> I'm having a hard time seeing the benefits given the obvious increase in complexity.
What? It's simpler. You remove all the overhead of separating the kernel and app. And that of running a full-featured multiuser, multiprocess kernel for the sake of a single app.
> What features of a full-fat OS do unikernels retain? If the answer is very little because hypervisors provide all the hardware access then it would be fair to say that hypervisor has become the OS and the traditional kernel (a Linux one in this case I presume) has become virtually * ahem * redundant.
What? It's simpler. You remove all the overhead of separating the kernel and app. And that of running a full-featured multiuser, multiprocess kernel for the sake of a single app.
> What features of a full-fat OS do unikernels retain? If the answer is very little because hypervisors provide all the hardware access then it would be fair to say that hypervisor has become the OS and the traditional kernel (a Linux one in this case I presume) has become virtually * ahem * redundant.
Yes, that's entirely fair.