Linus replies. Re: Computer: Can We Make Operating Systems Reliable and Secure?

[Donnie Jones]

Hello,

I am a lurker on this list, but since Tanenbaum got to voice his opinion, 
I figured I would forward on the related reply by Linus.

Link:
http://www.realworldtech.com/forums/index.cfm?action=detail&PostNum=4342&Thread=12&entryID=66630&roomID=11

Excerpt from the post by Linus:
********
The fundamental result of access space separation is that
you can't share data structures. That means that you can't
share locking, it means that you must copy any shared data,
and that in turn means that you have a much harder time
handling coherency. All your algorithms basically end up
being distributed algorithms.

And anybody who tells you that distributed algorithms
are "simpler" is just so full of sh*t that it's not even
funny.

Microkernels are much harder to write and maintain
exactly because of this issue. You can do simple
things easily - and in particular, you can do things where
the information only passes in one direction quite easily,
but anythign else is much much harder, because there is
no "shared state" (by design). And in the absense of shared
state, you have a hell of a lot of problems trying to make
any decision that spans more than one entity in the
system.
********

I am very new to kernel development, but I do currently work with 
distributed algorithms and I find Linus argument that microkernels are 
more complex very interesting, what do you guys think?

Sorry if this may be off-topic.  :-)
Enjoy.
__
Donnie


On Sat, 6 May 2006, Thomas Schwinge wrote:

> Thomas Schwinge (tschwinge@gnu.org) has forwarded this article from
> Computer
>
> Can We Make Operating Systems Reliable and Secure?
>
> Sender's message:
> Hi! You might be interested in reading this article by Tanenbaum, Herder
> and Bos. There's no fundamental news in it, but a nice overview why they
> (and we!) are doing, what they're (we're) doing. It also gives a short
> introduction about the basic concepts of the microkernelized Minix 3 and
> Microsoft's Singulatiry. Regards, Thomas
>
> >> Click here to view this article.
>
> Released:     01 May 2006
> Posted on:     Computer
> Computer is a publication of the IEEE. (C)2005. All rights reserved.