macOS Catalina is said to have dropped support for 32-bit apps. But how much of the support is actually dropped? Is it only that 32-bit libraries are no longer supplied? Or will 32-bit binaries, even if statically linked, fail to launch?

If 32-bit binaries can't launch, is there any supported way for a 64-bit app to request the kernel to create a 32-bit code segment?


Unfortunately the answer is just flat no. As stated here and here Apple started requiring AppStore apps to be 64 bit in 2018. They have been working on this for a while and with Catalina they are finally shutting the door entirely.

Edit: This sheds more light on app development.

  • You're talking about the organizational side of things which is what all the news are about, but the question is purely technical. – Grishka Jul 30 at 20:42
  • @Grishka What are you talking about? There is only one side of this question, the technical side. Apps either work or they don't. What organizational side is there? – Thomas Nelson Jul 31 at 0:53
  • 32-bit apps don't work as is on an unmodified OS. There's a lot of components to 32-bit support on a 64-bit OS. The question is how much of those are removed, if any, and whether it is feasible/possible at all to restore this support by modifying the system. – Grishka Jul 31 at 10:19
  • This answer is wrong and unhelpful. OP essentially asks 1) Does XNU still recognize 32-bit mach-O? 2) Does XNU still recognize fat binaries? 3) Does dyld still recognize 32-bit mach-O? 4) Does dyld still recognize fat binaries? 5) Is a fat libSystem still shipped in Catalina? 6) How many other fat binaries does Catalina still ship? None of these were answered. – alexchandel Sep 11 at 15:19

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