| Kapitel 9. Historische Dokumente | ||
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 8.8. GNU Free Documentation License |  | Kapitel 10. Impressum  |
| Kapitel 9. Historische Dokumente | ||
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| 8.8. GNU Free Documentation License | | Kapitel 10. Impressum |
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: LINUX is obsolete
Date: 29 Jan 92 12:12:50 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
I was in the U.S. for a couple of weeks, so I haven't commented much on
LINUX (not that I would have said much had I been around), but for what
it is worth, I have a couple of comments now.
As most of you know, for me MINIX is a hobby, something that I do in the
evening when I get bored writing books and there are no major wars,
revolutions, or senate hearings being televised live on CNN. My real
job is a professor and researcher in the area of operating systems.
As a result of my occupation, I think I know a bit about where operating
are going in the next decade or so. Two aspects stand out:
1. MICROKERNEL VS MONOLITHIC SYSTEM
Most older operating systems are monolithic, that is, the whole operating
system is a single a.out file that runs in 'kernel mode.' This binary
contains the process management, memory management, file system and the
rest. Examples of such systems are UNIX, MS-DOS, VMS, MVS, OS/360,
MULTICS, and many more.
The alternative is a microkernel-based system, in which most of the OS
runs as separate processes, mostly outside the kernel. They communicate
by message passing. The kernel's job is to handle the message passing,
interrupt handling, low-level process management, and possibly the I/O.
Examples of this design are the RC4000, Amoeba, Chorus, Mach, and the
not-yet-released Windows/NT.
While I could go into a long story here about the relative merits of the
two designs, suffice it to say that among the people who actually design
operating systems, the debate is essentially over. Microkernels have won.
The only real argument for monolithic systems was performance, and there
is now enough evidence showing that microkernel systems can be just as
fast as monolithic systems (e.g., Rick Rashid has published papers comparing
Mach 3.0 to monolithic systems) that it is now all over but the shoutin`.
MINIX is a microkernel-based system. The file system and memory management
are separate processes, running outside the kernel. The I/O drivers are
also separate processes (in the kernel, but only because the brain-dead
nature of the Intel CPUs makes that difficult to do otherwise). LINUX is
a monolithic style system. This is a giant step back into the 1970s.
That is like taking an existing, working C program and rewriting it in
BASIC. To me, writing a monolithic system in 1991 is a truly poor idea.
2. PORTABILITY
Once upon a time there was the 4004 CPU. When it grew up it became an
8008. Then it underwent plastic surgery and became the 8080. It begat
the 8086, which begat the 8088, which begat the 80286, which begat the
80386, which begat the 80486, and so on unto the N-th generation. In
the meantime, RISC chips happened, and some of them are running at over
100 MIPS. Speeds of 200 MIPS and more are likely in the coming years.
These things are not going to suddenly vanish. What is going to happen
is that they will gradually take over from the 80x86 line. They will
run old MS-DOS programs by interpreting the 80386 in software. (I even
wrote my own IBM PC simulator in C, which you can get by FTP from
ftp.cs.vu.nl = 192.31.231.42 in dir minix/simulator.) I think it is a
gross error to design an OS for any specific architecture, since that is
not going to be around all that long.
MINIX was designed to be reasonably portable, and has been ported from the
Intel line to the 680x0 (Atari, Amiga, Macintosh), SPARC, and NS32016.
LINUX is tied fairly closely to the 80x86. Not the way to go.
Don`t get me wrong, I am not unhappy with LINUX. It will get all the people
who want to turn MINIX in BSD UNIX off my back. But in all honesty, I would
suggest that people who want a **MODERN** "free" OS look around for a
microkernel-based, portable OS, like maybe GNU or something like that.
Andy Tanenbaum (ast@cs.vu.nl)
P.S. Just as a random aside, Amoeba has a UNIX emulator (running in user
space), but it is far from complete. If there are any people who would
like to work on that, please let me know. To run Amoeba you need a few 386s,
one of which needs 16M, and all of which need the WD Ethernet card.
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 29 Jan 92 14:12:12 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
I would like to at least look at LINUX, but I cannot, since I run
a 68000-based machine. In any case, it is nice having the kernel
independent, since patches like the multi-threaded FS patch don't
have to exist in a different version for each CPU.
I second everything AST said, except that I would like to see
the kernel _more_ independent from everything else. Why does the
Intel architecture _not_ allow drivers to be independent programs?
I also don't like the fact that the kernel, mm and fs share the
same configuration files. Since they _are_ independent, they should
have more of a sense of independence.
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 29 Jan 92 18:03:01 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <1992Jan29.141212.29636@epas.toronto.edu> meggin@epas.utoronto.ca
(David Megginson) writes:
>
>Why does the
>Intel architecture _not_ allow drivers to be independent programs?
The drivers have to read and write the device registers in I/O space, and
this cannot be done in user mode on the 286 and 386. If it were possible
to do I/O in a protected way in user space, all the I/O tasks could have
been user programs, like FS and MM.
Andy Tanenbaum (ast@cs.vu.nl)
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From: gt0178a@prism.gatech.EDU (Jim Burns)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 03:39:48 GMT
Organization: Georgia Institute of Technology
in article <12605@star.cs.vu.nl>, ast@cs.vu.nl (Andy Tanenbaum) says:
> The drivers have to read and write the device registers in I/O space, and
> this cannot be done in user mode on the 286 and 386. If it were possible
> to do I/O in a protected way in user space, all the I/O tasks could have
> been user programs, like FS and MM.
The standard way of doing that is to trap on i/o space protection
violations, and emulate the i/o for the user.
--
BURNS,JIM (returned student)
Georgia Institute of Technology, 30178 Georgia Tech Station,
Atlanta Georgia, 30332 | Internet: gt0178a@prism.gatech.edu
uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt0178a
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From: joe@jshark.rn.com
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Summary: Is this for real?
Date: 31 Jan 92 12:55:21 GMT
Organization: a blip in entropy
In article <12605@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <1992Jan29.141212.29636@epas.toronto.edu> meggin@epas.utoronto.ca
(David Megginson) writes:
>>
>>Why does the
>>Intel architecture _not_ allow drivers to be independent programs?
>
>The drivers have to read and write the device registers in I/O space, and
>this cannot be done in user mode on the 286 and 386. If it were possible
>to do I/O in a protected way in user space,
[[We must be talking about protected mode]] *THIS IS UNTRUE*
The Intel architecture supports independent tasks, each of which can be
given a "i/o privilege level". The convenient approach, used by iRMX(?), is
to "build" a load image ("root" device driver, kernel, MM and FS). Once
booted, these could be replaced by loadable tasks from disc (or network...)
and given a suitable privilege level.
The '386 additionally allows each task to have an "i/o permissions bitmap"
which specifies exactly which ports can be used.
(See "80386 Programmers Reference Manual", chapter 8)
> all the I/O tasks could have
>been user programs, like FS and MM.
Do you really mean "user programs" and not "separate tasks" ??
Separate tasks, possibly privileged, I'll agree with.
User level programs may be ok for teaching operating system principles, or on
toy computers :-) But a "production" system? Not on my machines!
>Andy Tanenbaum (ast@cs.vu.nl)
joe.
--
joe@jshark.rn.com
uunet!nstar!jshark!joe
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From: drew@anchor.cs.colorado.edu (Drew Eckhardt)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 2 Feb 92 12:17:44 GMT
Organization: University of Colorado, Boulder
Nntp-Posting-Host: anchor.cs.colorado.edu
In article <12605@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <1992Jan29.141212.29636@epas.toronto.edu> meggin@epas.utoronto.ca
(David Megginson) writes:
>>
>>Why does the
>>Intel architecture _not_ allow drivers to be independent programs?
>
>The drivers have to read and write the device registers in I/O space, and
>this cannot be done in user mode on the 286 and 386. If it were possible
>to do I/O in a protected way in user space, all the I/O tasks could have
>been user programs, like FS and MM.
>
>Andy Tanenbaum (ast@cs.vu.nl)
Every 386 TSS has an iopermission bitmap. If the CPL is of a lower priveledge
level than IOPL, the io permissions bitmap is consulted, allowing protection
on a port by port basis.
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From: jonathan@ukmug.uk.mugnet.org (Jonathan Allen)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 07:43:00 GMT
Organization: MUGNET UK Backbone (UKMUG)
In article <12605@star.cs.vu.nl>, ast@cs.vu.nl (Andy Tanenbaum) wrote:
> In article <1992Jan29.141212.29636@epas.toronto.edu> meggin@epas.utoronto.ca
(David Megginson) writes:
>>
>>Why does the
>>Intel architecture _not_ allow drivers to be independent programs?
>
> The drivers have to read and write the device registers in I/O space, and
> this cannot be done in user mode on the 286 and 386. If it were possible
> to do I/O in a protected way in user space, all the I/O tasks could have
> been user programs, like FS and MM.
Surely this could have been done by a minute task just to read/write a
given port address in one message ? The security could have been checked
like everything else using the process table ...
Sure it would not have been at all efficient, but would have given
the independance at a price.
Jonathan
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From: ts@cup.portal.com (Tim W Smith)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 7 Feb 92 01:30:59 GMT
Organization: The Portal System (TM)
Andy Tanenbaum (ast@cs.vu.nl) writes:
> The drivers have to read and write the device registers in I/O space, and
> this cannot be done in user mode on the 286 and 386. If it were possible
> to do I/O in a protected way in user space, all the I/O tasks could have
> been user programs, like FS and MM.
On the 386, you could run the drivers in V86 mode, which sort of counts
as user mode and allows access to I/O registers if the kernel sets things
up to allow this.
Tim Smith
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From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 29 Jan 92 23:14:26 GMT
Organization: University of Helsinki
Well, with a subject like this, I'm afraid I'll have to reply.
Apologies to minix-users who have heard enough about linux anyway. I'd
like to be able to just "ignore the bait", but ... Time for some
serious flamefesting!
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>I was in the U.S. for a couple of weeks, so I haven't commented much on
>LINUX (not that I would have said much had I been around), but for what
>it is worth, I have a couple of comments now.
>
>As most of you know, for me MINIX is a hobby, something that I do in the
>evening when I get bored writing books and there are no major wars,
>revolutions, or senate hearings being televised live on CNN. My real
>job is a professor and researcher in the area of operating systems.
You use this as an excuse for the limitations of minix? Sorry, but you
loose: I've got more excuses than you have, and linux still beats the
pants of minix in almost all areas. Not to mention the fact that most
of the good code for PC minix seems to have been written by Bruce Evans.
Re 1: you doing minix as a hobby - look at who makes money off minix,
and who gives linux out for free. Then talk about hobbies. Make minix
freely available, and one of my biggest gripes with it will disappear.
Linux has very much been a hobby (but a serious one: the best type) for
me: I get no money for it, and it's not even part of any of my studies
in the university. I've done it all on my own time, and on my own
machine.
Re 2: your job is being a professor and researcher: That's one hell of a
good excuse for some of the brain-damages of minix. I can only hope (and
assume) that Amoeba doesn't suck like minix does.
>1. MICROKERNEL VS MONOLITHIC SYSTEM
True, linux is monolithic, and I agree that microkernels are nicer. With
a less argumentative subject, I'd probably have agreed with most of what
you said. From a theoretical (and aesthetical) standpoint linux looses.
If the GNU kernel had been ready last spring, I'd not have bothered to
even start my project: the fact is that it wasn't and still isn't. Linux
wins heavily on points of being available now.
> MINIX is a microkernel-based system. [deleted, but not so that you
> miss the point ] LINUX is a monolithic style system.
If this was the only criterion for the "goodness" of a kernel, you'd be
right. What you don't mention is that minix doesn't do the micro-kernel
thing very well, and has problems with real multitasking (in the
kernel). If I had made an OS that had problems with a multithreading
filesystem, I wouldn't be so fast to condemn others: in fact, I'd do my
damndest to make others forget about the fiasco.
[ yes, I know there are multithreading hacks for minix, but they are
hacks, and bruce evans tells me there are lots of race conditions ]
>2. PORTABILITY
"Portability is for people who cannot write new programs"
-me, right now (with tongue in cheek)
The fact is that linux is more portable than minix. What? I hear you
say. It's true - but not in the sense that ast means: I made linux as
conformant to standards as I knew how (without having any POSIX standard
in front of me). Porting things to linux is generally /much/ easier
than porting them to minix.
I agree that portability is a good thing: but only where it actually has
some meaning. There is no idea in trying to make an operating system
overly portable: adhering to a portable API is good enough. The very
/idea/ of an operating system is to use the hardware features, and hide
them behind a layer of high-level calls. That is exactly what linux
does: it just uses a bigger subset of the 386 features than other
kernels seem to do. Of course this makes the kernel proper unportable,
but it also makes for a /much/ simpler design. An acceptable trade-off,
and one that made linux possible in the first place.
I also agree that linux takes the non-portability to an extreme: I got
my 386 last January, and linux was partly a project to teach me about
it. Many things should have been done more portably if it would have
been a real project. I'm not making overly many excuses about it
though: it was a design decision, and last april when I started the
thing, I didn't think anybody would actually want to use it. I'm happy
to report I was wrong, and as my source is freely available, anybody is
free to try to port it, even though it won't be easy.
Linus
PS. I apologise for sometimes sounding too harsh: minix is nice enough
if you have nothing else. Amoeba might be nice if you have 5-10 spare
386's lying around, but I certainly don't. I don't usually get into
flames, but I'm touchy when it comes to linux :)
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 13:44:34 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <1992Jan29.231426.20469@klaava.Helsinki.FI>
torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) writes:
>You use this [being a professor] as an excuse for the limitations of minix?
The limitations of MINIX relate at least partly to my being a professor:
An explicit design goal was to make it run on cheap hardware so students
could afford it. In particular, for years it ran on a regular 4.77 MHZ PC
with no hard disk. You could do everything here including modify and recompile
the system. Just for the record, as of about 1 year ago, there were two
versions, one for the PC (360K diskettes) and one for the 286/386 (1.2M).
The PC version was outselling the 286/386 version by 2 to 1. I don't have
figures, but my guess is that the fraction of the 60 million existing PCs that
are 386/486 machines as opposed to 8088/286/680x0 etc is small. Among students
it is even smaller. Making software free, but only for folks with enough money
to buy first class hardware is an interesting concept.
Of course 5 years from now that will be different, but 5 years from now
everyone will be running free GNU on their 200 MIPS, 64M SPARCstation-5.
