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Comment by fold3 | Hacker News Reader

Do you think it would eventually be possible to run amd64 programs on it (like rosetta2 but for Microsoft Windows?) The main feature of Windows is legacy compatibility and that is perhaps why arm Windows doesn't seems to gain much traction. Eventually I wonder if this project could be helpful to run wine on asahi linux, which would be awesome.

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Windows on ARM supports that already[1]. The low traction is probably because of the (sorry) bad hardware. Windows branded ARM as the budget option so nobody wanted it. Then Apple came along and flipped the script.

[1]: https://blogs.windows.com/windows-insider/2020/12/10/introdu...

It’s not just that the hardware was lacking, there was no good solution for running x86 binaries. ARM windows has no Rosetta.

ARM Windows (it was actually always THUMB2 Windows) was officially discontinued as of RT, without ever getting the x86_32 emulator let alone the x86_64 one.

But unoffically, there is a leaked build of Windows 10 15035 for ARM32, and it's possible to sideload it onto an original Windows RT device.

The x86_32 emulator was present in the ARM64 Windows release by this point, but, i don't know if the leaked ARM32 release includes an ARM32 version of the x86_32 emulator.

Project developer here, Windows actually has a x64 compatibility layer now for ARM64 systems in general, so any ARM64 Windows device should be able to run x64 apps (granted the performance penalty is worse than Rosetta since Rosetta relies on Apple SoCs actually implementing small slices of x86 (memory ordering model for instance) which isn't true for any Qualcomm SoC at the moment.)

The problem with x64 on arm64 is no longer if it's possible, but rather the performance penalty. As for whether I'll try to make a Rosetta-like compat layer using the hardware optimizations: not sure yet, I have bigger fish to fry before I get there.

It turns out Rosetta2 does not rely on special M1 hardware memory ordering at all:

https://twitter.com/never_released/status/153412764108259328...

https://twitter.com/marcan42/status/1534032369166225409

The baseline for translation is qemu-user, but other pure-software emulators like FEX-emu and Box86/Box64 can perform this translation significantly faster. So I think there's just ordinary performance engineering to close the gap.

Yes it does, you’re misunderstanding the tweets. You need TSO to emulate x86-64 correctly.

Arm windows already has that functionality.

amd64 programs on Windows for ARM already work almost as well as intel mac apps do on an M1 mac with Rosetta2. Even in case of amd64, on Windows for ARM, on Parallels for M1 MacOS! This was true even 1 year ago.

I think Windows for ARM is still suffering from a previous release several years ago without the equivalent of Rosetta 2, and since then no hardware that actually offers an advantage in terms of battery life in the same way M1 macs did.

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