27.12 Universal binaries on macOS

The supplied LispWorks (64-bit) for Macintosh images are universal binaries, which run the correct native architecture on arm64 (Apple silicon) and x86_64 (Intel) Macintosh computers by default.

A running Lisp image only supports one architecture, chosen when the image was started. On a x86_64 based Macintosh, this is always the x86_64 architecture. On an arm64 Macintosh, a running LispWorks image can be either the native arm64 architecture or the x86_64 architecture (using Rosetta 2).

Functions such as save-image and deliver mentioned in 27.11 Creating a new executable with code preloaded create an image containing only the running architecture and functions that operate on fasl files such as compile-file and load only support the running architecture.

To create a universal binary, you can use one of these methods:

• Build a universal binary in the Application Builder in the LispWorks IDE.
• Use save-universal-from-script.
• Create the x86_64 and arm64 images separately, and then combine them use create-universal-binary.

Normally the Application Builder and save-universal-from-script are much more convenient, and create-universal-binary should be used only very special cases.