Re: Some questions
On Thu, Oct 28, 1999 at 12:58:10PM +0200, Gergely, Zsombor wrote:
> Some questions came into my mind, as I browsed the Hurd infos. I am absolutely
> no programmer, just someone who uses Linux for "production", so do not laugh at
> them.
Your questions show a lot of understanding. If you are not a programmer, you
should become one :)
> 1) Am I right if I think that a microkernel has nothing to do with small size?
Yes. Design is much more important. Still, Mach is not as big as it looks
like. Brent explained that already. Both kernels should be compressed before
comparing (linux always is, gnumach can be compressed with gzip). To get an
idea, compile linux 2.0.36 with all block device drivers and network card
drivers.
That said, Mach is still a beast. Modern microkernels are much more micro.
> Although Mach and the servers are not _really_ big (like NT), they seem to be
> bigger than Linux (and modules) for the first sight. How will this (and the
> advantage, that the whole system is in several parts) affect its applicability
> in - say - embedded devices?
We are not sure. I think for embedded systems, linux has much more chances
to succeed currently. Later, if we switch to a really tiny microkernel, you
won run a ext2fs server for a tumble dryer, so it is just a question of
writing a small translator/server.
> 2) You say it is good to put the servers in user space. Is it the same as user
> space vs. kernel space? If I understand well, the separation provides memory
> protection as well (crashes, garbage in memory). If yes, don't you loose
> something with not separating?
Yes indeed. It user/kernel space with all protections you want in the user
level and no protection in the kernel level. I don understand your question,
though. What should we seperate?
> 3) If there is no centralization in the kernel, how can a developer make such a
> server that is transparently usable for those softwares, that are not explicitly
> designed to support the new features. In other words: if there is nothing like
> the kernel release (and syncing) in Linux, what makes the _whole_ thing
> coherent?
Not much. it the idea that every user can build up his own system on top.
So, if you want to operate, start compatible servers. It's after all your
decision, much like it is your personal decision if you use one desktop
system (like Gnome) or Xlib, Athena etc programs together. Latter don't
interoperate well (drag&drop etc). As they run in user space, you can tweak
the system to your liking, even as a user.
But there are still some servers that are the base of the Hurd system.
Thosee are the auth, proc, init and password server at least. You don need
to register your process with the proc server (and it won show up in the
output of "ps" if you don do so), but that the only thing that will give you
access to the features of the proc server. Same with auth. If you don use
auth, your tasks will have little to none privilegdes.
> 4) Is it possible to develop a translator that turns the ext2 filesystem to
> something like the one of the "Be"? If I have seen it well, it can record
> auxiliary data for a file regarding to the author, the topic, the project it is
> a part of.
Yes, it is possible. You can (if you can) write ext2fs->beos converter and
simply put it on a ext2fs partition. If a user has permission to access
/dev/???, the suer can start this translator in his user space without
consulting the admin, compiling a new kernel or anything.
However, do you really want that? That a difficult question.
> 5) Can something like a "database filesystem" created? Something than can
> produce views of the underlying files according to properties (like above). Like
> a directory with all my data files, one with all my documents, one with all my
> programs, and just another with data per preject. Doing this with symlinks is a
> nightmare (updating).
Of course. It all up to you. Everything that you can squeeze into a
filesystem is doable.
> 6) Will the Hurd be ready (to the extent like Linux is now) when Debian releases
> 2.2? When will it get PCMCIA support?
No. We will need more time. The more people help, the less time we need :)
PCMCIA is coming, at least rudimentary. Thomas has a laptop, so it is a
higher priority now :)
> 7) I am Hungarian and miss the keyboard layout very much. Is it available? If
> not, can I make one? Please let me know...
You can hack something that will work. I will sent you the files you need
later today. However, for the clean and permanent solution, Kalle is writing
a real console translator which will be localized then.
Thanks,
Marcus
--
"The purpose of Free Software is Free Software.
The End and the Means are the same." -- Craig Sanders
Marcus Brinkmann <Marcus.Brinkmann@ruhr-uni-bochum.de>
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