>Re 2: your job is being a professor and researcher: That's one hell of a
>good excuse for some of the brain-damages of minix. I can only hope (and
>assume) that Amoeba doesn't suck like minix does.
Amoeba was not designed to run on an 8088 with no hard disk.
>If this was the only criterion for the "goodness" of a kernel, you'd be
>right. What you don't mention is that minix doesn't do the micro-kernel
>thing very well, and has problems with real multitasking (in the
>kernel). If I had made an OS that had problems with a multithreading
>filesystem, I wouldn't be so fast to condemn others: in fact, I'd do my
>damndest to make others forget about the fiasco.
A multithreaded file system is only a performance hack. When there is only
one job active, the normal case on a small PC, it buys you nothing and adds
complexity to the code. On machines fast enough to support multiple users,
you probably have enough buffer cache to insure a hit cache hit rate, in
which case multithreading also buys you nothing. It is only a win when there
are multiple processes actually doing real disk I/O. Whether it is worth
making the system more complicated for this case is at least debatable.
I still maintain the point that designing a monolithic kernel in 1991 is
a fundamental error. Be thankful you are not my student. You would not
get a high grade for such a design :-)
>The fact is that linux is more portable than minix. What? I hear you
>say. It's true - but not in the sense that ast means: I made linux as
>conformant to standards as I knew how (without having any POSIX standard
>in front of me). Porting things to linux is generally /much/ easier
>than porting them to minix.
MINIX was designed before POSIX, and is now being (slowly) POSIXized as
everyone who follows this newsgroup knows. Everyone agrees that user-level
standards are a good idea. As an aside, I congratulate you for being able
to write a POSIX-conformant system without having the POSIX standard in front
of you. I find it difficult enough after studying the standard at great length.
My point is that writing a new operating system that is closely tied to any
particular piece of hardware, especially a weird one like the Intel line,
is basically wrong. An OS itself should be easily portable to new hardware
platforms. When OS/360 was written in assembler for the IBM 360
25 years ago, they probably could be excused. When MS-DOS was written
specifically for the 8088 ten years ago, this was less than brilliant, as
IBM and Microsoft now only too painfully realize. Writing a new OS only for the
386 in 1991 gets you your second 'F' for this term. But if you do real well
on the final exam, you can still pass the course.
Prof. Andrew S. Tanenbaum (ast@cs.vu.nl)
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From: feustel@netcom.COM (David Feustel)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 18:57:28 GMT
Organization: DAFCO - An OS/2 Oasis
ast@cs.vu.nl (Andy Tanenbaum) writes:
>I still maintain the point that designing a monolithic kernel in 1991 is
>a fundamental error. Be thankful you are not my student. You would not
>get a high grade for such a design :-)
That's ok. Einstein got lousy grades in math and physics.
--
David Feustel N9MYI, 1930 Curdes Ave, Fort Wayne, IN 46805. (219)482-9631
feustel@netcom.com
=== NBC News: GE's Advertising And Public Relations Agency ===
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 19:58:50 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
In article <1992Jan30.185728.26477feustel@netcom.COM> feustel@netcom.COM (David
Feustel) writes:
>ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>
>>I still maintain the point that designing a monolithic kernel in 1991 is
>>a fundamental error. Be thankful you are not my student. You would not
>>get a high grade for such a design :-)
>
>That's ok. Einstein got lousy grades in math and physics.
And Dan Quayle got low grades in political science. I think that there
are more Dan Quayles than Einsteins out there... ;-)
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
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From: feustel@netcom.COM (David Feustel)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 23:15:05 GMT
Organization: DAFCO - An OS/2 Oasis
meggin@epas.utoronto.ca (David Megginson) writes:
>In article <1992Jan30.185728.26477feustel@netcom.COM> feustel@netcom.COM (David
Feustel) writes:
>>ast@cs.vu.nl (Andy Tanenbaum) writes:
>>
>>
>>>I still maintain the point that designing a monolithic kernel in 1991 is
>>>a fundamental error. Be thankful you are not my student. You would not
>>>get a high grade for such a design :-)
>>
>>That's ok. Einstein got lousy grades in math and physics.
>And Dan Quayle got low grades in political science. I think that there
>are more Dan Quayles than Einsteins out there... ;-)
But the Existence of Linux suggests that we may have more of an
Einstein than a Quail here.
--
David Feustel N9MYI, 1930 Curdes Ave, Fort Wayne, IN 46805. (219)482-9631
feustel@netcom.com
=== NBC News: GE's Advertising And Public Relations Agency ===
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From: pete@ohm.york.ac.uk (-Pete French.)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 31 Jan 92 09:49:37 GMT
Organization: Electronics Department, University of York, UK
in article <1992Jan30.195850.7023@epas.toronto.edu>, meggin@epas.utoronto.ca
(David Megginson) says:
> Nntp-Posting-Host: epas.utoronto.ca
>
> In article <1992Jan30.185728.26477feustel@netcom.COM> feustel@netcom.COM
(David Feustel) writes:
>>
>>That's ok. Einstein got lousy grades in math and physics.
>
> And Dan Quayle got low grades in political science. I think that there
> are more Dan Quayles than Einsteins out there... ;-)
What a horrible thought !
But on the points about microkernel v monolithic, isnt this partly an
artifact of the language being used ? MINIX may well be designed as a
microkernel system, but in the end you still end up with a large
monolithic chunk of binary data that gets loaded in as "the OS". Isnt it
written as separate programs simply because C does not support the idea
of multiple processes within a single piece of monolithic code. Is there
any real difference between a microkernel written as several pieces of C
and a monolithic kernel written in something like OCCAM ? I would have
thought that in this case the monolithic design would be a better one
than the micorkernel style since with the advantage of inbuilt
language concurrency the kernel could be made even more modular than the
MINIX one is.
Anyone for MINOX :-)
-bat.
--
-Pete French. (the -bat. ) /
Adaptive Systems Engineering /
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From: peter@ferranti.com (peter da silva)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 16:22:32 GMT
Organization: Xenix Support, FICC
In article <1992Jan31.094937.3726@ohm.york.ac.uk> pete@ohm.york.ac.uk (-Pete French.) writes:
> But on the points about microkernel v monolithic, isnt this partly an
> artifact of the language being used ?
I doubt it.
[isn't MINIX]
> written as separate programs simply because C does not support the idea
> of multiple processes within a single piece of monolithic code.
C doesn't support formatted I/O either, but it can be implemented quite
effectively in C. So can concurrent processes. I've done it, in fact.
The resulting code is 90% portable (the 10% being the code that handles
the context switch).
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: kt4@prism.gatech.EDU (Ken Thompson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 23:07:54 GMT
Organization: Georgia Institute of Technology
viewpoint may be largely unrelated to its usefulness. Many if not
most of the software we use is probably obsolete according to the
latest design criteria. Most users could probably care less if the
internals of the operating system they use is obsolete. They are
rightly more interested in its performance and capabilities at the
user level.
I would generally agree that microkernels are probably the wave of
the future. However, it is in my opinion easier to implement a
monolithic kernel. It is also easier for it to turn into a mess in
a hurry as it is modified.
Regards,
Ken
--
Ken Thompson GTRI, Ga. Tech, Atlanta Ga. 30332 Internet:!kt4@prism.gatech.edu
uucp:...!{allegra,amd,hplabs,ut-ngp}!gatech!prism!kt4
"Rowe's Rule: The odds are five to six that the light at the end of the
tunnel is the headlight of an oncoming train." -- Paul Dickson
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From: kevin@taronga.taronga.com (Kevin Brown)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 4 Feb 92 08:08:42 GMT
Organization: University of Houston
In article <47607@hydra.gatech.EDU> kt4@prism.gatech.EDU (Ken Thompson) writes:
>viewpoint may be largely unrelated to its usefulness. Many if not
>most of the software we use is probably obsolete according to the
>latest design criteria. Most users could probably care less if the
>internals of the operating system they use is obsolete. They are
>rightly more interested in its performance and capabilities at the
>user level.
>
>I would generally agree that microkernels are probably the wave of
>the future. However, it is in my opinion easier to implement a
>monolithic kernel. It is also easier for it to turn into a mess in
>a hurry as it is modified.
How difficult is it to structure the source tree of a monolithic kernel
such that most modifications don't have a large negative impact on the
source? What sorts of pitfalls do you run into in this sort of endeavor,
and what suggestions do you have for dealing with them?
I guess what I'm asking is: how difficult is it to organize the source
such that most changes to the kernel remain localized in scope, even
though the kernel itself is monolithic?
I figure you've got years of experience with monolithic kernels :-),
so I'd think you'd have the best shot at answering questions like
these.
>Ken Thompson GTRI, Ga. Tech, Atlanta Ga. 30332 Internet:!kt4@prism.gatech.edu
>uucp:...!{allegra,amd,hplabs,ut-ngp}!gatech!prism!kt4
>"Rowe's Rule: The odds are five to six that the light at the end of the
>tunnel is the headlight of an oncoming train." -- Paul Dickson
Kevin Brown
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From: rburns@finess.Corp.Sun.COM (Randy Burns)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 20:33:07 GMT
Organization: Sun Microsystems, Mt. View, Ca.
NNTP-Posting-Host: finess.corp.sun.com
In article <12615@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <1992Jan29.231426.20469@klaava.Helsinki.FI> torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) writes:
>Of course 5 years from now that will be different, but 5 years from now
>everyone will be running free GNU on their 200 MIPS, 64M SPARCstation-5.
Well, I for one would _love_ to see this happen.
>>The fact is that linux is more portable than minix. What? I hear you
>>say. It's true - but not in the sense that ast means: I made linux as
>>conformant to standards as I knew how (without having any POSIX standard
>>in front of me). Porting things to linux is generally /much/ easier
>>than porting them to minix.
.........
>My point is that writing a new operating system that is closely tied to any
>particular piece of hardware, especially a weird one like the Intel line,
>is basically wrong.
First off, the parts of Linux tuned most finely to the 80x86 are the Kernel
and the devices. My own sense is that even if Linux is simply a stopgap
measure to let us all run GNU software, it is still worthwhile to have a
a finely tuned kernel for the most numerous architecture presently in
existance.
> An OS itself should be easily portable to new hardware
>platforms.
Well, the only part of Linux that isn't portable is the kernel and drivers.
Compare to the compilers, utilities, windowing system etc. this is really
a small part of the effort. Since Linux has a large degree of call
compatibility with portable OS's I wouldn't complain. I'm personally
very grateful to have an OS that makes it more likely that some of us will
be able to take advantage of the software that has come out of Berkeley,
FSF, CMU etc. It may well be that in 2-3 years when ultra cheap BSD
variants and Hurd proliferate, that Linux will be obsolete. Still, right
now Linux greatly reduces the cost of using tools like gcc, bison, bash
which are useful in the development of such an OS.
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From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 31 Jan 92 10:33:23 GMT
Organization: University of Helsinki
In article <12615@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>The limitations of MINIX relate at least partly to my being a professor:
>An explicit design goal was to make it run on cheap hardware so students
>could afford it.
All right: a real technical point, and one that made some of my comments
inexcusable. But at the same time you shoot yourself in the foot a bit:
now you admit that some of the errors of minix were that it was too
portable: including machines that weren't really designed to run unix.
That assumption lead to the fact that minix now cannot easily be
extended to have things like paging, even for machines that would
support it. Yes, minix is portable, but you can rewrite that as
"doesn't use any features", and still be right.
>A multithreaded file system is only a performance hack.
Not true. It's a performance hack /on a microkernel/, but it's an
automatic feature when you write a monolithic kernel - one area where
microkernels don't work too well (as I pointed out in my personal mail
to ast). When writing a unix the "obsolete" way, you automatically get
a multithreaded kernel: every process does it's own job, and you don't
have to make ugly things like message queues to make it work
efficiently.
Besides, there are people who would consider "only a performance hack"
vital: unless you have a cray-3, I'd guess everybody gets tired of
waiting on the computer all the time. I know I did with minix (and yes,
I do with linux too, but it's /much/ better).
>I still maintain the point that designing a monolithic kernel in 1991 is
>a fundamental error. Be thankful you are not my student. You would not
>get a high grade for such a design :-)
Well, I probably won't get too good grades even without you: I had an
argument (completely unrelated - not even pertaining to OS's) with the
person here at the university that teaches OS design. I wonder when
I'll learn :)
>My point is that writing a new operating system that is closely tied to any
>particular piece of hardware, especially a weird one like the Intel line,
>is basically wrong.
But /my/ point is that the operating system /isn't/ tied to any
processor line: UNIX runs on most real processors in existence. Yes,
the /implementation/ is hardware-specific, but there's a HUGE
difference. You mention OS/360 and MS-DOG as examples of bad designs
as they were hardware-dependent, and I agree. But there's a big
difference between these and linux: linux API is portable (not due to my
clever design, but due to the fact that I decided to go for a fairly-
well-thought-out and tested OS: unix.)
If you write programs for linux today, you shouldn't have too many
surprises when you just recompile them for Hurd in the 21st century. As
has been noted (not only by me), the linux kernel is a miniscule part of
a complete system: Full sources for linux currently runs to about 200kB
compressed - full sources to a somewhat complete developement system is
at least 10MB compressed (and easily much, much more). And all of that
source is portable, except for this tiny kernel that you can (provably:
I did it) re-write totally from scratch in less than a year without
having /any/ prior knowledge.
In fact the /whole/ linux kernel is much smaller than the 386-dependent
things in mach: i386.tar.Z for the current version of mach is well over
800kB compressed (823391 bytes according to nic.funet.fi). Admittedly,
mach is "somewhat" bigger and has more features, but that should still
tell you something.
Linus
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Newsgroups: comp.os.minix
From: kevin@nuchat.sccsi.com (Kevin Brown)
Subject: Re: LINUX is obsolete
Organization: Where???
Date: Fri, 31 Jan 1992 07:43:47 GMT
Sorry, but I just can't resist this thread...:-)
In article <12615@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <1992Jan29.231426.20469@klaava.Helsinki.FI> torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) writes:
>>You use this [being a professor] as an excuse for the limitations of minix?
>The limitations of MINIX relate at least partly to my being a professor:
>An explicit design goal was to make it run on cheap hardware so students
>could afford it. In particular, for years it ran on a regular 4.77 MHZ PC
>with no hard disk.
