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SubjectRe:Linux is a MicroKernal? (was:is linux obsolete)
"G. Allen Morris III" wrote:

> Linux modules are in the same address space as the kernel. In a
> micro-kernel ``modules'' are in their own address space. This is
> why micro-kernels are slower than traditional kernels.
>
> It is because of this slowness that micro-kernels are sometimes very
> large, as in the case of NT. To speed up a micro-kernel you put the
> more important parts into the kernel proper.
>

So what is a microkernel, really? Does putting the GUI into the kernel
invalidate it as a microkernel? Linux, even with modules, is very
squarely in the monolithic camp. It seems to me that the advantages of
a microkernel, as usually presented, are rather weak. I usually hear
something like:

-Well, what if a user wants certain functionality and the administrator
doesn't want to include that into his kernel, since he is very
conservative.

-Only kernel code can crash the machine. So the less of it you have, the
better debugged it can be and the more stable the OS is.

Argument 1 is pretty lame, to my mind. And if the functionality
includes direct access to hardware, its dangerous anyway, and if it
actually requires the *intallation* of new hardware (say a card), then
just try walking in and doing that without the SA's approval.

Argument 2 is only effective if speed problems don't force you to put
things like the gui (which are particularly complex and prone to
problems) in the "microkernel". In this respect, is NT's kernel (which
includes a GUI if I am not mistaken) really any more of a microkernel
than the Linux kernel? Linux does its GUI stuff in user space.

This brings a question to mind. MS claims that 60% (I think) of NT
crashes are due to third party drivers, not the OS itself. Where do
drivers live in a microkernel based system? And also, more
specifically, where do they live in NT?

Also, is this still an issue in 1999?

This is not intended as an NT bash. I have no love for NT, but please
view this as a request for info, not a bash.

-Thanks,
-Steve

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