Linked by Thom Holwerda on Sun 16th Apr 2006 15:36 UTC
OSNews, Generic OSes Right in between a car crash and Easter, I knew I had to write a Sunday Eve Column. So here I am, digesting vast quantities of chocolate eggs (and I don't even like chocolate), craving for coffee (for me about as special as breathing), with the goal of explaining to you my, well, obsession with microkernels. Why do I like them? Why do I think the microkernel paradigm is superior to the monolithic one? Read on.
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I'm sorry, but if I have to choose between believing you in saying NT did not start out as a muK, and andy Tanenbaum saying it did, I prefer the latter. No offense.

Look Thom, I've read most of the available windows internals literature, even that leaked W2K source code, spent countless hours disassembling NTOSKRNL.EXE and even reported some kernel bugs to MS lately, and found absolutely no proof that NT was ever to be or has been a microkernel. Function calls between various executive components are so interleaved that there is absolutely no chance of decoupling them. Ever.

Noone questions Mr. Tanenbaum's authority on general OS design theory, distributed systems, compiler and automata theory etc. - but I think that in this case, he fell on MS's marketing crap. Heck, even Cutler said they're building something different from RSX-11M (which was a microkernel).

Read the relevant literature (Russinovich/Solomon is great for starters), or check out the discussions on this "microkernel issue" on

That's a subjective matter. A kernel is hybrid when it combines both worlds; some parts live in kernelspace, while others do not. Exactly what goes into kernelspace has absolutely nothing to do with it.

Oh, it certainly has. "Hybrid microkernel" is in this context so vaguely defined term it can be applied on any OS you like. Let me put it like this: NT has inside kernel-mode (ring0) almost anything that traditional monolithic *nix kernels (Linux, Solaris, *BSD etc.) have + GUI. So can anybody tell me what the hell is so microkernelish about it, that other monolithic OSes don't have, so that it can be entitled as "hybrid microkernel"???

And since NT is very flexiable and modular, they can move stuff in and out of kernelspace relatively easily

No they can't ;) I would really like to see a hacker capable of putting, lets say, Object Manager, inside user-mode server process and routing all handle-checking logic via IPC on it :-)

(hence the GUI in Vista will live in userspace again).

I thought we've demistifyed that one..

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