Kernels- Monolithic and Micro

[The Grunt]

I know this isn't really a newbie question but I don't know where else this would go other than misc, but oh well I put it here :P

I was just wondering if someone could explain the difference between monolithic kernels and the other kind (I think it's micro or something like that). I know that *nix is monolithic and that NT based systems are micro or whatever and I was wondering if someone knew of a writeup or could simply compare and contrast them in a little bit of depth so I could get a basic idea of what they are.

Thanks.

[gore]

Not all UNIX OSs are Monolithic. The Gnu Hurd or whatever is Micro.

The main differences....Well, a monolithic Kernel like Linux is one big entity, where a micro kernel is a bunch of small ones. Kind of like servers that talk to, and communicate with, each other. Micro Kernels are a pain in the ass to code because if one server breaks, you might as well pull the bottom card out of a card house. Monolithic Kernels are much easier, and I don't like Micro Kernels.

Again, Micro Kernels are a pain in the ass, and as Richard Stallam put it "If one part breaks, you have to try and fix it, and while you're doing that, make sure you don't break another part, because this service talks to this one, and that one this one". See the idea?

Not to great of an idea is it?


Another way to learn would be of course using a search engine and looking up the differences. I'm sure there are way more than what I listed.

[The Grunt]

I did some hardcore googling (kind of, heh) and found a few good things buried in the rubbish.

http://encyclopedia.thefreedictionar...ithic%20kernel (this one gave the best technical description IMO)

http://www.harrysufehmi.com/hs/achie...nt-vs-unix.htm

http://osdev.neopages.net/tutorials/...n.php?the_id=9 (this one gives a good illustration that helped me understand how everything talked to each other and such.)

http://blue.gotdns.com/papers/Modern...System_Design/ (this one has some good diagrams too, also has a good technical description.)

http://www.cbbrowne.com/info/microkernel.html (just reiterates what the above did)

If there is enough interest I might attempt my first tutorial attempting to explain the differences and pros and cons of these 2 types of kernels.

[el-half]

I don't know any commonly used system that uses microkernels but more experimental samples developed at various universities include Clouds, Amoeba and Chorus...if you wanted to do some research on actual operating systems.

[The Grunt]

All the NT/2k/XP versions of windows use a hybrid microkernel...
BeOS (ran by the beheerders if you remember, :P gore) uses a microkernel design.

I will look into those others as well to see what they look like from an engineering viewpoint.

[el-half]

Yes, but non-hybrid ones, Mac OS X is also a hybrid micro kernel. I forgot to mention an important one: Mach.

[the_JinX]

also, doesn't a modularized linux kernel count as a hybrid ??

and what about UML ( user mode linux ) ?

[The Grunt]

Originally posted here by the_JinX
also, doesn't a modularized linux kernel count as a hybrid ??

According to most of those links, yea.

[lumpyporridge]

Check out QNX it is a true microkernel, free for noncommercial use (267MB download with about another 150MB or so for a full desktop suite) It is quite cool , a VERY easy and fast install and configuration. I booted the iso, I had no place to install so it offered to delete what i wanted, formatted the partition and I was up and surfing in probably 20 minutes. It runs about 10% slower than a "normal" *nix. The filesystem and commands look/act like nix, is POSIX compliant, GNU utillitys and such available, but inside is very different. It is pretty much impossible to crash, used a lot on embedded systems http://www.qnx.com/ Very cool stuff , the only bad word i have to say is drivers for graphics cards are not made for high end cards but its not exactly intended for gaming anyways... Its well worth playing with.... The qnx site has a bunch of info on architecture of microkernels, smp and such also which are quite interesting.

[The Grunt]

Sounds interesting enough... I will have to find a **** box to run it on though... I love my 9600XT!!!

It causes a lot of driver problems usually though... I don't mind... Call of Duty, Thief, and UT2k4 all look so pretty I could care less about having to wait a couple of months to have X in some distros...