At least one of the L4 implementations. IBM's K42. I think one of the windows kernels tried it once then reverted? Or did every single windows kernel use C too?

At least one of the L4 implementations. IBM's K42. I think one of the windows kernels tried it once then reverted? Or did every single windows kernel use C too? Symbian really hit a wall taking Nokia down with it. The N95 was well established in the market before the iphone hit but they couldn't get the slow out. Blame it on C++, something else, whatever. C++ is fine for systems code done tastefully. GDB, GCC, libc, java, go nuts! Kernel, not so much. There's a few things going on. You have to agree on a subset of C++ which is a royal bloody pain in the backside at best. It's like a bracing style meeting where the issues actually matter. Some of this is decided for you, you can't have exceptions. Now you can't have operator overloading either. Now constructors are a bit of an issue to consider fairly deeply, "YOU'RE KIDDING YOU'RE SO WRONG I HATE YOU!" And I don't even know what you think about it yet! ;-) Now do that with thousands of contributors. Nasty. Google and Fuchsia? I think they've already got rid of most contributors with the CLA. https://cla.developers.google.com/about/google-individual https://cla.developers.google.com/about/google-individual I couldn't find an actual license and didn't feel like curling to bash to find out what's in the code. It's not surprise that most who try it have a microkernel based system. It is doable. It's been done! Criticising Linus for refusing to go that way seems a little naieve to me tbh. He can point at considerable success as a result of his fundamental approach. That may not be the end of it. But it clearly wasn't a disaster. Critics haven't managed to achieve the success the early days of linux yet as far as I'm aware. C++ compilers have universally sucked incredibly hard until fairly recently when gcc and clang really lifted the standard. No the crooks at intel and the way they sabotaged their customers to make their competitors look bad do not count. They lost the right to be taken seriously at that point. C++ for cross platform has been horrible until very recently. A = B + C + D; You know exactly what that does in C without thinking. C++ not so much. Having those extra layers of thought required between the reader and the machine is unpleasant for OS stuff. C++ has its place. Many of its features are extremely useful and seductive. Many can be used tastefully in userspace to make better, stronger, more reliable code. The Kernel? I don't see it . You want to do dynamic dispatch in C. You can see exactly how that will work on the machine. Virtual functions. No, there's magic there. The implementation isn't guaranteed and can change. There are simply more corner cases, gotchas, foot guns and nastiness where you really don't want it. Kernels are hard enough.