In article <1992Aug29.115034.17334@hacker.UUCP> steve@hacker.UUCP (Stephen M. Youndt) writes:
quoted text
>kernel as opposed to a "micro" kernel. It just seems that the micro kernel
>people are the only ones doing it (for Unix anyway; VMS can hardly be
>considered a micro kernel).  Well, that's my $.02 worth.
>


Actually, AIX has loadable device-drivers and loadable kernel
extensions.  And AIX is certainly not anything like a micro-kernel.

I think you're absolutely right about loadable device-drivers, and in
fact, they make more sense on the PC class machines than on ones that
run VMS.  There is a far greater variety of devices available for PCs
and the resources available (memory) is usually much less.  A fat
kernel with every likely device driver can be tolerated better on
systems with 64Mbyte plus systems than on our "poor" machines with
8Mbytes and often less.

I've spent the last few years of my life working on micro-kernels,
Mach in particular, and came to the conclusion that there's no magic
here.  It's like the C++ vs. C debate.  There's a lot of stuff that is
elegant to do in C++, but you can also approximate them in C and maybe
the performance tradeoff is serious.  As machines get faster, the
performance tradeoff issue becomes less important and the elegance
becomes much more important.  Perhaps similar issues hold true with
micro-kernels vs. the traditional approach.

Basically, there's no magic way to get neatness, and neatness is
possible with the traditional macro-kernel.
-- 
rajat (rajat@watson.ibm.com)