[simonh]

> Apple Silicon has a (mostly) hardware translation layer…

I can’t imagine what you mean by this, Rosetta 2 is a binary translation system implemented in software, based on QuickTransit. There are a few features implemented in Apple Silicon to make translation easier and more efficient, such as supporting Intel memory ordering, but thats about it.

I think it’s reasonable to worry about how long rosetta2 will be available. The first version, that allowed Intel Macs to run PowerPC binaries, was available for 5 years. Having said that, there’s no guarantee versions of MacOS beyond 5 years time will run on today’s M1 anyway (though M1 compatible versions will likely still get updates beyond then).

[Wowfunhappy]

I can't say what Apple will do, but I'm really hoping they'll keep Rosetta 2 around for longer than Rosetta 1.

For starters, the Mac became a lot more popular in the Intel era than it ever was while on PPC, so there's a much larger quantity of legacy software that Apple would be cutting off. Secondly, the overall user experience of running apps via Rosetta 2 seems to be a lot better than Rosetta 1. And for Apple, Rosetta 2 was developed in-house and doesn't require continuous licensing fees to keep around (not that I'm particularly sympathetic to Apple's pocketbook.)

[alwillis]

And for Apple, Rosetta 2 was developed in-house and doesn't require continuous licensing fees to keep around (not that I'm particularly sympathetic to Apple's pocketbook.)

I don't think any of those things matter; Apple will stop supporting Rosetta 2 as quickly as they can. They announced the transition to Apple Silicon will be two years and unless something unforeseen happens, that's what it's going to be.

I suspect that Rosetta 2 won't be available for new Apple Silicon Macs running macOS five years from now.

Of course, no matter how many years in advance Apple warns that a particular technology is going to be deprecated, that never stops people from complaining vociferously when it happens.

A great example is 32-bit apps, where Apple gave something like an 8-year heads-up that 32-bit apps were going away, which happened a few years ago but it's not hard to find threads on HN where people are still complaining about it.

[Wowfunhappy]

> A great example is 32-bit apps, where Apple gave something like an 8-year heads-up that 32-bit apps were going away, which happened a few years ago but it's not hard to find threads on HN where people are still complaining about it.

But actually, I personally believe that the actual reason Apple killed 32bit support was because they didn't want to build it into Rosetta. (And they didn't want Intel computers to be able to run anything their new Apple Silicon computers could not.)

Before Apple Silicon was on the horizon, it was no problem for Apple to keep 32 bit and carbon libraries around for eight years because they might as well, it's not doing any harm.

(I'm also one of the people who was/is mad about 32 bit support, but I acknowledge that my opinion on the matter has no bearing on what Apple will decide to do.)

[alwillis]

But actually, I personally believe that the actual reason Apple killed 32bit support was because they didn't want to build it into Rosetta. (And they didn't want Intel computers to be able to run anything their new Apple Silicon computers could not.)

I doubt it; that’s not how Apple rolls. They’re not like Microsoft which keeps legacy technologies around for backwards compatibility for several years after a technology is no longer mainstream.

Reasonable people can disagree but Apple is about the present and the future, not the past. Sure, they could have kept Carbon around or pick your favorite framework from the past but that’s generally not their thing.

Occasionally something from their past reappears, like the QuickDraw GX font format from the 90s that became the basis for today’s variable fonts on the web.

Apple has always been fine with some software not making the leap to the next operating system or processor architecture.

We’ve seen this going back to 68K to PowerPC then to Intel and now ARM.

Being able to run x86 operating systems (Windows) natively on Intel Macs was a huge selling point not that long ago and now it’s an afterthought that current buyers (mostly) don’t care about. Microsoft would bring Windows for ARM to Apple Silicon and so far, they haven’t.

And while this is all going on, Macs have never been more popular.

[astrange]

x86-32 was removed because it’s significantly less secure and performant than x86-64 and there were unfixable issues with the ABI like fragile ObjC superclasses. Don’t need any secret projects to explain that. The only people who seem to still have a problem are video game developers, who should maybe try writing clean code.

32-bit isn’t completely gone, it’s still on watchOS.

[Isthatablackgsd]

I would say it is more of the legacy codes that Apple don't want to keep providing support for backward compatibility. And it uses up spaces in your drive if they need to keep 32-bit library in case for those app that are running in that level.

Microsoft want to do that but it will be a huge risk since it will alienate their enterprise consumers.

[saagarjha]

> But actually, I personally believe that the actual reason Apple killed 32bit support was because they didn't want to build it into Rosetta.

Rosetta 2 contains functionality to correctly emulate 32-bit Intel code.

[Wowfunhappy]

It's not the 32 bit code though, it's all the old libraries (carbon) which happen to also be 32 bit.

[saagarjha]

Right. The 32 bit emulation is only really useful to CrossOver.

[my123]

For Rosetta (1), QuickTransit was bought up by IBM. Rosetta disappeared not very long after that.

[olliej]

Rosetta 2 has nothing to do with Rosetta 1 (other than the name), nor any other company’s software.

[tardyp]

Looks like QuickTransit was a jit engine which was the base of Rosetta 1. Rosetta 2 is AOT translation.

[simonh]

They’re both based on QuickTransit, but Rosetta 2 has an AOT mode as well as JIT. I’m sure the R2 engine is more advanced than the original engine, Apple employed several engineers from the original team, but it still uses and is based on licensed tech.

[GeekyBear]

My understanding is that Rosetta 2 is based on LLVM.

Even the company that made QuickTransit is gone now, having been bought out by IBM a decade ago.

[monocasa]

My understanding is that Apple hired a lot of the staff of Transitive, and had a more or less do whatever you want license with source access. Ad that the AOT mode is based on LLVM, but the JIT piece is still pretty core to the design (hence why other JITs run well on top of it).

[my123]

It’s not based on LLVM, that’s way too heavy for the use case.

The same backend is used for AoT and JIT compilation. It uses a custom lightweight IR that’s really close to x86 itself, with a big focus towards reducing translation times.

Rosetta 2/Cambria was fully written in-house.