And an explicit design goal of Linux was to take advantage of the special
features of the 386 architecture. So what exactly is your point? Different
design goals get you different designs. You ought to know that.
>You could do everything here including modify and recompile
>the system. Just for the record, as of about 1 year ago, there were two
>versions, one for the PC (360K diskettes) and one for the 286/386 (1.2M).
>The PC version was outselling the 286/386 version by 2 to 1. I don't have
>figures, but my guess is that the fraction of the 60 million existing PCs that
>are 386/486 machines as opposed to 8088/286/680x0 etc is small. Among students
>it is even smaller.
I find it very interesting that you claim here that Minix was designed
primarily for cheap hardware (in particular, the IBM PC/XT with no hard
disk) and yet elsewhere have also mentioned the virtues of being portable
across hardware platforms. Well, if you insist on designing the thing
with the lowest common denominator as your basis, that's fine, but of
course the end result will be less than pretty unless designed *very*
carefully.
>Making software free, but only for folks with enough money
>to buy first class hardware is an interesting concept.
Except that Linux was designed more for the purposes of the designer than
anything else. If I were writing an OS, I'd design it to suit myself, too.
It's just that Linus was nice enough to share his code with the rest of us.
>Of course 5 years from now that will be different, but 5 years from now
>everyone will be running free GNU on their 200 MIPS, 64M SPARCstation-5.
Maybe. But by then, the 386/486 will probably be where the PC is now:
everyone will have one and they'll be dirt cheap. The timing will be
about right. In which case Linux will fit right in, wouldn't you say?
>>Re 2: your job is being a professor and researcher: That's one hell of a
>>good excuse for some of the brain-damages of minix. I can only hope (and
>>assume) that Amoeba doesn't suck like minix does.
>Amoeba was not designed to run on an 8088 with no hard disk.
Here's a question for you: as a general rule, when you go to design an
operating system, do you design it for specific capabilities and then run
it on whatever hardware will do the job, or do you design it with the
hardware as a target and fit the capabilities to the hardware? With respect
to Minix, it seems you did the latter, but I don't know whether or not you
did that with Amoeba.
>>If this was the only criterion for the "goodness" of a kernel, you'd be
>>right. What you don't mention is that minix doesn't do the micro-kernel
>>thing very well, and has problems with real multitasking (in the
>>kernel). If I had made an OS that had problems with a multithreading
>>filesystem, I wouldn't be so fast to condemn others: in fact, I'd do my
>>damndest to make others forget about the fiasco.
>A multithreaded file system is only a performance hack.
Bull. A multithreaded file system has a completely different design than
a single-threaded file system and has different design criteria than a
single-threaded file system.
>When there is only one job active, the normal case on a small PC, it buys
>you nothing and adds complexity to the code.
If there is only going to be one job active anyway then *why bother with
multitasking at all*????
If you're going to implement multitasking, then don't do a halfway job
of it. On the other hand, if you're going to assume that there will be
only one job active anyway, then don't bother with multitasking (after
all, it *does* complicate things :-).
>On machines fast enough to
>support multiple users, you probably have enough buffer cache to insure a
>hit cache hit rate, in which case multithreading also buys you nothing.
Maybe. Multiple users means multiple things being done simultaneously. I
wouldn't bet on the buffer cache buying you so much that multithreading
makes no difference. It's one thing if the users are doing something
simple, like editing a file. It's another thing if they're compiling,
reading news, or other things that touch lots of different files.
>It is only a win when there are multiple processes actually doing real disk
>I/O.
Which happens a *lot* when you're running multiple users. Or when you're
a machine hooked up to the net and handling news traffic.
>Whether it is worth making the system more complicated for this case is
>at least debatable.
Oh, come on. How tough is it to implement a multi-threaded file system?
All you need is a decent *buffered* (preferably infinitely so)
message-passing system and a way to save your current state when you send
out a request to the device driver(s) to perform some work (and obviously
some way to restore that state). Minix has the second via the setjmp()/
longjmp() mechanism, but lacks the former in a serious way.
>I still maintain the point that designing a monolithic kernel in 1991 is
>a fundamental error.
Not if you're trying to implement the system call semantics of Unix in a
reasonably simple and elegant way.
>Be thankful you are not my student. You would not
>get a high grade for such a design :-)
Why not? What's this big thing against monolithic kernels? There are
certain classes of problems for which a monolithic kernel is a more
appropriate design than a microkernel architecture. I think implementing
Unix semantics with a minimum of fuss is one such problem.
Unless you can suggest an elegant way to terminate a system call upon
receipt of a signal from within a microkernel OS?
>>The fact is that linux is more portable than minix. What? I hear you
>>say. It's true - but not in the sense that ast means: I made linux as
>>conformant to standards as I knew how (without having any POSIX standard
>>in front of me). Porting things to linux is generally /much/ easier
>>than porting them to minix.
>MINIX was designed before POSIX, and is now being (slowly) POSIXized as
>everyone who follows this newsgroup knows. Everyone agrees that user-level
>standards are a good idea. As an aside, I congratulate you for being able
>to write a POSIX-conformant system without having the POSIX standard in front
>of you. I find it difficult enough after studying the standard at great length.
>
>My point is that writing a new operating system that is closely tied to any
>particular piece of hardware, especially a weird one like the Intel line,
>is basically wrong.
Weird as the Intel line may be, it's *the* most popular line, by several
times. So it's not like it's *that* big a loss. And Intel hardware is
at least relatively cheap to come by, regardless of what your students
might tell you (why do you think they all own PCs?)...
>An OS itself should be easily portable to new hardware
>platforms.
As long as you don't sacrifice too much in the way of performance or
architectural elegance in order to gain this. Unfortunately, that's
*exactly* what happened with Minix: in attempting to implement it on
hardware of the lowest caliber, you ended up having to make design
decisions with respect to the architecture and implementation that have
made vintage Minix unusable as anything more than a personal toy operating
system. For example: why didn't you implement a system call server as
a layer between the file system and user programs? My guess: you didn't
have enough memory on the target machine to do it.
Put another way: you hit your original goal right on target, and are to
be applauded for that. But in doing so, you missed a lot of other
targets that wouldn't have been hard to hit as well, with some
consideration of them. I think. But I wasn't there when you were making
the decisions, so it's real hard for me to say for sure. I'm speaking
from hindsight, but you had the tough problem of figuring out what to do
without such benefit.
Now, *modified* Minix is usable. Add a bigger buffer cache. Modify it
so that it can take advantage of 386 protected mode. Fix the tty driver
so that it will give you multiple consoles. Fix the rs232 driver to deal
with DCD/DTR and do the right thing when carrier goes away. Fix the pipes
so that read and write requests don't fail just because they happen to be
bigger than the size of a physical pipe. Add shared text segments so you
maximize the use of your RAM. Fix the scheduler so that it deals with
character I/O bound processes in a reasonable way.
>When OS/360 was written in assembler for the IBM 360
>25 years ago, they probably could be excused. When MS-DOS was written
>specifically for the 8088 ten years ago, this was less than brilliant, as
>IBM and Microsoft now only too painfully realize.
Yeah, right. Just what hardware do you think they'd like to port DOS to,
anyway? I can't think of any. I don't think IBM or Microsoft are
regretting *that* particular aspect of DOS. Rather, they're probably
regretting the fact that it was written for the address space provided
by the 8088.
MS-DOS isn't less than brilliant because it was written for one machine
architecture. It's less than brilliant because it doesn't do anything
well, *regardless* of its portability or lack thereof.
>Writing a new OS only for the
>386 in 1991 gets you your second 'F' for this term. But if you do real well
>on the final exam, you can still pass the course.
He made his code freely redistributable. *You* didn't even do that. Just
for that move alone, he scores points in my book. Of course, the
distribution technology available to him is much better than what was
available when you did Minix, so it's hard to fault you for that...
But I must admit, Minix is still one hell of a bargain, and I would never
hesitate to recommend it to anyone who wants to learn something about Unix
and operating systems in general. As a working operating system (i.e.,
one intended for a multi-user environment), however, I'd hesitate to
recommend it, except that there really aren't any good alternatives
(except Linux, of course, at least tentatively. I can't say for sure,
since I haven't checked out Linux yet), since it doesn't have the performance
capabilities that a working operating system needs.
>Prof. Andrew S. Tanenbaum (ast@cs.vu.nl)
Kevin Brown
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Newsgroups: comp.os.minix
From: kevin@taronga.taronga.com (Kevin Brown)
Subject: Re: LINUX is obsolete
Organization: Sorely lacking.
Date: Mon, 3 Feb 1992 05:12:58 GMT
It has been brought to my attention that my last posting was exceedingly
harsh. Having reread it, I'm inclined to agree.
Dr. Tanenbaum claims that the microkernel architecture is the way to go.
He has a great deal more experience with operating systems than I have.
It's an understatement that it's likely that there's some substance to
his statement. :-)
Many of the things I said in my previous posting were more a result of my
philosophical viewpoint on operating systems and programming in general
than experience. And the particular viewpoint I hold that's relevent to
the discussion says that the method of implementation chosen depends on
the design goals, and that there is no "wrong" or "right" way to do things
that is independent of such goals. Thus, my statement that a monolithic
kernel follows from some design goals, e.g. ease of implementation of the
semantics of the Unix API. In particular, the ease of implementing things
like signal handling, premature system call termination, etc. At least,
that's the conclusion I come to when I think about the problem.
My experience with Minix says that there are a number of things that should
not go in a user process, things that are better left in the kernel. Things
like memory allocation (which requires global knowledge of the hardware,
something that a user process should, IMHO, not have) and signal handling
(which requires building stack frames).
÷³So from my point of view, the architecture of Minix is not ideal. While
it may win in that it's a "microkernel" architecture, the division of
functionality is not entirely to my liking. As is undoubtedly plainly
obvious by now. :-)
Despite that, Minix is quite usable in many ways as a personal operating
system, i.e. one where there is usually only one person logged into the
system. If I gave the impression that I thought it was unusable in general,
then I apologize for that.
However, as a *multiuser* operating system, þòi.e. an operating system designed
to efficiently meet the needs of multiple users simultaneously while also
performing batch operations, Minix is lacking, as far as I'm concerned.
The main reason, of course, is the single-threaded file system (hereafter,
STFS). Now, Dr. Tanenbaum may feel that a multi-threaded file system
(hereafter, MTFS) is merely a performance hack. Perhaps he's right.
Perhaps the architecture of a MTFS is sufficiently similar to that of a
STFS that his assessment is correct. My vision of a MTFS may differ
significantly from his, and this would explain why he and I seem to have
a difference of opinion on this matter. Regardless of whether or not a
MTFS is a "performance hack", for a *multiuser* operating system, I think
there are a lot of good arguments that say that a MTFS is a *necessary*
"performance hack". Provided, of course, that one does not have infinite
buffer cache resources. :-)
There are other things I feel Minix lacks as well. The ability to allocate
memory in the kernel is one (such an ability would allow any user process,
e.g. device drivers and the file system, to allocate memory dynamically.
This is useful for doing things like resizing the buffer cache on the fly,
etc. The ability to pass arbitrarily sized messages, optionally via shared
memory, is another (such an ability might be limited by constraints like
page size and such).
However much Minix may be lacking from my standpoint, it is nevertheless
a very useful and welcome enhancement to my system. In spite of the
impression that I may have given everyone in my last posting, there will
always be a soft spot in my heart for it, if only because it's the first
decent operating system I've had on my system that I've had source to.
I don't have to tell you people how incredibly useful it is to have source.
You already know.
It is very important to me to have source code to the things I run. It
bothers me a great deal to run things that I don't have source to. Even
the C compiler. And the less expensive the source is, the better. This
is why Dr. Tanenbaum's statements about Linux touched a raw nerve with me:
Linux comes with source *and* it's free. And it's available right now.
Someone, either here on this newsgroup or over on alt.os.linux, made a
very valid observation: the cost of a 16 MHz 386SX system is about $140
more than a comparably equipped (in terms of RAM size, display technology,
hard drive space, etc.) 8088 system. Minix is $169. In economic terms,
Linux wins if you have to buy Minix.
Where Minix wins (or is at least even :-) is when you can get it for free
via the educational distribution clause of the license agreement. However,
Minix will run even better on a 16 MHz 386SX than on an 8088. If I were
a student, I'd get the 386SX unless I simply didn't have a choice. Then
I'd get whichever operating system I could get for the least cost. If I
could get both for free, then I'd get both. :-)
Given the reasons Linus wrote Linux, I think it's hard for anyone to fault
him for writing it the way he did. And he was extremely nice in making
his code freely available to the rest of the world. It's not something he
had to do. In my book, that makes him almost beyond reproach.
Dr. Tanenbaum didn't make Minix free. His goals were different. Minix
is a teaching aid above all else (unless Dr. Tanenbaum has changed his
views about Minix :-). That means that he must be concerned with the
most efficient way to get Minix to the student population. At the time
Minix was released, Prentice-Hall was a good solution, and has been for
some time. However, I must wonder whether or not this is still the case.
Dr. Tanenbaum: do you still feel that free distribution of Minix via the
net is not the best way to distribute Minix?
Which wins? Minix or Linux? Depends on how you measure them...
Kevin Brown
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From: kaufman@eecs.nwu.edu (Michael L. Kaufman)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 22:27:48 GMT
Organization: EECS Department, Northwestern University
I tried to send these two posts from work, but I think they got eaten. If you
have seen them already, sorry.
-------------------------------------------------------------------------------
Andy Tanenbaum writes an interesting article (also interesting was finding out
that he actually reads this group) but I think he is missing an important
point.
He Wrote:
>As most of you know, for me MINIX is a hobby, ...
Which is also probably true of most, if not all, of the people who are involved
in Linux. We are not developing a system to take over the OS market, we are
just having a good time.
> What is going to happen
> is that they will gradually take over from the 80x86 line. They will
> run old MS-DOS programs by interpreting the 80386 in software.
Well when this happens, if I still want to play with Linux, I can just run it
on my 386 simulator.
> MINIX was designed to be reasonably portable, and has been ported from the
> Intel line to the 680x0 (Atari, Amiga, Macintosh), SPARC, and NS32016.
> LINUX is tied fairly closely to the 80x86. Not the way to go.
That's fine for the people who have those machines, but it wasn't a free
lunch. That portibility was gained at the cost of some performance and some
features on the 386. Before you decide that LINUX is not the way to go, you
should think about what it is going to be used for. I am going to use it for
running memory and computation intensive graphics programs on my 486. For me,
speed and memory were more important then future state-of-the-artness and
portability.
