[int_19h]

> On the contrary if you want to reimplement a BSD you need to reimplement their libc (and perhaps some other libraries)

To clarify, what you're saying is that in BSD land, the syscall API is not considered stable, but libc is?

[Manozco]

I'm not ultra familiar with the topic so if someone wants to correct me please do but :

- Linux has always been described as just a kernel, which translates as just a syscall table. The fact that this table is stable or not is not relevant here.

- *BSD on the other hand are shipping a kernel plus a lot of libraries/binaries, if you want to simulate a BSD system, you have to expose those libraries/binaries.

It's not so much a technical difference, it's more of a different approach to OS development (kernel space vs kernel/user space).

[int_19h]

Thing is, if syscalls in BSD are considered stable the way they are in Linux, then you could just ship your own kernel with BSD's libc. But if they consider it an internal API between kernel and libc, and apps are only ever supposed to depend on libc, then of course that doesn't work.

So stability of syscall API is the de facto differentiating factor here. It sounds like Microsoft couldn't do "Windows Subsystem for BSD" the way it did WSL, for example.