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> Does any of this matter still or should we embrace this 64 bit only world? Will CPU makers remove i686 support? I guess we're going to find out. We're alread

> Does any of this matter still or should we embrace this 64 bit only world? Will CPU makers remove i686 support? I guess we're going to find out. We're already on this path, Intel has proposed an "X86-S" subset which drops support for booting into 16/32-bit modes (though 32-bit applications would still be supported under a 64-bit OS), ARM Cortex-A cores already dropped support for 32-bit boot a few years ago and the latest ones are also dropping support for 32-bit applications, so the whole stack has to be 64-bit. Apple preemptively killed 32-bit apps even on hardware that could technically still support them, and their current hardware doesn't support 32-bit at all, not even in Rosetta.

my123 3y ago
Rosetta supports 32-bit code execution via a very basic (segment-level) facility, designed for use by Wine.
- jsheard 3y ago
  TIL. I'm surprised they went out of their way to accomodate emulating 32-bit Windows apps, when they cut off 32-bit Mac apps completely.
  - plorkyeran 3y ago
    Dropping 32-bit macOS apps let them drop the second copy of every system library, and possibly even more importantly, support for the old obj-c runtime that was weird and different from the runtime used on every other platform. Supporting 32-bit wine is a much smaller burden.
    - MBCook 3y ago
      Which is especially useful on phones that are much more memory constrained than desktops.
zahllos 3y ago
For the modern server/desktop and even laptop, that's also no bad thing. It is somewhat ridiculous that UEFI bioses, internally, still boot in 16-bit real mode and have to do all the steps your bios bootloader used to do to set up a 64-bit environment ready to go: https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a..., https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a..., https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a... Why not just start the CPU in "long mode", which is what everyone is using it for, in the first place? These newer ARM processors support 32-bit code at EL0 only (userspace). That seems like a reasonable approach for x86 as well and the freebsd announcement has this to say: > There is currently no plan to remove support for 32-bit binaries on 64-bit kernels. So for the moment, you can run 32-bit applications just fine.
- jsheard 3y ago
  > These newer ARM processors support 32-bit code at EL0 only (userspace). Even that is being phased out, starting from 2021 ARMs reference cores mostly dropped 32-bit support, with the Cortex-X2 big cores and Cortex-A510 small cores being 64-bit only, and only the medium Cortex-A710 cores retaining the ability to run 32-bit code in userspace. With the next generation the medium cores lost 32-bit support, but the small cores gained 32-bit support again, so the chips can barely still run 32-bit code but it's relegated to only running on the least performant cores. I'm sure they'll drop it altogether as soon as they think the market will accept it.
  - ksec 3y ago
    I think we need to be more specific, since on x86 64bit instructions are a superset of 32bit. On ARM they are different with AArch32 and AArch64 being two separate set of instructions. It is AArch32 that is being dropped and no longer required.
judge2020 3y ago
> Apple preemptively killed 32-bit apps even on hardware that could technically still support them, and their current hardware doesn't support 32-bit at all, not even in Rosetta. Slightly related: visionOS references "iOS" for old 32-bit apps when you view them on the App Store. https://rr.judge.sh/Acaciarat%2FIMG_0002.PNG https://rr.judge.sh/Acaciarat%2FIMG_0002.PNG

my123 3y ago

Rosetta supports 32-bit code execution via a very basic (segment-level) facility, designed for use by Wine.

jsheard 3y ago
TIL. I'm surprised they went out of their way to accomodate emulating 32-bit Windows apps, when they cut off 32-bit Mac apps completely.
- plorkyeran 3y ago
  Dropping 32-bit macOS apps let them drop the second copy of every system library, and possibly even more importantly, support for the old obj-c runtime that was weird and different from the runtime used on every other platform. Supporting 32-bit wine is a much smaller burden.
  - MBCook 3y ago
    Which is especially useful on phones that are much more memory constrained than desktops.

zahllos 3y ago

For the modern server/desktop and even laptop, that's also no bad thing. It is somewhat ridiculous that UEFI bioses, internally, still boot in 16-bit real mode and have to do all the steps your bios bootloader used to do to set up a 64-bit environment ready to go: https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a..., https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a..., https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a2f911d2fb8b3d2f5768/UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm https://github.com/tianocore/edk2/blob/edc6681206c1a8791981a... Why not just start the CPU in "long mode", which is what everyone is using it for, in the first place? These newer ARM processors support 32-bit code at EL0 only (userspace). That seems like a reasonable approach for x86 as well and the freebsd announcement has this to say: > There is currently no plan to remove support for 32-bit binaries on 64-bit kernels. So for the moment, you can run 32-bit applications just fine.

jsheard 3y ago
> These newer ARM processors support 32-bit code at EL0 only (userspace). Even that is being phased out, starting from 2021 ARMs reference cores mostly dropped 32-bit support, with the Cortex-X2 big cores and Cortex-A510 small cores being 64-bit only, and only the medium Cortex-A710 cores retaining the ability to run 32-bit code in userspace. With the next generation the medium cores lost 32-bit support, but the small cores gained 32-bit support again, so the chips can barely still run 32-bit code but it's relegated to only running on the least performant cores. I'm sure they'll drop it altogether as soon as they think the market will accept it.
- ksec 3y ago
  I think we need to be more specific, since on x86 64bit instructions are a superset of 32bit. On ARM they are different with AArch32 and AArch64 being two separate set of instructions. It is AArch32 that is being dropped and no longer required.

judge2020 3y ago

> Apple preemptively killed 32-bit apps even on hardware that could technically still support them, and their current hardware doesn't support 32-bit at all, not even in Rosetta. Slightly related: visionOS references "iOS" for old 32-bit apps when you view them on the App Store. https://rr.judge.sh/Acaciarat%2FIMG_0002.PNG https://rr.judge.sh/Acaciarat%2FIMG_0002.PNG