>But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
I don't know of any free microkernel-based, portable OSes. GNU is still
vaporware, and likely to remain that way for the forseeable future. Do
you actually have one to recomend, or are you just toying with me? ;-)
------------------------------------------------------------------------------
In article <12615@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>My point is that writing a new operating system that is closely tied to any
>particular piece of hardware, especially a weird one like the Intel line,
>is basically wrong. An OS itself should be easily portable to new hardware
>platforms.
I think I see where I disagree with you now. You are looking at OS design
as an end in itself. Minix is good because it is portable/Micro-Kernal/etc.
Linux is not good because it is monolithic/tightly tied to Intel/etc. That
is not a strange attitude for someone in the acedemic world, but it is not
something you should expect to be universally shared. Linux is not being written
as a teaching tool, or as an abstract exercise. It is being written to allow
people to run GNU-type software _today_. The fact that it may not be in use
in five years is less important then the fact that today (well, by April
probably) I can run all sorts of software on it that I want to run. You keep
saying that Minix is better, but if it will not run the software that I want
to run, it really isn't that good (for me) at all.
> When OS/360 was written in assembler for the IBM 360
>25 years ago, they probably could be excused. When MS-DOS was written
>specifically for the 8088 ten years ago, this was less than brilliant, as
>IBM and Microsoft now only too painfully realize.
Same point. MSoft did not come out with Dos to "explore the frontiers of os
research". They did it to make a buck. And considering the fact that MS-DOS
probably still outsells everyone else put together, I don't think that you
say that they have failed _in their goals_. Not that MS-Dos is the best OS
in terms of anything else, only that it has served their needs.
Michael
--
Michael Kaufman | I've seen things you people wouldn't believe. Attack ships on
kaufman | fire off the shoulder of Orion. I watched C-beams glitter in
@eecs.nwu.edu | the dark near the Tannhauser gate. All those moments will be
| lost in time - like tears in rain. Time to die. Roy Batty
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From: entropy@wintermute.WPI.EDU (Lawrence C. Foard)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 6 Feb 92 09:22:40 GMT
Organization: Worcester Polytechnic Institute
Nntp-Posting-Host: wintermute.wpi.edu
In article <1992Feb3.051258.4153@menudo.uh.edu> kevin@taronga.taronga.com (Kevin Brown) writes:
>Dr. Tanenbaum claims that the microkernel architecture is the way to go.
>He has a great deal more experience with operating systems than I have.
>It's an understatement that it's likely that there's some substance to
>his statement. :-)
I tend to prefer seeing for myself rather than accepting "expert" opinion.
Microkernels are nice asthetically, but there are times when practical issues
must also be considered :)
>w3So from my point of view, the architecture of Minix is not ideal. While
>it may win in that it's a "microkernel" architecture, the division of
>functionality is not entirely to my liking. As is undoubtedly plainly
>obvious by now. :-)
I've been told by people who have used both that Linux is significantly
faster. There are certainly several factors involved (certainly using 32 bits
helps alot), but the multithreading also makes for much lower overhead.
>However, as a *multiuser* operating system, ~ri.e. an operating system designed
>to efficiently meet the needs of multiple users simultaneously while also
>performing batch operations, Minix is lacking, as far as I'm concerned.
>The main reason, of course, is the single-threaded file system (hereafter,
>STFS). Now, Dr. Tanenbaum may feel that a multi-threaded file system
>(hereafter, MTFS) is merely a performance hack.
I think this is a very valid problem. There are two ways a single threaded FS
could work and both have substantial problems. If the FS blocks while waiting
for I/O it would be completely unusable for "real" work. Imagine several users
accessing a database, if the FS blocks for I/O they will have to wait
eventhough the data they are looking for is already in the cache. If it is
designed to be non blocking then it is even more complicated than a
multithreaded FS and will have more overhead. I hope it is atleast the second
>However much Minix may be lacking from my standpoint, it is nevertheless
>a very useful and welcome enhancement to my system. In spite of the
>impression that I may have given everyone in my last posting, there will
>always be a soft spot in my heart for it, if only because it's the first
>decent operating system I've had on my system that I've had source to.
>I don't have to tell you people how incredibly useful it is to have source.
>You already know.
I will agree here, Minix is infinitly better than Messy-Loss :)
>Given the reasons Linus wrote Linux, I think it's hard for anyone to fault
>him for writing it the way he did. And he was extremely nice in making
>his code freely available to the rest of the world. It's not something he
>had to do. In my book, that makes him almost beyond reproach.
I think more effort has been put into making practical use of Linux possible.
An educational OS is nice, but there is a world outside of colleges that
is suffering from the lack of cheap and useful OS's, I've been stuck doing
most consulting work in Messy Loss because customers don't want to fork out
$1000 for UNIX.
>Dr. Tanenbaum didn't make Minix free. His goals were different. Minix
>is a teaching aid above all else (unless Dr. Tanenbaum has changed his
>views about Minix :-). That means that he must be concerned with the
>most efficient way to get Minix to the student population. At the time
>Minix was released, Prentice-Hall was a good solution, and has been for
>some time. However, I must wonder whether or not this is still the case.
>Dr. Tanenbaum: do you still feel that free distribution of Minix via the
>net is not the best way to distribute Minix?
I would guess that Prentice-Hall would have some objections :)
--
Disclaimer: Opinions are based on logic rather than biblical "fact". ------
This is your friendly | First they came for the drug users, I said \ /
neighborhood signature virus | nothing, then they came for hackers, \ /
please add me to your signature! | I said nothing... STOP W.O.D. \/
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From: kevin@taronga.com (Kevin Brown)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 9 Feb 92 09:02:24 GMT
Organization: What's that?
In article <1992Feb6.092240.16377@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>In article <1992Feb3.051258.4153@menudo.uh.edu> kevin@taronga.taronga.com (Kevin Brown) writes:
>>Dr. Tanenbaum claims that the microkernel architecture is the way to go.
>>He has a great deal more experience with operating systems than I have.
>>It's an understatement that it's likely that there's some substance to
>>his statement. :-)
>
>I tend to prefer seeing for myself rather than accepting "expert" opinion.
>Microkernels are nice asthetically, but there are times when practical issues
>must also be considered :)
I agree. This is why I qualified my statement the way I did. :-)
Having seen both monolithic and microkernel architectures running, though,
I tend to agree that microkernels are generally the way to go, all other
things being equal.
But as you say, all things are not always equal. That's when it becomes
a judgement call. Which is better? Depends on what you're trying to do.
>I've been told by people who have used both that Linux is significantly
>faster. There are certainly several factors involved (certainly using 32 bits
>helps alot), but the multithreading also makes for much lower overhead.
Yup. I think that if Minix were arranged so that it had message queueing
and a true multithreaded filesystem, it might be comparable to a monolithic
kernel in terms of speed. It's hard for me to say, though. I haven't
played around much with multithreaded filesystems, so I don't know how
hard it is to make them work efficiently. I'd think, though, that it would
depend enormously on how efficient your device drivers were, and how much
data copying you'd have to do (ideally, you'd pass references to the data
buffers around and do your actual data transfers directly to the user's
buffer).
>>However, as a *multiuser* operating system, i.e. an operating system designed
>>to efficiently meet the needs of multiple users simultaneously while also
>>performing batch operations, Minix is lacking, as far as I'm concerned.
>>The main reason, of course, is the single-threaded file system (hereafter,
>>STFS). Now, Dr. Tanenbaum may feel that a multi-threaded file system
>>(hereafter, MTFS) is merely a performance hack.
>
>I think this is a very valid problem. There are two ways a single threaded FS
>could work and both have substantial problems. If the FS blocks while waiting
>for I/O it would be completely unusable for "real" work. Imagine several users
>accessing a database, if the FS blocks for I/O they will have to wait
>eventhough the data they are looking for is already in the cache. If it is
>designed to be non blocking then it is even more complicated than a
>multithreaded FS and will have more overhead. I hope it is atleast the second
I haven't gone deeply into the source code of the Minix file system, but
the impression I get from my perusing of it is that it blocks on disk I/O
but not on terminal I/O, the idea being that disk I/O requests will almost
always be satisfied relatively soon after they are made, whereas terminal
I/O requests can take an indefinite amount of time to satisfy.
But it seems to me that if you're going to implement the mechanism to handle
I/O where the file system doesn't block waiting for it, why not use that
mechanism universally???
>>However much Minix may be lacking from my standpoint, it is nevertheless
>>a very useful and welcome enhancement to my system. In spite of the
>>impression that I may have given everyone in my last posting, there will
>>always be a soft spot in my heart for it, if only because it's the first
>>decent operating system I've had on my system that I've had source to.
>>I don't have to tell you people how incredibly useful it is to have source.
>>You already know.
>
>I will agree here, Minix is infinitly better than Messy-Loss :)
Which is why I try to avoid using MS-DOS whenever possible. I'll bet a
lot of us Minixers do the same. :-)
>>Given the reasons Linus wrote Linux, I think it's hard for anyone to fault
>>him for writing it the way he did. And he was extremely nice in making
>>his code freely available to the rest of the world. It's not something he
>>had to do. In my book, that makes him almost beyond reproach.
>
>I think more effort has been put into making practical use of Linux possible.
>An educational OS is nice, but there is a world outside of colleges that
>is suffering from the lack of cheap and useful OS's, I've been stuck doing
>most consulting work in Messy Loss because customers don't want to fork out
>$1000 for UNIX.
Even students can make good use of something like Linux. I have 8 megabytes
of RAM on my machine, and 410 meg of harddrive space. Yet I can barely
run SBProlog on my system, even though my system is considerably more macho
than most. If I had demand paging on my system, this wouldn't be a problem,
but the only patches I have for demand paging seem not to work very well.
Once Linux becomes more stable (and gets support for Seagate ST-02 SCSI),
I'll snag the sources and check it out. Since I already own Minix, I can
legally transport *everything* over to it, and since both share the same
filesystem layout, I can do the transporting with a minimum of hassle.
>>Dr. Tanenbaum didn't make Minix free. His goals were different. Minix
>>is a teaching aid above all else (unless Dr. Tanenbaum has changed his
>>views about Minix :-). That means that he must be concerned with the
>>most efficient way to get Minix to the student population. At the time
>>Minix was released, Prentice-Hall was a good solution, and has been for
>>some time. However, I must wonder whether or not this is still the case.
>>Dr. Tanenbaum: do you still feel that free distribution of Minix via the
>>net is not the best way to distribute Minix?
>
>I would guess that Prentice-Hall would have some objections :)
No doubt. :-(
--
Kevin Brown Disclaimer: huh?
kevin@taronga.com kevin@nuchat.sccsi.com
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From: julien@incal.inria.fr (Julien Maisonneuve)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 17:10:14 GMT
I would like to second Kevin brown in most of his remarks.
I'll add a few user points :
- When ast states that FS multithreading is useless, it reminds me of the many
times I tried to let a job run in the background (like when reading an archive on
a floppy), it is just unusable, the & shell operator could even have been left
out.
- Most interesting utilities are not even compilable under Minix because of the
ATK compiler's incredible limits. Those were hardly understandable on a basic PC,
but become absurd on a 386. Every stupid DOS compiler has a large model (more
expensive, OK). I hate the 13 bit compress !
- The lack of Virtual Memory support prevents people studying this area to
experiment, and prevents users to use large programs. The strange design of the
MM also makes it hard to modify.
The problem is that even doing exploratory work under minix is painful.
If you want to get any work done (or even fun), even DOS is becoming a better
alternative (with things like DJ GPP).
In its basic form, it is really no more than OS course example, a good
toy, but a toy. Obtaining and applying patches is a pain, and precludes further
upgrades.
Too bad when not so much is missing to make it really good.
Thanks for the work andy, but Linux didn't deserve your answer.
For the common people, it does many things better than Minix.
Julien Maisonneuve.
This is not a flame, just my experience.
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From: richard@aiai.ed.ac.uk (Richard Tobin)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 4 Feb 92 14:46:49 GMT
Reply-To: richard@aiai.UUCP (Richard Tobin)
Organization: AIAI, University of Edinburgh, Scotland
In article <12615@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>A multithreaded file system is only a performance hack. When there is only
>one job active, the normal case on a small PC, it buys you nothing
I find the single-threaded file system a serious pain when using
Minix. I often want to do something else while reading files from the
(excruciatingly slow) floppy disk. I rather like to play rogue while
waiting for large C or Lisp compilations. I look to look at files in
one editor buffer while compiling in another.
(The problem would be somewhat less if the file system stuck to
serving files and didn't interact with terminal i/o.)
Of course, in basic Minix with no virtual consoles and no chance of
running emacs, this isn't much of a problem. But to most people
that's a failure, not an advantage. It just isn't the case that on
single-user machines there's no use for more than one active process;
the idea only has any plausibility because so many people are used to
poor machines with poor operating systems.
As to portability, Minix only wins because of its limited ambitions.
If you wanted a full-featured Unix with paging, job-control, a window
system and so on, would it be quicker to start from basic Minix and
add the features, or to start from Linux and fix the 386-specific
bits? I don't think it's fair to criticise Linux when its aims are so
different from Minix's. If you want a system for pedagogical use,
Minix is the answer. But if what you want is an environment as much
like (say) a Sun as possible on your home computer, it has some
deficiencies.
-- Richard
--
Richard Tobin,
AI Applications Institute, R.Tobin@ed.ac.uk
Edinburgh University.
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 5 Feb 92 14:48:48 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <6121@skye.ed.ac.uk> richard@aiai.UUCP (Richard Tobin) writes:
>If you wanted a full-featured Unix with paging, job-control, a window
>system and so on, would it be quicker to start from basic Minix and
>add the features, or to start from Linux and fix the 386-specific
>bits?
Another option that seems to be totally forgotten here is buy UNIX or a
clone. If you just want to USE the system, instead of hacking on its
internals, you don't need source code. Coherent is only $99, and there
are various true UNIX systems with more features for more money. For the
true hacker, not having source code is fatal, but for people who just
want a UNIX system, there are many alternatives (albeit not free).
Andy Tanenbaum (ast@cs.vul.nl)
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From: linville@garfield.catt.ncsu.edu (John W. Linville)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Summary: Small model compiler limits Coherent as an alternative
Date: 5 Feb 92 17:56:35 GMT
Organization: NCSU CATT Prog
In article <12696@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <6121@skye.ed.ac.uk> richard@aiai.UUCP (Richard Tobin) writes:
>>If you wanted a full-featured Unix with paging, job-control, a window
>>system and so on, would it be quicker to start from basic Minix and
>>add the features, or to start from Linux and fix the 386-specific
>>bits?
