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Given that Apple control their own CPU designs, how hard would it be for them to add a hardware x86 ISA emulation layer over their ARM CPU for use with MacOS?

Given that Apple control their own CPU designs, how hard would it be for them to add a hardware x86 ISA emulation layer over their ARM CPU for use with MacOS? That way the OS and newer software could be compiled for ARM, and legacy software could be run in x86 mode with reasonable performance without the need for rosetta-style emulation.

vertex-four 10y ago
So many patents involved in implementing x86 efficiently, that Intel have no interest in sharing at prices that would make this make any sense.
- threeseed 10y ago
  They don't need to work with Intel. Apple could just buy Parallels.
  - vertex-four 10y ago
    Implementing a software VM is different from implementing a hardware ISA.
  - luma 10y ago
    Parallels is performant because it isn't emulating the entire processor. Most instructions are passed through to the underlying hardware without translation.
    - TazeTSchnitzel 10y ago
      Current Parallels is an x86 virtualisation product, yes. But it used to be an x86 emulation product.
  - snowwrestler 10y ago
    Or AMD
DeepYogurt 10y ago
There's a company called transmeta that tried this. It didn't work well. Apple is big enough that major software vendors will deal with it.
- Zardoz84 10y ago
  If I remember correctly, Transmeta used a VLIW CPU where there is a low level firmware doing translation from x86 (or what do you need) to the native ISA.
  - acdha 10y ago
    Yes – that “Code Morphing System” had a complex layered process where code started running in an interpreter and was progressively optimized as it was repeatedly executed. The main problem they hit is that even with a simplified CPU, the economies of scale are brutally unforgiving to a niche product and they could never demonstrate a compelling advantage to prospective buyers: there were a few microbenchmarks where it looked competitive but real world code never showed much benefit and the larger engineering teams Intel/AMD could afford to support continued to race ahead. In the case of Apple, the situation could be different because they're guaranteed to ship in significant volume, their potential budget for R&D is massive, and most importantly they control the entire OS and have significant sway with the application developers, not to mention how far dynamic binary translation has improved. It'd still be a huge project but it's not unrealistic to image something like running a slow, offline binary translator over the entire contents of the App Store, which simply wasn't the kind of thing anyone could do in the 90s.
threeseed 10y ago
Or Apple could just take the hit on margins for a while and ship both ARM and Intel CPUs in the same machine. Whilst Apple does have an excellent history with these transitions using software I suspect in this situation hardware might be easier/better.
raverbashing 10y ago
> hardware x86 ISA emulation layer over their ARM CPU That's just asking for trouble, and making their chip consume more It will be done in software

vertex-four 10y ago

So many patents involved in implementing x86 efficiently, that Intel have no interest in sharing at prices that would make this make any sense.

threeseed 10y ago
They don't need to work with Intel. Apple could just buy Parallels.
- vertex-four 10y ago
  Implementing a software VM is different from implementing a hardware ISA.
- luma 10y ago
  Parallels is performant because it isn't emulating the entire processor. Most instructions are passed through to the underlying hardware without translation.
  - TazeTSchnitzel 10y ago
    Current Parallels is an x86 virtualisation product, yes. But it used to be an x86 emulation product.
- snowwrestler 10y ago
  Or AMD

DeepYogurt 10y ago

There's a company called transmeta that tried this. It didn't work well. Apple is big enough that major software vendors will deal with it.

Zardoz84 10y ago
If I remember correctly, Transmeta used a VLIW CPU where there is a low level firmware doing translation from x86 (or what do you need) to the native ISA.
- acdha 10y ago
  Yes – that “Code Morphing System” had a complex layered process where code started running in an interpreter and was progressively optimized as it was repeatedly executed. The main problem they hit is that even with a simplified CPU, the economies of scale are brutally unforgiving to a niche product and they could never demonstrate a compelling advantage to prospective buyers: there were a few microbenchmarks where it looked competitive but real world code never showed much benefit and the larger engineering teams Intel/AMD could afford to support continued to race ahead. In the case of Apple, the situation could be different because they're guaranteed to ship in significant volume, their potential budget for R&D is massive, and most importantly they control the entire OS and have significant sway with the application developers, not to mention how far dynamic binary translation has improved. It'd still be a huge project but it's not unrealistic to image something like running a slow, offline binary translator over the entire contents of the App Store, which simply wasn't the kind of thing anyone could do in the 90s.

threeseed 10y ago

Or Apple could just take the hit on margins for a while and ship both ARM and Intel CPUs in the same machine. Whilst Apple does have an excellent history with these transitions using software I suspect in this situation hardware might be easier/better.

raverbashing 10y ago

> hardware x86 ISA emulation layer over their ARM CPU That's just asking for trouble, and making their chip consume more It will be done in software