3 ms·

I’m curious why we have aarch64 and not ARM64?

simias 6y ago
Aren't they one and the same thing? Like x86-64 and amd64?
grugagag 6y ago
My understanding is that it is the same thing https://en.m.wikipedia.org/wiki/AArch64 https://en.m.wikipedia.org/wiki/AArch64
xxpor 6y ago
"AArch64 is the 64-bit state introduced in the Armv8-A architecture (https://en.wikipedia.org/wiki/ARM_architecture#ARMv8-A https://en.wikipedia.org/wiki/ARM_architecture#ARMv8-A). The 32-bit state which is backwards compatible with Armv7-A and previous 32-bit Arm architectures is referred to as AArch32. Therefore the GNU triplet for the 64-bit ISA is aarch64. The Linux kernel community chose to call their port of the kernel to this architecture arm64 rather than aarch64, so that's where some of the arm64 usage comes from. As far as I know the Apple backend for aarch64 was called arm64 whereas the LLVM community-developed backend was called aarch64 (as it is the canonical name for the 64-bit ISA) and later the two were merged and the backend now is called aarch64." https://stackoverflow.com/questions/31851611/differences-between-arm64-and-aarch64 https://stackoverflow.com/questions/31851611/differences-bet...
masklinn 6y ago
Because ARM decided to "relabel" their 32-bit architecture as AArch32 and the 64b one as AArch64, and most people just followed with that to avoid confusion. Furthermore "ARM64" collides a slight bit with ISA revisions naming scheme, which is of the form ARMvX-<variant>.
ben-schaaf 6y ago
After a little research it looks like aarch64 (Arm ARCHitecture 64-bit) is the official name. ARM64 comes from the previously closed source llvm backend for aarch64 made by Apple: https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk, but is now used as shorthand, like x64.
- cellularmitosis 6y ago
  > like x64 I seem to recall reading somewhere that "x64" actually referred to something which was distinct from x86_64 (was it a special mode of using 32-bit pointers with a 64-bit kernel? I can't remember exactly now), but now that I am googling for it, I can't seem to find anything.
  - vlovich123 6y ago
    You're thinking of x32 ABI [1]. [1] https://en.wikipedia.org/wiki/X32_ABI https://en.wikipedia.org/wiki/X32_ABI

Aren't they one and the same thing? Like x86-64 and amd64?

My understanding is that it is the same thing https://en.m.wikipedia.org/wiki/AArch64 https://en.m.wikipedia.org/wiki/AArch64

xxpor 6y ago

"AArch64 is the 64-bit state introduced in the Armv8-A architecture (https://en.wikipedia.org/wiki/ARM_architecture#ARMv8-A https://en.wikipedia.org/wiki/ARM_architecture#ARMv8-A). The 32-bit state which is backwards compatible with Armv7-A and previous 32-bit Arm architectures is referred to as AArch32. Therefore the GNU triplet for the 64-bit ISA is aarch64. The Linux kernel community chose to call their port of the kernel to this architecture arm64 rather than aarch64, so that's where some of the arm64 usage comes from. As far as I know the Apple backend for aarch64 was called arm64 whereas the LLVM community-developed backend was called aarch64 (as it is the canonical name for the 64-bit ISA) and later the two were merged and the backend now is called aarch64." https://stackoverflow.com/questions/31851611/differences-between-arm64-and-aarch64 https://stackoverflow.com/questions/31851611/differences-bet...

masklinn 6y ago

Because ARM decided to "relabel" their 32-bit architecture as AArch32 and the 64b one as AArch64, and most people just followed with that to avoid confusion. Furthermore "ARM64" collides a slight bit with ISA revisions naming scheme, which is of the form ARMvX-<variant>.

ben-schaaf 6y ago

After a little research it looks like aarch64 (Arm ARCHitecture 64-bit) is the official name. ARM64 comes from the previously closed source llvm backend for aarch64 made by Apple: https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk, but is now used as shorthand, like x64.

cellularmitosis 6y ago
> like x64 I seem to recall reading somewhere that "x64" actually referred to something which was distinct from x86_64 (was it a special mode of using 32-bit pointers with a 64-bit kernel? I can't remember exactly now), but now that I am googling for it, I can't seem to find anything.
- vlovich123 6y ago
  You're thinking of x32 ABI [1]. [1] https://en.wikipedia.org/wiki/X32_ABI https://en.wikipedia.org/wiki/X32_ABI