[porpoisely]

Pretty sure the linux kernel is exclusively C. Actually the major OS kernels are pretty much all C - Windows, FreeBSD, MacOS and other BSD derivatives. The GNU software and utils could be written in C++.

[int_19h]

MacOS is not a BSD derivative when it comes to kernel.

And I'm pretty sure Windows has some C++ in kernel space. It might be limited (no exceptions etc), but that's another matter.