Comment by cwzwarich
1 year ago
I was the only person working on it for ~2 years, and I wrote the majority of the code in the first version that shipped. That said, I’m definitely glad that I eventually found someone else (and later a whole team) to work on it with me, and it wouldn’t have been as successful without that.
When people think of a binary translator, they usually just think of the ISA aspects, as opposed to the complicated interactions with the OS etc. that can consume just as much (or even more) engineering effort overall.
As someone frustrated in a team of 10+ that is struggling to ship even seemingly trivial things due to processes and overheads and inefficiencies, I would really appreciate some insights on how do you organize the work to allow a single developer to achieve this.
How do you communicate with the rest of the organization? What is the lifecycle and release process like? Do you write requirements and specs for others (like validation or integration) to base their work on? Basically, what does the day to day work look like?
Well, the first thing to realize about scaling codebases with developers is that an N developer team will usually produce a codebase that requires N developers to maintain. So by starting small and staying small until you reach a certain critical mass of fundamental decisions, you can avoid some of the problems that you get from having too many developers too early. You can easily also fall into the reverse trap: a historical core with pieces that fit too well together, but most of the developers on the team don’t intuitively understand the reasons behind all of the past decisions (because they weren’t there when they happened). This can lead to poorly affixed additions to a system in response to new features or requirements.
As far as Rosetta in particular was concerned, I think I was just in the right environment to consistently be in a flow state. I have had fleeting moments of depression upon the realization that I will probably never be this productive for an extended period of time ever again.
Thank you for what you did with Rosetta 2. It is outstanding.
On your last point, I’ve felt something like that myself and I hold onto hope that it isn’t true for myself (and now for you in your future endeavors). But even if it is true, you achieved something superhuman in your niche and the vast majority of people throughout the history of time have no idea what that is like. Tasting Heaven cannot last too long while on Earth. Maybe AI will bring us a little bit closer to that Heaven.
Thanks for sharing. Do you have an estimation of LoC? I know it's a BS indicator but just curious. I'd imagine it's something difficult but not too large.
>How do you communicate with the rest of the organization?
I wonder if Apple's renowned secrecy is a help with this. If nobody outside your small team knows what you are doing then it is hard for them to stick their oar in.
For the record I was interning on Cameron's team while he worked on Rosetta 2 and didn't even know myself what he worked on (the rest of the team and I were working on something else). I only found out later after it was released!
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That's super impressive. I remember being astonished that the x86 executable of Python running through Rosetta 2 on my M1 was just a factor of 2 slower than the native version.
QEMU was something like a factor of 5-10x slower than native, IIRC.
QEMU probably had to account for differences in memory models. A fork with that stuff removed might be able to easily catch up.
QEMU loses a bit from being a generic translator instead of being specialized for x86->ARM like Rosetta 2, Box64 or FEXEmu. It does a lot of spilling for example even though x86 has a lot fewer registers than aarch64.
Flags are also tricky, though they're pretty well optimized. In the end the main issue with them is also the spilling, but QEMU's generic architecture makes it expensive to handle consecutive jump instructions for example.
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That is fascinating that this amazing system was the work of largely one person. You mentioned that interacting with the OS was super difficult. What were the most enjoyable aspects of building Rosetta?
I am also amazed that this was the work of largely one person. Having seamless and performant Rosetta 2 was a major factor why the Apple transition from Intel to Apple Silicon was viable in the first place!
It's a shame that Apple's stated intent is to throw the project away after a while. Personally, I really hope it sticks around forever, though I'm not optimistic.
Rosetta 2 can't go away until Apple is ready to also retire Game Porting Toolkit. At most, they might drop support for running regular x86 macOS applications while keeping it around for Linux VMs and Windows applications, but that would be pretty weird.
In principle, the Linux Rosetta binaries should remain usable well into the future. Even if Apple discontinues support for Rosetta in their VMs, there's very little (beyond a simple, easily removed runtime check) preventing them from being used standalone.
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> game porting toolkit
I don't understand why Apple even bothers these days, I wouldn't be surprised if Apple's gaming market is a quarter of what the Linux gaming market currently is (thanks to Valve and their work on proton and by extension wine)...
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Where did Apple state that Rosetta 2 was to be deprecated?
I think they assuming from the past that this will happen. When Apple moved from powerPC to x86 there was Rosetta 1. It got deprecated as well.
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