[panzi]

Is NTSYNC used for anything else other than wine/proton?

[12_throw_away]

The docs explicitly say not to: https://docs.kernel.org/next/userspace-api/ntsync.html

[le-mark]

One wonders if it uses futex and poll under the hood, why not?

[shoo]

Doubt it. No linux-native application would be designed to use a Windows API.