I'm just not sure they're all advantages for a general purpose kernel. Many have tried the microkernel model - Windows (NT) and OS X as two examples were both designed around the microkernel model, but have had to give it up since then purely for performance reasons. The high overheads of all the IPC meant that the operating system was just a bit slow, and the IPC made it all hard to debug.
Sorry for the confusion - that's what I meant. They both vaguely work around the microkernel architecture, except where it's not desirable for performance reasons - so for example on my Mac basically every hardware driver runs in supervisor mode.
I agree with the premise that it's more hackable, though.
It states that the Mach kernel used in OSX was Mach 2.5 which was not a micro-kernel (as opposed to Mach 3.0) and is not used in OSX as a micro kernel.
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I'm just not sure they're all advantages for a general purpose kernel. Many have tried the microkernel model - Windows (NT) and OS X as two examples were both designed around the microkernel model, but have had to give it up since then purely for performance reasons. The high overheads of all the IPC meant that the operating system was just a bit slow, and the IPC made it all hard to debug.
it seems that to say that OS X was designed around the microkernel model, but had to give it up is misleading.
XNU, OS X's kernel, is based on the Mach microkernel, but also leverages some monolithic design in some cases.
In any case, it seems that Debian GNU/Hurd would be a worthwhile place to experiment with such technologies with a familiar runtime.
Sorry for the confusion - that's what I meant. They both vaguely work around the microkernel architecture, except where it's not desirable for performance reasons - so for example on my Mac basically every hardware driver runs in supervisor mode.
I agree with the premise that it's more hackable, though.
According to this: http://www.roughlydrafted.com/0506.mk3.html
It states that the Mach kernel used in OSX was Mach 2.5 which was not a micro-kernel (as opposed to Mach 3.0) and is not used in OSX as a micro kernel.
Good thing that with modern computers and better memory management those IPC issues are largely negated in this day and age.
That was a long long time ago.
QNX, Symbian, Type 1 Hypervisors, OKL4 are just a few examples of successful commercial use of the microkernel model.