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Comment by rbanffy | Hacker News Reader

Richard Gabriel was right. Unix is good enough and few people care whether HURD has some nicer features that can be implemented in the wrong layers through piles of clever hacks.

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Indeed. Worse is better, and I use Linux and not Hurd because it does what I need even if it doesn't look shiny on paper.

I'm not convinced that Hurd's translator idea is a hack, or that it's doing it in the wrong layer.

That every program that presents FTP on my system (GNOME, KDE, lftp, Emacs/TRAMP) has to implement its own VFS is a hack, so is having to use iptables or another forwarder if I want to run a non-root daemon on port <1024. And that I have to recompile and reboot if I want to enable some minor feature in the kernel.

EDIT: The last two paragraphs are redundant because I misread rbanffy's reply, and I oddly can't reply to his new one so I'm putting this here.

No. HURD's translators are the right idea. The hack is reimplementing VFSs at the GUI level.

Certainly the existence of the KDE-specific virtual file system is a terrible thing...

I really saddens me Plan/9 went nowhere (parts of it went everywhere ;-) )

I am uncomfortable having what amount to be sci-fi versions of Unix and VMS to chose from. What would be a cutting-edge, legacy-free OS these days?

Exokernels: http://pdos.csail.mit.edu/exo.html

Though sadly this page is from 1998. But there are some people who are still working on Exokernels. You can meet them here at HN.

I am quite involved with virtualization. The interesting thing is, that some people are now running their software on the virtualized bare metal--i.e. using the hypervisor but without an operating system.

This is essentially treating the hypervisor as an exokernel operating system. And it seems to become more common.

Perhaps we are really coming to exokernels in a very roundabout way.

But not at all as a general computing environment. It makes sense once you have your application finished that you could move it to a kernel that has just what you need. However, it makes no sense when you start development to try to guess what calls you might end up using.

But you can go the Smalltalk-style route. You write your app and then use a tool to pare down the environment (kernel included) to just what you use and nothing else.

Indeed. It'll be interesting to see if people use Maxine VM a lot to run Java stuff on a xen/micro-kernel environment.

The HotSpot style C1X optimizing compiler for Maxine is under heavy and constant development right now, I wouldn't be too surprised to see it ready for that sort of thing fairly soon as these things go.

You can use it as a general computing environment.

> However, it makes no sense when you start development to try to guess what calls you might end up using.

I agree. That's why you will be using libraries to duplicate what your OS did for you. The Exokernel guys call this a library OS. Libraries are already quite good at providing abstractions.

The difference to a conventional architecture is, that the kernel only provides secure multiplexing between application on the same machine. But the abstractions from the hardware are provided by some libraries. It's easier to experiment with libraries than with operating systems.

The MIT-Exokernel-Operating-System page (http://pdos.csail.mit.edu/exo.html) explains this in more detail. If you look at the first picture, and replace `Exokernel' with `hypervisor', you get modern virtualisation.

I'm semi-intrigued, but I'd like to see a sign of life beyond a page from '98. Not trying to be cruel, just saying that'd I'd like to see what's going on now.

The signs of life are the current developments in the virtualization world. The original MIT Exokernel effort may be dead, as far as I know.

Yep, this is really cool. I don't remember what it was called, but didn't Sun do something like this, where the JVM basically interfaced directly with Xen?

I see exokernels as the future, but I'm slightly biased, as I'm involved with one...

GuestVM: http://labs.oracle.com/projects/guestvm/

Still an active project as far as I know. Mick Jordan has as of late been hacking on Maxine and I've seen GuestVM related commmits in Maxine.

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