>
>Another option that seems to be totally forgotten here is buy UNIX or a
>clone. If you just want to USE the system, instead of hacking on its
>internals, you don't need source code. Coherent is only $99, and there
>are various true UNIX systems with more features for more money. For the
>true hacker, not having source code is fatal, but for people who just
>want a UNIX system, there are many alternatives (albeit not free).
>
>Andy Tanenbaum (ast@cs.vul.nl)
Coherent is limited by a compiler that only supports the small memory model,
making it just as difficult (perhaps more in some instances) to port 'standard'
Unix programs to Coherent as it can be under Minix. Also, Coherent is not
portable (or at least, to the best of my knowledge, has not been ported), so
this advocacy contradicts one of your arguments against Linux.
Since a true Unix system often costs as much as the machine it runs on (even
more since many Unix providers un-bundle networking and development packages),
buying a true Unix system is more than beyond the budget of many people.
John W. Linville
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From: jerry@connection.prospect.com (Jerry Shekhel)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 6 Feb 92 21:28:05 GMT
Organization: Polygen Corporation, Waltham, MA
linville@garfield.catt.ncsu.edu (John W. Linville) writes:
>
>Since a true Unix system often costs as much as the machine it runs on (even
>more since many Unix providers un-bundle networking and development packages),
>buying a true Unix system is more than beyond the budget of many people.
>
For those who may be interested, MST sells System V Release 4.0.3 for the
386/486 for $399 including development system, $499 if you need networking.
X11R5 binaries may be obtained via FTP (networking is not required for X11R5).
I have just such a setup, and it works great. MST's version of UNIX doesn't
have too much in the way of bug fixes relative to the AT&T code, but the
only thing I've really had problems with was a couple of bugs in csh. Now
that I have tcsh working (built without so much as a warning!) I'll never go
back :-)
Micro Station Technology
1140 Kentwood Avenue
Cupertine, CA 95014
Tel: 408-253-3898
Fax: 408-253-7853
I am not affiliated with MST except as a customer.
>
>John W. Linville
>
--
+-------------------+----------------------+---------------------------------+
| JERRY J. SHEKHEL | POLYGEN CORPORATION | When I was young, I had to walk |
| Drummers do it... | Waltham, MA USA | to school and back every day -- |
| ... In rhythm! | (617) 890-2175 | 20 miles, uphill both ways. |
+-------------------+----------------------+---------------------------------+
| ...! [ princeton mit-eddie bu sunne ] !polygen!jerry |
| jerry@polygen.com |
+----------------------------------------------------------------------------+
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 5 Feb 92 20:50:55 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
In article <12696@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>Another option that seems to be totally forgotten here is buy UNIX or a
>clone. If you just want to USE the system, instead of hacking on its
>internals, you don't need source code. Coherent is only $99, and there
>are various true UNIX systems with more features for more money. For the
>true hacker, not having source code is fatal, but for people who just
>want a UNIX system, there are many alternatives (albeit not free).
What Unix's _are_ available for a simple, M68000-based ST, with _or_
without source? These are the only options I know of:
1) OS 9.
2) The Beckmeyer MT C-Shell.
3) MiNT.
4) Minix.
I have used all of these except for OS 9, and Minix is clearly the
closest thing to Unix that I can run (though it is easier to port BSD
programs to MiNT using the MiNT gcc library). I could shell out CAN
$3000 for a TT, but then I may as well buy a 386 box anyway. Besides,
I _like_ having the source. The extra advantage of Minix is that the
user base is a lot wider than the ST market, so I can get decent
system enhancements from Amiga, Mac, Sparc, XT, AT, '386 and '486
users as well as from fellow ST owners.
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
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From: ajt@doc.ic.ac.uk (Tony Travis)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 6 Feb 92 02:17:13 GMT
Organization: Department of Computing, Imperial College, University of London, UK.
ast@cs.vu.nl (Andy Tanenbaum) writes:
> Another option that seems to be totally forgotten here is buy UNIX or a
> clone. If you just want to USE the system, instead of hacking on its
> internals, you don't need source code. Coherent is only $99, and there
> are various true UNIX systems with more features for more money. For the
> true hacker, not having source code is fatal, but for people who just
> want a UNIX system, there are many alternatives (albeit not free).
Andy, I have followed the development of Minix since the first messages
were posted to this group and I am now running 1.5.10 with Bruce
Evans's patches for the 386.
I 'just' want a Unix on my PC and I am not interested in hacking on its
internals, but I *do* want the source code!
An important principle underlying the success and popularity of Unix is
the philosophy of building on the work of others.
This philosophy relies upon the availability of the source code in
order that it can be examined, modified and re-used in new software.
Many years ago, I was in the happy position of being an AT&T Seventh
Edition Unix source licencee but, even then, I saw your decision to
make the source of Minix available as liberation from the shackles of
AT&T copyright!!
I think you may sometimes forget that your 'hobby' has had a profound
effect on the availability of 'personal' Unix (ie. affordable Unix) and
that the 8086 PC I ran Minix 1.2 on actually cost me considerably more
than my present 386/SX clone.
Clearly, Minix _cannot_ be all things to all men, but I see the
progress to 386 versions in much the same way that I see 68000 or other
linear address space architectures: it is a good thing for people like
me who use Minix and feel constrained by the segmented architecture of
the PC version for applications.
NOTHING you can say would convince me that I should use Coherent ...
Tony
--
-------------------------------------------------------------------------------
Dr. A.J.Travis <ajt@uk.ac.sari.rri> | Rowett Research Institute,
| Greenburn Road, Bucksburn, Aberdeen,
| AB2 9SB. UK. tel 0224-712751
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From: richard@aiai.ed.ac.uk (Richard Tobin)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 7 Feb 92 14:58:22 GMT
Organization: AIAI, University of Edinburgh, Scotland
In article <12696@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>If you just want to USE the system, instead of hacking on its
>internals, you don't need source code.
Unfortunately hacking on the internals is just what many of us want
the system for... You'll be rid of most of us when BSD-detox or GNU
comes out, which should happen in the next few months (yeah, right).
-- Richard
--
Richard Tobin,
AI Applications Institute, R.Tobin@ed.ac.uk
Edinburgh University.
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From: comm121@unixg.ubc.ca (Louie)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 30 Jan 92 02:55:22 GMT
Organization: University of British Columbia, Vancouver, B.C., Canada
Nntp-Posting-Host: chilko.ucs.ubc.ca
In <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
There are really no other alternatives other than Linux for people like
me who want a "free" OS. Considering that the majority of people who
would use a "free" OS use the 386, portability is really not all that
big of a concern. If I had a Sparc I would use Solaris.
As it stands, I installed Linux with gcc, emacs 18.57, kermit and all of the
GNU utilities without any trouble at all. No need to apply patches. I
just followed the installation instructions. I can't get an OS like
this *anywhere* for the price to do my Computer Science homework. And
it seems like network support and then X-Windows will be ported to Linux
well before Minix. This is something that would be really useful. In my
opinion, portability of standard Unix software is important also.
I know that the design using a monolithic system is not as good as the
microkernel. But for the short term future (And I know I won't/can't
be uprading from my 386), Linux suits me perfectly.
Philip Wu
pwu@unixg.ubc.ca
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Newsgroups: comp.os.minix
From: kevin@nuchat.sccsi.com (Kevin Brown)
Subject: Re: LINUX is obsolete
Organization: Hierarchical
Date: Thu, 30 Jan 1992 01:36:43 GMT
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>I was in the U.S. for a couple of weeks, so I haven't commented much on
>LINUX (not that I would have said much had I been around), but for what
>it is worth, I have a couple of comments now.
>
>As most of you know, for me MINIX is a hobby, something that I do in the
>evening when I get bored writing books and there are no major wars,
>revolutions, or senate hearings being televised live on CNN. My real
>job is a professor and researcher in the area of operating systems.
>
>As a result of my occupation, I think I know a bit about where operating
>are going in the next decade or so. Two aspects stand out:
>
>1. MICROKERNEL VS MONOLITHIC SYSTEM
> Most older operating systems are monolithic, that is, the whole operating
> system is a single a.out file that runs in 'kernel mode.' This binary
> contains the process management, memory management, file system and the
> rest. Examples of such systems are UNIX, MS-DOS, VMS, MVS, OS/360,
> MULTICS, and many more.
>
> The alternative is a microkernel-based system, in which most of the OS
> runs as separate processes, mostly outside the kernel. They communicate
> by message passing. The kernel's job is to handle the message passing,
> interrupt handling, low-level process management, and possibly the I/O.
> Examples of this design are the RC4000, Amoeba, Chorus, Mach, and the
> not-yet-released Windows/NT.
>
> While I could go into a long story here about the relative merits of the
> two designs, suffice it to say that among the people who actually design
> operating systems, the debate is essentially over. Microkernels have won.
> The only real argument for monolithic systems was performance, and there
> is now enough evidence showing that microkernel systems can be just as
> fast as monolithic systems (e.g., Rick Rashid has published papers comparing
> Mach 3.0 to monolithic systems) that it is now all over but the shoutin`.
Of course, there are some things that are best left to the kernel, be it
micro or monolithic. Like things that require playing with the process'
stack, e.g. signal handling. Like memory allocation. Things like that.
The microkernel design is probably a win, all in all, over a monolithic
design, but it depends on what you put in the kernel and what you leave
out.
> MINIX is a microkernel-based system. The file system and memory management
> are separate processes, running outside the kernel. The I/O drivers are
> also separate processes (in the kernel, but only because the brain-dead
> nature of the Intel CPUs makes that difficult to do otherwise).
Minix is a microkernel design, of sorts. The problem is that it gives special
priveleges to mm and fs, when there shouldn't be any (at least for fs). It
also fails to integrate most of the functionality of mm in the kernel itself,
and this makes things like signal handling and memory allocation *really*
ugly. If you did these things in the kernel itself, then signal handling
would be as simple as setting a virtual interrupt vector and causing the
signalled process to receive that interrupt (with the complication that
system calls might have to be terminated. Which means that a message would
have to be sent to every process that is servicing the process' system call,
if any. It's considerations like these that make the monolithic kernel
design appealing).
The *entire* system call interface in Minix needs to be rethought. As it
stands right now, the file system is not just a file system, it's also a
system-call server. That functionality needs to be separated out in order
to facilitate a multiple file system architecture. Message passing is
probably the right way to go about making the call and waiting for it, but
the message should go to a system call server, not the file system itself.
In order to handle all the special caveats of the Unix API, you end up writing
a monolithic "kernel" even if you're using a microkernel base. You end up
with something called a "server", and an example is the BSD server that runs
under Mach.
And, in any case, the message-passing in Minix needs to be completely redone.
As it is, it's a kludge. I've been giving this some thought, but I haven't
had time to do anything with what I've thought of so far. Suffice it to say
that the proper way to do message-passing is probably with message ports
(both public and private), with the various visible parts of the operating
system having public message ports. Chances are, that ends up being the
system call server only, though this will, of course, depend on the goals
of the design.
> LINUX is
> a monolithic style system. This is a giant step back into the 1970s.
> That is like taking an existing, working C program and rewriting it in
> BASIC. To me, writing a monolithic system in 1991 is a truly poor idea.
Depends on the design criteria, as you should know. If your goal is to
design a Unix workalike that is relatively simple and relatively small,
then a monolithic design is probably the right approach for the job, because
unless you're designing for really backwards hardware, the problems of
things like interrupted system calls, memory allocation within the kernel
(so you don't have to statically allocate *everything* in your OS), signal
handling, etc. all go away (or are at least minimized) if you use a
monolithic design. If you want the ability to bring up and take down
file systems, add and remove device drivers, etc., all at runtime, then
a microkernel approach is the right solution.
Frankly, I happen to like the idea of removable device drivers and such,
so I tend to favor the microkernel approach as a general rule.
>2. PORTABILITY
> Once upon a time there was the 4004 CPU. When it grew up it became an
> 8008. Then it underwent plastic surgery and became the 8080. It begat
> the 8086, which begat the 8088, which begat the 80286, which begat the
> 80386, which begat the 80486, and so on unto the N-th generation. In
> the meantime, RISC chips happened, and some of them are running at over
> 100 MIPS. Speeds of 200 MIPS and more are likely in the coming years.
> These things are not going to suddenly vanish. What is going to happen
> is that they will gradually take over from the 80x86 line. They will
> run old MS-DOS programs by interpreting the 80386 in software. (I even
> wrote my own IBM PC simulator in C, which you can get by FTP from
> ftp.cs.vu.nl = 192.31.231.42 in dir minix/simulator.) I think it is a
> gross error to design an OS for any specific architecture, since that is
> not going to be around all that long.
Again, look at the design criteria. If portability isn't an issue, then
why worry about it? While LINUX suffers from lack of portability, portability
was obviously never much of a consideration for its author, who explicitly
stated that it was written as an exercise in learning about the 386
architecture.
And, in any case, while MINIX is portable in the sense that most of the code
can be ported to other platforms, it *still* suffers from the limitations of
the original target machine that drove the walk down the design decision tree.
The message passing is a kludge because the 8088 is slow. The kernel doesn't
do memory allocation (thus not allowing FS and the drivers to get away with
using a malloc library or some such, and thus causing everyone to have to
statically allocate everything), probably due to some other limitation of
the 8088. The very idea of using "clicks" is obviously the result of the
segmented architecture of the 8088. The file system size is too limited
(theoretically fixed in 1.6, but now you have *two* file system formats to
contend with. If having the file system as a separate process is such a
big win, then why don't we have two file system servers, eh? Why simply
extend the existing Minix file system instead of implementing BSD's FFS
or some other high-performance file system? It's not that I'm greedy
or anything... :-).
> MINIX was designed to be reasonably portable, and has been ported from the
> Intel line to the 680x0 (Atari, Amiga, Macintosh), SPARC, and NS32016.
> LINUX is tied fairly closely to the 80x86. Not the way to go.
All in all, I tend to agree.
>Don`t get me wrong, I am not unhappy with LINUX. It will get all the people
>who want to turn MINIX in BSD UNIX off my back. But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
Yeah, right. Point me someplace where I can get a free "modern" OS and I'll
gladly investigate. But the GNU OS is currently vaporware, and as far as I'm
concerned it will be for a LOOOOONG time to come.
