Taking Control of Windows Feature Control With Mach2

Posted on April 15, 2018 by Rafael Rivera in Windows 10 with 8 Comments

Many months ago, I wrote a tool – Mach2 – to help me wrangle hidden features present in pre-release builds of Windows 10. Today, I’m making the tool’s sources available on GitHub.

Feature Control is a system used to gate off new and unfinished features from production users in production code. The latter bit is important; it helps teams – like the Notepad team – safely work on changes in a constantly evolving master codebase, reducing costly integration efforts and boosting transparency. Teams needing to work with this pre-production code can easily flip a switch on their Windows machines – like Feature_FluentNotepadWorkForMaryJo. Everyone else, however, would continue to use production code and be none the wiser.

This is where Mach2 comes in.

Mach2 manages the Feature Store, a core component of Feature Control, where these switches live. It can display which features are enabled or disabled on a machine. It can also assist with the discovery of interesting features to flip on and off.

Remember our Shoulder Tap Internals post? That was unfinished code discovered using this tool, feature 9146043. Similarly, Quick Pair is tied to 12507179. (For those wondering, the IDs typically correspond to the feature’s implementation task in Microsoft’s internal source control system hosted on the Visual Studio Online platform.)

But there’s a catch: Turning on unfinished features can completely trash your Windows installation. This isn’t Fast Ring code – this is the raw developer-only stuff. You do not want to use this on machines you don’t feel comfortable wiping at a moment’s notice.

If you’re still interested in Mach2, or even want to help out, jump over to the GitHub repository.

Happy hacking.

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