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Many server-class Aarch64 chips have dropped support for 32 bit so in those cases it's not even an option.

• adrian_b 2y ago
  Also some of the latest smartphone chips have a part of the cores that no longer can execute 32-bit code. The next generations will not include any core supporting the 32-bit ISA.
• ithkuil 2y ago
  You can still use 32-bit wide addresses in 64-bit mode and sign-extend them into 64-bit registers. If you have a statically compiled binary all you need is compiler support for 32-bit address mode in the otherwise 64-bit ready instruction set and on x86 you get access to more registers etc but you don't pay the price for the wider addresses stored in data structures. OTOH if you use shared libraries you also have to have your shared libraries compiled in that mode too. The difficulty of dealing with that depends also if you gave a hybrid system or a full 32 bit userspace
  • leni536 2y ago
    Yes, that's an alternate ABI with 32-bit addressing targeting the same 64-bit instruction set. But it's not trivial, as you described. You might also want some kernel support too, and there might not be enough demand to maintain that support.
  • namibj 2y ago
    AKA x32 on AMD64.