Any other players? BSD 4.4 is a monolithic architecture, so by your
definition it's out. Mach is free, but the BSD server isn't (AT&T code,
you know), and in any case, isn't the BSD server something you'd consider
to be a monolithic design???
Really. Why do you think LINUX is as popular as it is? The answer is
simple, of course: because it's the *only* free Unix workalike OS in
existence. BSD doesn't qualify (yet). Minix doesn't qualify. XINU
isn't even in the running. GNU's OS is vaporware, and probably will
be for a long time, so *by definition* it's not in the running. Any
other players? I haven't heard of any...
>Andy Tanenbaum (ast@cs.vu.nl)
Minix is an excellent piece of work. A good starting point for anyone who
wants to learn about operating systems. But it needs rewriting to make it
truly elegant and functional. As it is, there are too many kludges and
hacks (e.g., the message passing).
Kevin Brown
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From: aduncan@rhea.trl.OZ.AU (Allan Duncan)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 2 Feb 92 22:06:26 GMT
Organization: Telecom Research Labs, Melbourne, Australia
From article <1992Jan30.013643.3248@menudo.uh.edu>, by kevin@nuchat.sccsi.com (Kevin Brown):
> The *entire* system call interface in Minix needs to be rethought. As it
> stands right now, the file system is not just a file system, it's also a
> system-call server. That functionality needs to be separated out in order
> to facilitate a multiple file system architecture. Message passing is
> probably the right way to go about making the call and waiting for it, but
> the message should go to a system call server, not the file system itself.
>
> In order to handle all the special caveats of the Unix API, you end up writing
> a monolithic "kernel" even if you're using a microkernel base. You end up
> with something called a "server", and an example is the BSD server that runs
> under Mach.
>
> And, in any case, the message-passing in Minix needs to be completely redone.
> As it is, it's a kludge. I've been giving this some thought, but I haven't
> had time to do anything with what I've thought of so far. Suffice it to say
> that the proper way to do message-passing is probably with message ports
> (both public and private), with the various visible parts of the operating
> system having public message ports. Chances are, that ends up being the
> system call server only, though this will, of course, depend on the goals
> of the design.
It gets to sound more and more like Tripos and the Amiga :-)
Allan Duncan ACSnet aduncan@trl.oz
(+613) 541 6708 Internet aduncan@trl.oz.au
UUCP {uunet,hplabs,ukc}!munnari!trl.oz.au!aduncan
Telecom Research Labs, PO Box 249, Clayton, Victoria, 3168, Australia.
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From: kevin@taronga.taronga.com (Kevin Brown)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 4 Feb 92 08:28:08 GMT
Organization: University of Houston
In article <1992Feb2.220626.25197@trl.oz.au> aduncan@rhea.trl.OZ.AU (Allan Duncan) writes:
>From article <1992Jan30.013643.3248@menudo.uh.edu>, by kevin@nuchat.sccsi.com (Kevin Brown):
>
>> The *entire* system call interface in Minix needs to be rethought. As it
>> stands right now, the file system is not just a file system, it's also a
>> system-call server. That functionality needs to be separated out in order
>> to facilitate a multiple file system architecture. Message passing is
>> probably the right way to go about making the call and waiting for it, but
>> the message should go to a system call server, not the file system itself.
>>
>> In order to handle all the special caveats of the Unix API, you end up writing
>> a monolithic "kernel" even if you're using a microkernel base. You end up
>> with something called a "server", and an example is the BSD server that runs
>> under Mach.
>>
>> And, in any case, the message-passing in Minix needs to be completely redone.
>> As it is, it's a kludge. I've been giving this some thought, but I haven't
>> had time to do anything with what I've thought of so far. Suffice it to say
>> that the proper way to do message-passing is probably with message ports
>> (both public and private), with the various visible parts of the operating
>> system having public message ports. Chances are, that ends up being the
>> system call server only, though this will, of course, depend on the goals
>> of the design.
>
>It gets to sound more and more like Tripos and the Amiga :-)
There's no question that many of my ideas spring from the architecture
of the Amiga's operating system. It's pretty impressive to see a
message-passing, multitasking operating system that operates as fast
as the Amiga's OS does on hardware that slow. They did a lot of things
right.
There are some ideas that, I think, are my own. Or, at least, that I've
developed independently. For example, if you have a message-passing
system that includes the option to transfer message memory ownership to the
target process, then it naturally follows that you can globally optimize the
use of your block cache by making your block cache global with respect
to *all* filesystems. The filesystem code requests blocks from the
block cache manager and tells the block cache manager what device driver
to call and what parameters to send it when flushing the block. The block
cache manager replies with a message that is the size of a block (or, if
you wish to allocate several at a time, several blocks). Since
ownership is transferred as a result of passing the message, the block
cache manager can allocate the memory itself, optionally flushing as
many blocks as it needs in order to free up enough to send to the caller.
The block cache manager is, of course, a user process. If the filesystem
code is written right, you can kill the block cache manager in order to
disable the block cache. The filesystem will simply do its thing
unbuffered. Makes for a slow system, but at least you can do it. You
can also change the behavior of the buffer cache by sending control
messages to the cache manager. Can you say "tunable parameters"? :-)
You could also accomplish this with some sort of shared memory, but this
would require semaphore control of the allocation list. You'd also have
to figure out a way to flush bits of the cache when needed (easy to do
if you're a monolithic kernel, but I'm referring to a microkernel) without
colliding with another process writing into the block. Semaphore control
of the individual blocks as well?
>Allan Duncan ACSnet aduncan@trl.oz
>(+613) 541 6708 Internet aduncan@trl.oz.au
> UUCP {uunet,hplabs,ukc}!munnari!trl.oz.au!aduncan
>Telecom Research Labs, PO Box 249, Clayton, Victoria, 3168, Australia.
Kevin Brown
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From: dgraham@bmers30.bnr.ca (Douglas Graham)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 1 Feb 92 00:26:30 GMT
Organization: Bell-Northern Research, Ottawa, Canada
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
> While I could go into a long story here about the relative merits of the
> two designs, suffice it to say that among the people who actually design
> operating systems, the debate is essentially over. Microkernels have won.
Can you recommend any (unbiased) literature that points out the strengths
and weaknesses of the two approaches? I'm sure that there is something
to be said for the microkernel approach, but I wonder how closely
Minix resembles the other systems that use it. Sure, Minix uses lots
of tasks and messages, but there must be more to a microkernel architecture
than that. I suspect that the Minix code is not split optimally into tasks.
> The only real argument for monolithic systems was performance, and there
> is now enough evidence showing that microkernel systems can be just as
> fast as monolithic systems (e.g., Rick Rashid has published papers comparing
> Mach 3.0 to monolithic systems) that it is now all over but the shoutin`.
My main complaint with Minix is not it's performance. It is that adding
features is a royal pain -- something that I presume a microkernel
architecure is supposed to alleviate.
> MINIX is a microkernel-based system.
Is there a consensus on this?
> LINUX is
> a monolithic style system. This is a giant step back into the 1970s.
> That is like taking an existing, working C program and rewriting it in
> BASIC. To me, writing a monolithic system in 1991 is a truly poor idea.
This is a fine assertion, but I've yet to see any rationale for it.
Linux is only about 12000 lines of code I think. I don't see how
splitting that into tasks and blasting messages around would improve it.
>Don`t get me wrong, I am not unhappy with LINUX. It will get all the people
>who want to turn MINIX in BSD UNIX off my back. But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
Well, there are no other choices that I'm aware of at the moment. But
when GNU OS comes out, I'll very likely jump ship again. I sense that
you *are* somewhat unhappy about Linux (and that surprises me somewhat).
I would guess that the reason so many people embraced it, is because it
offers more features. Your approach to people requesting features in
Minix, has generally been to tell them that they didn't really want that
feature anyway. I submit that the exodus in the direction of Linux
proves you wrong.
Disclaimer: I had nothing to do with Linux development. I just find
it an easier system to understand than Minix.
--
Doug Graham dgraham@bnr.ca My opinions are my own.
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From: peter@ferranti.com (peter da silva)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 17:40:06 GMT
Organization: Xenix Support, FICC
In article <1992Feb01.002630.14861@bmerh2.bnr.ca> dgraham@bmers30.bnr.ca (Douglas Graham) writes:
> Minix resembles the other systems that use it. Sure, Minix uses lots
> of tasks and messages, but there must be more to a microkernel architecture
> than that. I suspect that the Minix code is not split optimally into tasks.
Definitely. Minix shows you how a microkernel works, but it sure doesn't show
you why you would use one.
A couple of years ago I brought this up with Andy, and his response indicated
that he was himself not convinced of the superiority of the microkernel design
at the time. He said (as near as I can recall... this is a paraphrase) that a
message passing design was inherently slower than a monolithic one... which was
news to me: I had (and still have) a PC that was MUCH more responsive than any
UNIX box I ever touched using a message-passing design.
> > MINIX is a microkernel-based system.
> Is there a consensus on this?
Yes, it's not a well-factored one, and there's no API to the microkernel
interface, but it's a microkernel design.
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: hedrick@klinzhai.rutgers.edu (Charles Hedrick)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 1 Feb 92 00:27:04 GMT
Organization: Rutgers Univ., New Brunswick, N.J.
The history of software shows that availability wins out over
technical quality every time. That's Linux' major advantage. It's a
small 386-based system that's fairly compatible with generic Unix, and
is freely available. I dropped out of the Minix community a couple of
years ago when it became clear that (1) Minix was not going to take
advantage of anything beyond the 8086 anytime in the near future, and
(2) the licensing -- while amazingly friendly -- still made it hard
for people who were interested in producing a 386 version. Several
people apparently did nice work for the 386. But all they could
distribute were diffs. This made bringing up a 386 system a job that
isn't practical for a new user, and in fact I wasn't sure I wanted to
do it.
I apologize if things have changed in the last couple of years. If
it's now possible to get a 386 version in a form that's ready to run,
the community has developed a way to share Minix source, and bringing
up normal Unix programs has become easier in the interim, then I'm
willing to reconsider Minix. I do like its design.
It's possible that Linux will be overtaken by Gnu or a free BSD.
However, if the Gnu OS follows the example of all other Gnu software,
it will require a system with 128MB of memory and a 1GB disk to use.
There will still be room for a small system. My ideal OS would be 4.4
BSD. But 4.4's release date has a history of extreme slippage. With
most of their staff moving to BSDI, it's hard to believe that this
situation is going to be improved. For my own personal use, the BSDI
system will probably be great. But even their very attractive pricing
is likely to be too much for most of our students, and even though
users can get source from them, the fact that some of it is
proprietary will again mean that you can't just put altered code out
for public FTP. At any rate, Linux exists, and the rest of these
alternatives are vapor.
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From: nhc@cbnewsj.cb.att.com (n.h.chandler)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Summary: How can I get a copy of Linux?
Date: 2 Feb 92 01:38:51 GMT
Organization: AT&T Bell Laboratories
I have been following the Minix/Linux discussion. How
can I get a copy of Linux?
Neville H. Chandler
cbnewsj!nhc@att.com
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From: tytso@athena.mit.edu (Theodore Y. Ts'o)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 31 Jan 92 21:40:23 GMT
Organization: Massachusetts Institute of Technology
In-Reply-To: ast@cs.vu.nl's message of 29 Jan 92 12: 12:50 GMT
Nntp-Posting-Host: sos.mit.edu
>From: ast@cs.vu.nl (Andy Tanenbaum)
>ftp.cs.vu.nl = 192.31.231.42 in dir minix/simulator.) I think it is a
>gross error to design an OS for any specific architecture, since that is
>not going to be around all that long.
It's not your fault for believing that Linux is tied to the 80386
architecture, since many Linux supporters (including Linus himself) have
made the this statement. However, the amount of 80386-specific code is
probably not much more than what is in a Minix implementation, and there
is certainly a lot less 80386 specific code in Linux than here is
Vax-specific code in BSD 4.3.
Granted, the port to other architectures hasn't been done yet. But if I
were going to bring up a Unix-like system on a new architecture, I'd
probably start with Linux rather than Minix, simply because I want to
have some control over what I can do with the resulting system when I'm
done with it. Yes, I'd have to rewrite large portions of the VM and
device driver layers --- but I'd have to do that with any other OS.
Maybe it would be a little bit harder than it would to port Minix to the
new architecture; but this would probably be only true for the first
architecture that we ported Linux to.
>While I could go into a long story here about the relative merits of the
>two designs, suffice it to say that among the people who actually design
>operating systems, the debate is essentially over. Microkernels have won.
>The only real argument for monolithic systems was performance, and there
>is now enough evidence showing that microkernel systems can be just as
>fast as monolithic systems (e.g., Rick Rashid has published papers comparing
>Mach 3.0 to monolithic systems) that it is now all over but the shoutin`.
This is not necessarily the case; I think you're painting a much more
black and white view of the universe than necessarily exists. I refer
you to such papers as Brent Welsh's (welch@parc.xerox.com) "The
Filsystem Belongs in the Kernel" paper, where in he argues that the
filesystem is a mature enough abstraction that it should live in the
kernel, not outside of it as it would in a strict microkernel design.
There also several people who have been concerned about the speed of
OSF/1 Mach when compared with monolithic systems; in particular, the
nubmer of context switches required to handle network traffic, and
networked filesystems in particular.
I am aware of the benefits of a micro kernel approach. However, the
fact remains that Linux is here, and GNU isn't --- and people have been
working on Hurd for a lot longer than Linus has been working on Linux.
Minix doesn't count because it's not free. :-)
I suspect that the balance of micro kernels versus monolithic kernels
depend on what you're doing. If you're interested in doing research, it
is obviously much easier to rip out and replace modules in a micro
kernel, and since only researchers write papers about operating systems,
ipso facto micro kernels must be the right approach. However, I do know
a lot of people who are not researchers, but who are rather practical
kernel programmers, who have a lot of concerns over the cost of copying
and the cost of context switches which are incurred in a micro kernel.
By the way, I don't buy your arguments that you don't need a
multi-threaded filesystem on a single user system. Once you bring up a
windowing system, and have a compile going in one window, a news reader
in another window, and UUCP/C News going in the background, you want
good filesystem performance, even on a single-user system. Maybe to a
theorist it's an unnecessary optimization and a (to use your words)
"performance hack", but I'm interested in a Real operating system ---
not a research toy.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Theodore Ts'o bloom-beacon!mit-athena!tytso
308 High St., Medford, MA 02155 tytso@athena.mit.edu
Everybody's playing the game, but nobody's rules are the same!
