I MUST write to a unvirtualized HKLM key in my packaged app

[catmanjan]

Describe the bug

My app needs to write to some HKLM keys for Office interop support, however I can't find a solution.

I've looked at the Registry.dat but changes made using it are not visible to Office, I've looked at Package Support Framework, but it doesn't support ARM64 (which is required for Copilot+ PCs)

Is there a solution for me, or do I need to abandon packaging?

Something I don't quite understand, is that my app is packaged and therefore shouldn't be able to write to HKLM, yet when I call StorageProviderSyncRootManager.Register() keys are written to HKLM which are later read by explorer.exe - so how is that occuring?

Steps to reproduce the bug

Try to write to HKLM

Expected behavior

No response

Screenshots

No response

NuGet package version

Latest

Packaging type

Packaged (MSIX)

Windows version

No response

IDE

No response

Additional context

No response

[wjk]

It is entirely possible to exclude certain Registry keys from virtualization. Here is an example of how. Note that you’ll need to put <rescap:Capability Name="unvirtualizedResources" /> in your package capabilities to do this.

[DrusTheAxe]

HKLM doesn't get virtualized writes. And your virtualized HKLM registry data provided with your virtual (VREG) is only visible to you, which does no good when you need to share with others.

It is entirely possible to exclude certain Registry keys from virtualization. Here is an example of how. Note that you’ll need to put <rescap:Capability Name="unvirtualizedResources" /> in your package capabilities to do this.

If you meant HKCU then yes, writes to HKCU are virtualized and not visible to others. As @wjk notes you can punch holes through your I/O Virtualization bubble to write to the real HKCU for visibility with others. See Flexible Virtualization more details.

Keep in mind, whatever you write to HKCU w/o I/O Virtualization will remain until you (or someone else) deletes it. MSIX Deployment WON'T do this for you, as you're scribbling on the system outside MSIX's awareness. Leaving behind such data when you're uninstalled is informally referred to as 'winrot' and (as you might guess) is frowned upon and discouraged, for the obvious reasons.

[catmanjan]

I recently discovers that my app can write to some of the HKLM keys at runtime with no issues, even without admin privileges, and those keys can be read by others

The only requirement seems to be that the user has write access to the key

I don’t understand how because the documentation implies that it shouldn’t work in the new apppackage framework

[DrusTheAxe]

I don’t understand how because the documentation implies that it shouldn’t work in the new apppackage framework

What documentation?

Got link?

[catmanjan]

https://learn.microsoft.com/en-us/windows/msix/desktop/desktop-to-uwp-behind-the-scenes#common-registry-operations