Genuine question - are there examples (research? old systems?) of the interface to the operating system being exposed differently than a library? How might that work exactly?
> examples ... of the interface to the operating system being exposed differently than a library
Linux syscalls, MS-DOS 'software interrupts'...
But that's not the issue, operating system interfaces can be exposed via DLLs, those DLLs interfaces just must be guaranteed to be stable (like on Windows).
Tbh, I'm not sure why I can't simply tell the gcc linker some random old glibc version number from the late 1990s and the gcc linker checks whether I'm using any functions that haven't been available in that old version (and in that case errors out). That would be the most frictionless solution, and surely it can't be too hard to annotate glibc functions with a version number in the gcc system headers when that function first appeared.