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*** EOOH ***
From: peter@ferranti.com (peter da silva)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 3 Feb 92 17:32:54 GMT
Organization: Xenix Support, FICC
In article <TYTSO.92Jan31164013@SOS.mit.edu> tytso@athena.mit.edu (Theodore Y. Ts'o) writes:
> This is not necessarily the case; I think you're painting a much more
> black and white view of the universe than necessarily exists. I refer
> you to such papers as Brent Welsh's (welch@parc.xerox.com) "The
> Filsystem Belongs in the Kernel" paper, where in he argues that the
> filesystem is a mature enough abstraction that it should live in the
> kernel, not outside of it as it would in a strict microkernel design.
What does "a mature enough abstraction" mean, here? Things don't move
into the kernel simply because they're now considered safe and stable
enough, but because they're too inefficient when they're outside it or
they lose functionality by being outside it, and there's no easy fix.
The Amiga operating system certainly benefits from having a file system
outside the kernel. There are dozens of file systems, many of them written
by hobbyists, available. Ideas like "assigned paths" can be played with
in the file system without breaking stuff. All these file systems have a
common interface and so look to the application as part of the operating
system, but just because something is on the other side of the API doesn't
mean it is, or belongs, in the kernel.
> There also several people who have been concerned about the speed of
> OSF/1 Mach when compared with monolithic systems; in particular, the
> nubmer of context switches required to handle network traffic, and
> networked filesystems in particular.
If this is because the networking was moved out of the kernel, I consider
it a price well worth paying. Having networking code in the kernel is the
source of many subtle bugs in networks. Just for something that bit us,
what happens if you need to get to the upper level driver before you can
acknowledge a packet, but the process that you need to run is hung up in
the tty driver waiting for a ^Q?
Something *I* would have expected to find in the kernel before now, yet
isn't, is windowing systems. With a microkernel (and the associated lower
*cost* of a context switch) you can get much of the advantages of a kernel
window system without paying the cost in complexity.
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: joe@jshark.rn.com
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 31 Jan 92 13:21:44 GMT
Organization: a blip of entropy
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
> MINIX was designed to be reasonably portable, and has been ported from the
> Intel line to the 680x0 (Atari, Amiga, Macintosh), SPARC, and NS32016.
> LINUX is tied fairly closely to the 80x86. Not the way to go.
If you looked at the source instead of believing the author, you'd realise
this is not true!
He's replaced 'fubyte' by a routine which explicitly uses a segment register
- but that could be easily changed. Similarly, apart from a couple of places
which assume the '386 MMU, a couple of macros to hide the exact page sizes
etc would make porting trivial. Using '386 TSS's makes the code simpler,
but the VAX and WE32000 have similar structures.
As he's already admitted, a bit of planning would have the the system
neater, but merely putting '386 assembler around isn't a crime!
And with all due respect:
- the Book didn't make an issue of portability (apart from a few
"#ifdef M8088"s)
- by the time it was released, Minix had come to depend on several
8086 "features" that caused uproar from the 68000 users.
>Andy Tanenbaum (ast@cs.vu.nl)
joe.
--
joe@jshark.rn.com
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*** EOOH ***
From: joe@jshark.rn.com
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 2 Feb 92 23:59:12 GMT
Organization: Jshark Communications
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>I was in the U.S. for a couple of weeks, so I haven't commented much on
>LINUX (not that I would have said much had I been around), but for what
>it is worth, I have a couple of comments now.
Maybe keepng quiet would have been best.
>1. MICROKERNEL VS MONOLITHIC SYSTEM
>
> While I could go into a long story here about the relative merits of the
> two designs, suffice it to say that among the people who actually design
> operating systems, the debate is essentially over.
No, MS-DOS won. Sad, but there you are. 60 million: Next
It would be churlish to point out that MS-DOS has loadable device drivers
and that VMS is now (basically)a set of loadable service modules and drivers.
"Microkernel" was the buzz-word of last year, so Minix is a microkernel.
"Object-oriented" is this years, so Minix is object-oriented - right?
joe.
----
joe@jshark.rn.com
uunet!nstar!jshark!joe
I'm a mutated .sig virus, I got this from Henry Spencer's:
"As a user, I'll take speed over features anyday" - A Tanenbaum
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From: entropy@wintermute.WPI.EDU (Lawrence C. Foard)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 5 Feb 92 14:56:30 GMT
Organization: Worcester Polytechnic Institute
Nntp-Posting-Host: wintermute.wpi.edu
In article <12595@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>Don`t get me wrong, I am not unhappy with LINUX. It will get all the people
>who want to turn MINIX in BSD UNIX off my back. But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
I believe you have some valid points, although I am not sure that a
microkernel is necessarily better. It might make more sense to allow some
combination of the two. As part of the IPC code I'm writting for Linux I am
going to include code that will allow device drivers and file systems to run
as user processes. These will be significantly slower though, and I believe it
would be a mistake to move everything outside the kernel (TCP/IP will be
internal).
Actually my main problem with OS theorists is that they have never tested
there ideas! None of these ideas (with a partial exception for MACH) has ever
seen the light of day. 32 bit home computers have been available for almost a
decade and Linus was the first person to ever write a working OS for them
that can be used without paying AT&T $100,000. A piece of software in hand is
worth ten pieces of vaporware, OS theorists are quick to jump all over an OS
but they are unwilling to ever provide an alternative.
The general consensus that Micro kernels is the way to go means nothing when
a real application has never even run on one.
The release of Linux is allowing me to try some ideas I've been wanting to
experment with for years, but I have never had the opportunity to work with
source code for a functioning OS.
--
Disclaimer: Opinions are based on logic rather than biblical "fact". ------
Hackers do it for fun. | First they came for the drug users, I said \ /
"Profesionals" do it for money. | nothing, then they came for hackers, \ /
Managers have others do it for them. | I said nothing... STOP W.O.D. \/
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 5 Feb 92 23:33:23 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>Actually my main problem with OS theorists is that they have never tested
>there ideas!
I'm mortally insulted. I AM NOT A THEORIST. Ask anybody who was at our
department meeting yesterday (in joke).
Actually, these ideas have been very well tested in practice. OSF is betting
its whole business on a microkernel (Mach 3.0). USL is betting its business
on another one (Chorus). Both of these run lots of software, and both have
been extensively compared to monolithic systems. Amoeba has been fully
implemented and tested for a number of applications. QNX is a microkernel
based system, and someone just told me the installed base is 200,000 systems.
Microkernels are not a pipe dream. They represent proven technology.
The Mach guys wrote a paper called "UNIX as an application program."
It was by Golub et al., in the Summer 1990 USENIX conference. The Chorus
people also have a technical report on microkernel performance, and I
coauthored another paper on the subject, which I mentioned yesterday
(Dec. 1991 Computing Systems). Check them out.
Andy Tanenbaum (ast@cs.vu.nl)
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From: wolff@neuron.et.tudelft.nl (Rogier Wolff)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 8 Feb 92 09:13:39 GMT
Organization: Delft University of Technology, Dept. of Electrical Engineering
Nntp-Posting-Host: neuron.et.tudelft.nl
ast@cs.vu.nl (Andy Tanenbaum) writes:
>In article <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>>Actually my main problem with OS theorists is that they have never tested
>>there ideas!
>I'm mortally insulted. I AM NOT A THEORIST. Ask anybody who was at our
>department meeting yesterday (in joke).
>Actually, these ideas have been very well tested in practice.
The problem is that to really do an unbiased test you would need two
*identical* teams, and ask them to make two OS's, for the same
destination machine, one using a microkernel architecture, and the other
using the monolithic approach. This is in practice not feasable and the
publications on the subject can only shout: "look: I've got a good
performance using a microkernel", "we've got very good performance using
a monolithic aproach" or "it only took us X months to implement this OS"
If people did benchmark their OS's they wrote the OS for one architecture,
and adapted it to test the other. This adaptation will naturally degrade
performance, and show that the designers were right in the first place.
Anyway, anybody have an opinion about the fact that code for printf
is included three times in the Minix OS when it runs (once in the
kernel, MM and FS)
Roger
--
If the opposite of "pro" is "con", what is the opposite of "progress"?
(stolen from kadokev@iitvax ==? technews@iitmax.iit.edu)
EMail: wolff@duteca.et.tudelft.nl ** Tel +31-15-783644 or +31-15-142371
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 8 Feb 92 15:04:31 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
In article <1992Feb08.091339.16121@donau.et.tudelft.nl> wolff@neuron.et.tudelft.nl (Rogier Wolff) writes:
>Anyway, anybody have an opinion about the fact that code for printf
>is included three times in the Minix OS when it runs (once in the
>kernel, MM and FS)
Back in the yore days, this might have been a problem. I remember when
every program, even wordprocessors, had to be written in assembler to
squeeze them down to the smallest size possible for a 64K system. One
of the reasons WordPerfect is such a mess today is that it was written
in assembler instead of C.
Now, even the small systems which Minix runs have at least 640K, so a
few wasted bytes are not so much of a problem.
Why not write Linux in 80386 assembler? It would be smaller and even
faster. And don't forget to code inline as much as possible, to avoid
the crippling overhead of function calls. And leave out comments,
because they waste disk space.
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
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From: cs2@doc.ic.ac.uk (Christopher Stuart)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 11 Feb 92 13:52:57 GMT
Organization: Department of Computing, Imperial College, University of London, UK.
Nntp-Posting-Host: oak10.doc.ic.ac.uk
Article 18297 of comp.os.minix:
Path: icdoc!uknet!mcsun!uunet!cis.ohio-state.edu!rutgers!news-server.csri.toronto.edu!utgpu!news-server.ecf!epas!meggin
From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Message-ID: <1992Feb8.150431.11030@epas.toronto.edu>
Date: 8 Feb 92 15:04:31 GMT
References: <1992Feb5.145630.759@wpi.WPI.EDU> <12747@star.cs.vu.nl> <1992Feb08.091339.16121@donau.et.tudelft.nl>
Sender: news@epas.toronto.edu (USENET)
Organization: University of Toronto - EPAS
Lines: 28
Nntp-Posting-Host: epas.utoronto.ca
In article <1992Feb08.091339.16121@donau.et.tudelft.nl> wolff@neuron.et.tudelft.nl (Rogier Wolff) writes:
>Anyway, anybody have an opinion about the fact that code for printf
>is included three times in the Minix OS when it runs (once in the
>kernel, MM and FS)
Back in the yore days, this might have been a problem. I remember when
every program, even wordprocessors, had to be written in assembler to
squeeze them down to the smallest size possible for a 64K system. One
of the reasons WordPerfect is such a mess today is that it was written
in assembler instead of C.
Now, even the small systems which Minix runs have at least 640K, so a
few wasted bytes are not so much of a problem.
Why not write Linux in 80386 assembler? It would be smaller and even
faster. And don't forget to code inline as much as possible, to avoid
the crippling overhead of function calls. And leave out comments,
because they waste disk space.
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
--
/*----------------------------------------------------------------------------*/
/* Christopher Stuart: cs2@doc.ic.ac.uk */
/* Dept. Computing, Imperial College, London. */
/*----------------------------------------------------------------------------*/
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From: peter@ferranti.com (peter da silva)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 10 Feb 92 03:10:00 GMT
Organization: Xenix Support, FICC
In article <1992Feb08.091339.16121@donau.et.tudelft.nl> wolff@neuron.et.tudelft.nl (Rogier Wolff) writes:
> The problem is that to really do an unbiased test you would need two
> *identical* teams, and ask them to make two OS's [...]
No, you don't. I don't think there's any question that a macrokernel is
very easy to get decent performance out of. Where the microkernel design
has a major advantage is in flexibility. Adding stuff to a macrokernel
is fairly complex and quickly becomes pretty gross. Look at BSD or System V
for examples. Adding stuff to a well designed microkernel is VERY easy.
Sometimes you don't want to compare oranges and oranges. Sometimes you want
to compare concentrated orange juice with fresh-squeezed. Fresh-squeezed
takes longer, but it's worth it.
Plus, with a microkernel you can get much better context switching between
microtasks than macro processes. So you can do stuff in separate processes
that would be out of the question in a macrokernel, and avoid nonsense like
the myriad inconsistencies in NFS.
> anyone have an opinion about why the code for printf
> is included three times in the Minix OS when it runs (once in the
> kernel, MM and FS)
Anyone have an opinion why the code for printf is included only once in
AmigaOS (even though the AmigaOS 2.04 "kernel" is actually a dozen or
more separate processes)?
Minix is a poor technology demonstrator for microkernels. Which is OK, since
it wasn't supposed to be one.
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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Newsgroups: comp.os.minix
From: peter@ferranti.com (peter da silva)
Subject: Re: LINUX is obsolete
Organization: Xenix Support, FICC
Date: Thu, 6 Feb 1992 16:02:47 GMT
In article <12747@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
> QNX is a microkernel
> based system, and someone just told me the installed base is 200,000 systems.
Oh yes, while I'm on the subject... there are over 3 million Amigas out there,
which means that there are more of them than any UNIX vendor has shipped, and
probably more than all UNIX systems combined.
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: tim@maths.tcd.ie (Timothy Murphy)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 6 Feb 92 11:14:59 GMT
Organization: Dept. of Maths, Trinity College, Dublin, Ireland.
Nntp-Posting-Host: salmon
In <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>32 bit home computers have been available for almost a
>decade and Linus was the first person to ever write a working OS for them
>that can be used without paying AT&T $100,000. A piece of software in hand is
>worth ten pieces of vaporware, OS theorists are quick to jump all over an OS
>but they are unwilling to ever provide an alternative.
Surely Bruce Evans' 386-Minix preceded Linux?
(Diffs for PC-Minix -> 386-Minix
available from archive-server@plains.nodak.edu
in the directory Minix/oz)
--
Timothy Murphy
e-mail: tim@maths.tcd.ie
tel: +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland
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From: ts@cup.portal.com (Tim W Smith)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 7 Feb 92 02:09:23 GMT
Organization: The Portal System (TM)
> Actually my main problem with OS theorists is that they have never tested
> there ideas! None of these ideas (with a partial exception for MACH) has ever
> seen the light of day. 32 bit home computers have been available for almost a
> decade and Linus was the first person to ever write a working OS for them
> that can be used without paying AT&T $100,000. A piece of software in hand is
How about Netware 386 from Novell? It seems to work.
