Linked by Thom Holwerda on Sat 3rd Feb 2018 14:15 UTC, submitted by Drumhellar
Mac OS X

When users attempt to launch a 32-bit app in 10.13.4, it will still launch, but it will do so with a warning message notifying the user that the app will eventually not be compatible with the operating system unless it is updated. This follows the same approach that Apple took with iOS, which completed its sunset of 32-bit app support with iOS 11 last fall.

This is good. I would prefer other companies, too, take a more aggressive approach towards deprecating outdated technology in consumer technology.

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RE: Comment by Kroc
by teco.sb on Sat 3rd Feb 2018 15:47 UTC in reply to "Comment by Kroc"
teco.sb
Member since:
2014-05-08

As someone who has done both x86 and x86-64 assembly programming, I can tell you that is not the case. Even in long-mode, the AMD64 additions still seems to favor 32-bits operations over 64-bits ones.

Instructions are shorter (a function of x86's variable instruction size) when you work on 32-bit registers and instructions referencing the extended registers (r8-r15) require an extra byte, making them awkward. As an example, in long-mode adding 2 32-bit registers is only a 2-byte instruction, but requires 3-bytes for the same operation on 64-bit registers. That's a 50% increase in code size for something you may or may not need.

I think the problem with supporting 32 and 64-bit applications is in the syscall mechanism. If you take a look at Linux's syscall numbers, you will notice they are completely different for each architectures. This is true for every kernel (as far as I know). So in order for the kernel to be able to run a 32-bit compiled program in a 64-bit kernel, it first needs to identify that the application is going to be making 32-bit syscalls, and then translate those calls to the equivalent 64-bit syscall every time.

I will also add that the syscall convention for x86 and x86-64 are completely different. So it really is a translation for every kernel call.

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