What's the status of x64 emulation effort?

[riverar]

After reading the following issues, it's unclear what the status of this effort is. If it's complete, it's not clear how to use it (other than rearranging dotnet paths). cc: @richlander

• RFC: dotnet [Arm64 | x64] coexistence #16896
• Supporting .NET with x64 emulation on Arm64 #17463
• x64 emulation model #17464
• Add plan for x64 emulation designs#217

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[marcpopMSFT]

X64 runtimes and SDKs are now installed under sub-paths of the normal dotnet folder. They are not automatically added to the path so to use that SDK, you have to add that to the path. To use those runtimes, I believe you have to set DOTNET_ROOT_X64. @richlander would know if there are any docs outlining process besides his existing design docs: https://github.com/dotnet/designs/blob/main/accepted/2021/x64-emulation-on-arm64/x64-emulation.md

[riverar]

3 years later, it's still a bit fuzzy. Bump.

[richlander]

The model:

• x64 emulation is provided by the OS.
• Arm64 installers install Arm64 and x64 runtimes.
• The installation path for the Arm64 runtime/hive is added to the path. The native architecture is always the default, on all systems.
• The apphost is architecture-specific and will look for / use a .NET installation of the matching architecture. It does not rely on the path.
• dotnet commands, like dotnet build, inherently rely on the path (unless full path quantified). Normal path rules are used to find dotnet. The Arm64 dotnet will be used by default, as described. The path must be updated if the user wants to use the x64 installation with the help of the path. There are other options, but they all boil down to the x64 location being fully-specified.

Does that help?