[ludocode]

> Cosmopolitan only depends on stable kernel ABIs with long term stability promises

Unfortunately, on macOS a stable kernel ABI does not exist. macOS has had kernel ABI breakage before, even recently, and they explicitly warn against making your own system calls. On Windows things are more stable but that's only because Windows cares about backwards compatibility to the point of preserving the behavior of even the most badly written software.

Linux is the only one of the three that promises a stable kernel ABI. On macOS and Windows the system libc is the only safe way to talk to the kernel.

[moonchild]

Ntdll is the kernel ABI on windows; it is stable, and cosmopolitan uses it.

Not sure what you mean by ‘on Windows thing are more stable’; syscall numbers change all the time. See https://j00ru.vexillium.org/syscalls/nt/64/

[jart]

Cosmopolitan uses the stable WIN32 API on Windows. The word ABI is used loosely in this context. It's somewhat accurate since Cosmopolitan still configures the assembler to generate the binary linkage by hand. NTDLL APIs are only used on rare occasions, such as sched_yield(). When it is used, it's used in accordance with Microsoft's recommendations: namely having fallback. It'd be great if we were authorized to use the SYSCALL instruction on Windows, however we have to respect Microsoft's recommendations if we want long-term stability promises.

Mac however is a different story. One of the reasons Apple came back is they adopted the UNIX interface. They literally copied the magic numbers right out of the UNIX codebase. They shouldn't have the right to stand on the shoulders of giants, pull an about face, and then declare it their own internal API. Apple actually broke every single Go application a few years ago by doing that, and I'm astounded that Google didn't do more to push back. We need to give Apple as much feedback as possible about keeping the SYSCALL interface stable. It's the right thing to do.

[pjmlp]

They didn't had to copy anything, NeXTSTEP already did it by having a FreeBSD kernel copied into their hybrid kernel.

That doesn't mean it is going to stay like that forever, the UNIX network stack is already considered legacy for modern code.

https://developer.apple.com/videos/play/wwdc2017/707/

https://developer.apple.com/videos/play/wwdc2017/709/

Also I have some doubts about support in non-POSIX OSes like IBM i, z/OS, ClearPath MCP, or RTOS like INTEGRITY.

[asveikau]

Microsoft documents ntdll as subject to change and makes no promises not to break it. When I was at MS it was advised not to use it for things that ship outside Windows. They had automated scripts to flag such a use.

In practice it is pretty stable, and many use it. Many things cannot be changed without causing massive internal refactors and app compat issues. But it is regarded as internal.

[pjmlp]

Ntdll is not meant to be used as public API, whatever works does so by pure luck.