Reply to post: Both Windows and Linux are monolithic kernels

One Windows? How does that work... and WTF is a Universal App?

DougS Silver badge

Both Windows and Linux are monolithic kernels

Being able to load/unload drivers don't make a microkernel. Having drivers run in userspace is (one of several) minimum requirement for a microkernel. Neither do that, both run drivers in kernel mode. Microsoft doesn't even make the display driver loadable, they gave up on that back in the early NT days because it hurt performance, and paid for it with years of BSODs until the display drivers got more stable.

Calling Windows a "hybrid kernel" is laughable, there is no such thing. That's like saying "she's partially pregnant". You either have a microkernel or a monolithic kernel, there is no in-between except for Microsoft apologists who don't want to admit that the original NT concept of a microkernel was never realized because they couldn't make it perform well.

If Windows has a hybrid kernel then OS X's / iOS's XNU a microkernel by comparison. At least it uses a few more microkernel features like message passing instead of shared address spaces. But it doesn't qualify as a microkernel either.

The only true microkernel in mass market PCs / mobile devices I'm aware of is the L4 microkernel running on the security co-processor in the iPhone 5S / 6. That's only because for security purposes you want the privileged portion to be as tiny as possible, and L4 is certainly tiny, and the performance penalty of a microkernel isn't a concern for this use case.

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