Windows App SDK 1.7 introduced experimental support for building ARM64EC apps, subject to several constraints.
- For managed apps, ARM64EC optimization is limited to the Windows App Runtime native binaries, as .NET does not yet support ARM64EC.
- Direct support is currently limited to Self-Contained Unpackaged apps. These two limitations are both related and due to the fact that the Windows Store does not yet support ARM64EC as a first-class architecture. So the app must not be packaged, as the app appxmanifest.xml has no ARM64EC support; and it must be self-contained, as the Windows App Runtime framework package has no ARM64EC support.
- However, it is possible to create a Packaged ARM64EC app using two techniques:
- Publishing ARM64EC application binaries in an ARM64 package. This approach requires careful observance of package dependencies in the appxmanifest.xml, to ensure that these are compatible with ARM64EC. For example, the VCLibs framework package contains ARM64X binaries, so can be consumed from an ARM64EC app in an ARM64 package.
- Dynamically loading the appropriate Windows App Runtime. This strategy, while not directly supported by the Windows App SDK, is demonstrated in the C++ Packaged sample. This sample contains two projects that build self-contained Windows App Runtime payloads, one for x64 and one for ARM64EC. The app then detects the target architecture at runtime and loads the appropriate payload.