop environment, a whole bunch of low-level things need to be handled. All the kexts (drivers) required for Darwin to boot need to be built, and CoreFoundation needs to be updated, a process that was already under way. On top of that, the project wants to focus on getting Wayland to work, make Darwin buildable under BSD/Linux, and develop an installer.

Beyond those goals, the project has an even bigger, tentative ambition: API compatibility with macOS. They make it very clear they’re not at all focused on this right now, and consider it more of a pie-in-the-sky goal for the the distant future. It’s an interesting ambition we’ve seen tried various times before, and it surely won’t be even remotely easy to get it to a level where it could do much more than run some command-line utilities. Darling, a similar project to run macOS binaries on Linux in the style of Wine, has only recently been able to run some small, very basic GUI applications.

I like all of these goals, and especially getting it to a state where you can download a Darwin ISO running MATE should be entirely realistic to achieve in a short timeframe. A custom desktop environment is a lot more work of course, all depending on how much they intend to reuse from the Linux graphics and desktop stack. Anything beyond that, and it becomes much murkier, obviously. As always, it’s all going to come down to just how many active and enthusiastic contributors they can attract, and more importantly retain once the initial excitement of this announcement wears off.