In large part what a modern Unix-like operating system is... is a kind of emulator that makes the very insanely complicated and powerful machines of today look

In large part what a modern Unix-like operating system is... is a kind of emulator that makes the very insanely complicated and powerful machines of today look as simple and understandable as a PDP/11. I think of the Linux kernel (in conjunction with some complicated hardware support) as a giant behemoth of code there to maintain the illusion of a set of relatively understandable clean abstractions: memory, tty, display, network, process, user, file system. None of those things are nearly as simple as the mental model we maintain of them, but the OS makes it look that way. They're actually insanely complicated underneath because of real world reasons. The code in the kernel is in large part there to hide that. That code wasn't needed in early operating systems because the underlying hardware system actually was that simple. ... But with hypervisors on the scene now, and virtualization the common way to run applications in the "cloud", it's now entirely conceivable that the "unikernel" type approach could create bespoke software systems out of only the pieces needed for a given application or service on a given platform, and ditch the rest. The win is potentially a more holistically understandable system, in addition to the potential for targeted optimization.