> But if you’re willing to do that, then the application is basically acting as its own kernel... so why not just admit that, and instead of writing a user-spac

> But if you’re willing to do that, then the application is basically acting as its own kernel... so why not just admit that, and instead of writing a user-space process that has half the features of a kernel, just either 1. write your logic as a Linux kernel driver, or 2. compile your program into a unikernel framework? Because the kernel is still a lot of other things for you other than networking - I think it's a stretch to say that all user-space networking makes your work "half" of that of a kernel. And, you're not necessarily the one doing it. You may be an application, and your user-level TCP (including kernel bypass) may be a library from someone else. But to your general point of now you are now well past the city walls, and may run into trouble, I agree. I assume that this sort of thing is only done by a small number of people.