All modern kernels are going to be complicated. Simple kernels aren't efficient or full-featured, that's just how the real world works. I sense a real bias as

All modern kernels are going to be complicated. Simple kernels aren't efficient or full-featured, that's just how the real world works. I sense a real bias as to how module boundaries should be architected here. Right off the bat, saying all modern kernels will be complicated (as opposed to complex) and that simple kernels won't be efficient or full-featured, demonstrates you're thinking squarely in terms of monolithic kernels. Are QNX and L4 not simple, small yet efficient kernels? Complexity is intrinsic, but something being complicated usually implies the use of wrong or incomplete abstractions. Having the right architecture from the beginning can make huge differences, as certain problems either go away or become more manageable as they're shifted into the library or server level, with all the advantages that come from being there. just take a look at the massive amount of work going into kdbus which is being worked on by many different people with different interests kdbus is mostly worked on by the core systemd contributors + Greg K-H, which is a handful of people. The fact that it has been routinely criticized by Lutomirski and others speaks for itself.