From what I have read on operating systems, the impression I have been receiving is that, for at least 30 years, "everybody has known" that microkernel-based operating systems are "better" than monolithic operating systems. And yet, I have a Linux OS at work and am typing these lines on a computer running a Windows OS at home. Moreover, looking at Wikipedia's list of microkernel-based operating systems, it seems most are old and have been discontinued, and none have really broken into the PC space (although FreeRTOS is a player in the embedded space).

Question: Why has no microkernel-based OS broken into the mainsteam? Why is the world still using monolithic OS's 28 years after Tanenbaum-Torvalds? What is the "hard problem" microkernel-based OS's have not been able to solve, and why do people keep trying?

1 Answer 1


Yes, you use microkernel operating systems. If you use a modern Intel CPU, it includes a copy of Minix which runs on a separate processor that is embedded in the processor that you think you have. Chances are also very good that at least a few of your peripherals use microkernel operating systems internally.

Moreover, you may not use any of these, but a lot of people use macOS, iOS, iPodOS, audioOS, watchOS, and tvOS. They are distinct (though in some cases related) operating systems implemented on top of the Mach microkernel. Or perhaps they use Horizon, the operating system of the Nintendo Switch.

Google seems to be going that way as well, with Zircon. ChromeOS and Android will probably be based on that at some point in the forseeable future.

Having said all that, the way the server world is going these days, especially in cloud computing, is guest operating systems running under hypervisors, which you can think of as related to the microkernel idea.

  • $\begingroup$ Thanks! Although, as pointed out here, it's debatable whether XNU is even hybrid, let alone multikernel: cs.stackexchange.com/a/49978/114060 And as for Zircon, why should I expect a different fate for it than for any of its predecessors- namely that after a few years Google will shut it down, or will use it only for one fairly narrow class of devices? $\endgroup$ Commented Jan 6, 2020 at 6:11
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    $\begingroup$ It is debatable, yes, and the boundaries are fuzzy. I think of XNU as hybrid, and specifically it is a monolithic executive on top of a microkernel, but I also acknowledge that "hybrid" may not mean very much these days. At any rate, it resembles Digital UNIX and NeXTSTEP closely enough... $\endgroup$
    – Pseudonym
    Commented Jan 6, 2020 at 23:11

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