Tim Smith
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Newsgroups: comp.os.minix
From: peter@ferranti.com (peter da silva)
Subject: Re: LINUX is obsolete
Organization: Xenix Support, FICC
Date: Thu, 6 Feb 1992 16:00:22 GMT
In article <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
> Actually my main problem with OS theorists is that they have never tested
> there ideas!
I beg to differ... there are many microkernel operating systems out there
for everything from an 8088 (QNX) up to large research systems.
> None of these ideas (with a partial exception for MACH) has ever
> seen the light of day. 32 bit home computers have been available for almost a
> decade and Linus was the first person to ever write a working OS for them
> that can be used without paying AT&T $100,000.
I must have been imagining AmigaOS, then. I've been using a figment of my
imagination for the past 6 years.
AmigaOS is a microkernel message-passing design, with better response time
and performance than any other readily available PC operating system: including
MINIX, OS/2, Windows, MacOS, Linux, UNIX, and *certainly* MS-DOS.
The microkernel design has proven invaluable. Things like new file systems
that are normally available only from the vendor are hobbyist products on
the Amiga. Device drivers are simply shared libraries and tasks with specific
entry points and message ports. So are file systems, the window system, and
so on. It's a WONDERFUL design, and validates everything that people have
been saying about microkernels. Yes, it takes more work to get them off the
ground than a coroutine based macrokernel like UNIX, but the versatility
pays you back many times over.
I really wish Andy would do a new MINIX based on what has been learned since
the first release. The factoring of responsibilities in MINIX is fairly poor,
but the basic concept is good.
> The general consensus that Micro kernels is the way to go means nothing when
> a real application has never even run on one.
I'm dreaming again. I sure throught Deluxe Paint, Sculpt 3d, Photon Paint,
Manx C, Manx SDB, Perfect Sound, Videoscape 3d, and the other programs I
bought for my Amiga were "real". I'll have to send the damn things back now,
I guess.
The availability of Linux is great. I'm delighted it exists. I'm sure that
the macrokernel design is one reason it has been implemented so fast, and this
is a valid reason to use macrokernels. BUT... this doesn't mean that
microkernels are inherently slow, or simply research toys.
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: dsmythe@netcom.COM (Dave Smythe)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 10 Feb 92 07:08:22 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)
In article <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>Actually my main problem with OS theorists is that they have never tested
>there ideas! None of these ideas (with a partial exception for MACH) has ever
>seen the light of day.
David Cheriton (Prof. at Stanford, and author of the V system) said something
similar to this in a class in distributed systems. Paraphrased:
"There are two kinds of researchers: those that have implemented
something and those that have not. The latter will tell you that
there are 142 ways of doing things and that there isn't consensus
on which is best. The former will simply tell you that 141 of
them don't work."
He really rips on the OSI-philes as well, for a similar reason. The Internet
protocols are adapted only after having been in use for a period of time,
preventing things from getting standardized that will never be implementable
in a reasonable fashion. OSI adherents, on the other hand, seem intent on
standardizing everything possible, including "escapes" from the standard,
before a reasonable reference implementation exists. Consequently, you see
obsolete ideas immortalized, such as sub-byte-level data field packing,
which makes good performance difficult when your computer is drinking from
a 10+ Gbs fire-hose :-).
Just my $.02
D
--
========================================================================
Dave Smythe N6XLP dsmythe@netcom.com (also dsmythe@cs.stanford.edu)
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From: mitchell@mdd.comm.mot.com (Bill Mitchell)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 10 Feb 92 15:03:51 GMT
Reply-To: mitchell@mdd.comm.mot.com (Bill Mitchell)
Organization: Motorola, Mobile Data Division - Seattle, WA
Bcc: mitchell
in comp.os.minix, dsmythe@netcom.COM (Dave Smythe) said:
>In article <1992Feb5.145630.759@wpi.WPI.EDU> entropy@wintermute.WPI.EDU (Lawrence C. Foard) writes:
>
>David Cheriton (Prof. at Stanford, and author of the V system) said something
>similar to this in a class in distributed systems. Paraphrased:
>
> "There are two kinds of researchers: those that have implemented
> something and those that have not. The latter will tell you that
> there are 142 ways of doing things and that there isn't consensus
> on which is best. The former will simply tell you that 141 of
> them don't work."
>
Yeah, but what's the odds on two who have implemented something differently
agreeing on which 141 don't work?
--
mitchell@mdd.comm.mot.com (Bill Mitchell)
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From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: Apologies (was Re: LINUX is obsolete)
Date: 30 Jan 92 15:38:16 GMT
Organization: University of Helsinki
In article <1992Jan29.231426.20469@klaava.Helsinki.FI> I wrote:
>Well, with a subject like this, I'm afraid I'll have to reply.
And reply I did, with complete abandon, and no thought for good taste
and netiquette. Apologies to ast, and thanks to John Nall for a friendy
"that's not how it's done"-letter. I over-reacted, and am now composing
a (much less acerbic) personal letter to ast. Hope nobody was turned
away from linux due to it being (a) possibly obsolete (I still think
that's not the case, although some of the criticisms are valid) and (b)
written by a hothead :-)
Linus "my first, and hopefully last flamefest" Torvalds
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Newsgroups: comp.os.minix
From: jkp@cs.HUT.FI (Jyrki Kuoppala)
Subject: ast's comments on OS's [was Re: LINUX is obsolete]
In-Reply-To: ast@cs.vu.nl (Andy Tanenbaum)
Nntp-Posting-Host: sauna.cs.hut.fi
Reply-To: jkp@cs.HUT.FI (Jyrki Kuoppala)
Organization: Helsinki University of Technology, Finland
Date: Fri, 31 Jan 1992 12:07:46 GMT
In article <12595@star.cs.vu.nl>, ast@cs (Andy Tanenbaum) writes:
>who want to turn MINIX in BSD UNIX off my back. But in all honesty, I would
>suggest that people who want a **MODERN** "free" OS look around for a
>microkernel-based, portable OS, like maybe GNU or something like that.
I hear bsd 4.4 might also become free and appear in the near future
for the 386, also someone's supposed to be working on bsd 4.4 on top
of the Mach microkernel, and then there's of course GNU. Currently of
course for many people Linux is the OS to use because it's here now,
is free and works.
>P.S. Just as a random aside, Amoeba has a UNIX emulator (running in user
>space), but it is far from complete. If there are any people who would
>like to work on that, please let me know. To run Amoeba you need a few 386s,
>one of which needs 16M, and all of which need the WD Ethernet card.
A note here, the sources I've seen seem to imply that Amoeba will not
be free as in you won't be able to use it, copy it, enhance it, share
it etc. without paying $$ and/or asking permission from someone.
//Jyrki
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Newsgroups: comp.os.minix
From: geoff@world.std.com (Geoff Collyer)
Subject: posixiation (was Re: LINUX is obsolete)
Organization: The World @ Software Tool & Die
Date: Fri, 31 Jan 1992 01:13:00 GMT
Andy Tanenbaum:
>MINIX was designed before POSIX, and is now being (slowly) POSIXized as
>everyone who follows this newsgroup knows.
May I recommend the use of the verb "posixiate" (by analogy with
asphyxiate) instead of "posixize"? Similarly, I prefer "ansitise"
(converse and anagram of "sanitise") to "ansify".
--
Geoff Collyer world.std.com!geoff, uunet.uu.net!geoff
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From: pmacdona@sanjuan (Peter MacDonald)
Newsgroups: comp.os.minix
Subject: re: Linux is obsolete
Date: 1 Feb 92 02:10:06 GMT
Organization: University of Victoria, Victoria, BC, CANADA
Nntp-Posting-Host: sanjuan.uvic.ca
Since I think I posted one of the earliest messages in all this discussion
of Minix vs Linux, I feel compelled to comment on my reasons for
switching from Minix to Linux. In order of importance they are:
1) Linux is free
2) Linux is evolving at a satisfactory clip (because new features
are accepted into the distribution by Linus).
The first requires some explanation, because if I have already purchased
Minix, what posssible concern could price have for me? Simple.
If the OS is free, many more people will use/support/enhance it.
This is also the same reasoning I used when I bought my 386 instead
of a sparc (which I could have got for just 30% more). Since
PCs are cheap and generally available, more people will buy/use
them and thus good, cheap/free software will be abundant.
The second should be pretty obvious to anyone who has been using Minix
for for any period of time. AST generally does not accept enhancements
to Minix. This is not meant as a challenge, but merely a statement of
fact. AST has good and legitimate reasons for this, and I do not dispute
them. But Minix has some limitations which I just could no longer
live with, and due to this policy, the prospect of seeing them resolved
in reasonable time was unsatisfactory. These limitations include:
no 386 support
no virtual consoles
no soft links
no select call
no ptys
no demand paging/swapping/shared-text/shared-libs... (efficient mm)
chmem (inflexible mm)
no X-Windows (advocated for the same reasons as Linux and the 386).
no TCP/IP
no GNU/SysV integration (portability)
Some of these could be fixed by patches (and if you have done this
yourself, I don't have to tell you how satisfactory that is), but at
least the last 5 items were/are beyond any reasonable expectation.
Finally, my comment (crack?) about Minix's segmented kernel, or
micro-kernel architecture was more an expression of my frustration/
bewilderment at attempting to use the Minix PTY patches as a guide
of how to do it under Linux. That particular instance was one where
message passing greatly complicated the implementation of a feature.
I do have an opinion about Monlithic vs Message Passing, but won't
express it now, and did not mean to expresss it then. My goals are
totally short term (maximum functionality in the minimum amount of
time/cost/hassle), and so my views on this are irrelevant, and should
not be misconstrued. If you are non-plussed by the lack of the above
features, then you should consider Minix, as long as you don't mind
paying of course :)
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From: ts@cup.portal.com (Tim W Smith)
Newsgroups: comp.os.minix
Subject: re: Linux is obsolete
Date: 7 Feb 92 01:52:51 GMT
Organization: The Portal System (TM)
Someone says:
> If the OS is free, many more people will use/support/enhance it.
> This is also the same reasoning I used when I bought my 386 instead
> of a sparc (which I could have got for just 30% more). Since
> PCs are cheap and generally available, more people will buy/use
> them and thus good, cheap/free software will be abundant.
Good cheap/free software will also become redundant. Who cares if the
cheap machine has fifteen versions of everything available and the
more expensive machine only has one or two, if the one or two are
good?
The only real exception to this seems to be games. A lot of games seem
to only become available on one system.
Tim Smith
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From: jmaynard@oac.hsc.uth.tmc.edu (Jay Maynard)
Newsgroups: comp.os.minix
Subject: Re: Linux is obsolete
Date: 7 Feb 92 11:59:55 GMT
Organization: UT Health Science Center Houston
Nntp-Posting-Host: oac.hsc.uth.tmc.edu
In article <54087@cup.portal.com> ts@cup.portal.com (Tim W Smith) writes:
>Good cheap/free software will also become redundant. Who cares if the
>cheap machine has fifteen versions of everything available and the
>more expensive machine only has one or two, if the one or two are
>good?
I do, if the one or two versions available are implemented in a fashion I have
some kind of problem with.
--
Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can
jmaynard@oac.hsc.uth.tmc.edu | adequately be explained by a .sig virus.
"IMHO, USENET includes printing out articles and sticking them on my fridge
with little magnets." -- Charles Geyer
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From: olaf@oski.toppoint.de (Olaf Schlueter)
Newsgroups: comp.os.minix
Subject: Re: Linux is obsolete
Date: 7 Feb 92 11:41:44 GMT
Organization: Toppoint Mailbox e.V.
Just a few comments to the discussion of Linux vs Minix, which evolved
partly to a discussion of monolithic vs micro-kernel.
I think there will be no aggreement between the two parties advocating
either concept, if they forget, that Linux and Minix have been designed
for different applications. If you want a cheap, powerful and
enhancable Unix system running on a single machine, with the possibility
to adapt standard Unix software without pain, then Linux is for you. If
you are interested in modern operating system concepts, and want to
learn how a microkernel based system works, then Minix is the better
choice.
It is not an argument against microkernel system, that for the time
being monolithic implemenations of Unix on PCs have a better
performance. This means only, that Unix is maybe better implemented as
a monolithic OS, at least as long as it runs on a single machine. From
the users point of view, the internal design of the OS doesn't matter at
all. Until it comes to networks. On the monolithic approach, a file
server will become a user process based on some hardware facility like
ethernet. Programs which want to use this facility will have to use
special libraries which offer the calls for communication with this
server. In a microkernel system it is possible to incorporate the
server into the OS without the need for new "system" calls. From the
users point of view this has the advantage, that nothing changes, he
just gets better performance (in terms of more disk space for example).
From the implementors point of view, the microkernel system is faster
adaptable to changes in hardware design.
It has been critized, that AST rejects any improvements to Minix. As he
is interested in the educational value of Minix, I understand his
argument, that he wants to keep the code simple, and don't want to
overload it with features. As an educational tool, Minix is written as
a microkernel system, although it is running on hardware platforms, who
will probably better perform with a monolithic OS. But the area of
network applications is growing and modern OS like Amoeba or Plan 9
cannot be written as monolithic systems. So Minix has been written with
the intention to give students a practical example of a microkernel OS,
to let them play with tasks and messages. It was not the idea to give a
lot of people a cheap, powerful OS for a tenth of the price of SYSV or
BSD implementations.
Resumee: Linux is not better than Minix, or the other way round. They
are different for good reasons.
--
Olaf Schlueter, Sandkuhle 4-6, | olaf@oski.toppoint.de,
2300 Kiel 1, Germany, Toppoint Mailbox e.V. | olaf@tpki.toppoint.de
"When MSDOS was written specifically for the 8088 ..., this was less then
brilliant. Writing an OS only for the 386 in 91 gets you the second 'F'..." AST
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From: cwr@pnet01.cts.com (Will Rose)
Newsgroups: comp.os.minix
Subject: Re: LINUX is obsolete
Date: 1 Feb 92 12:16:12 GMT
Organization: People-Net [pnet01], El Cajon CA
I've used Minix quite a bit on a PC XT, from version 1.2 onwards, and
a couple of points seem worth making. Firstly that I ordered version
1.1 from Prentice Hall, and am devoutly thankful that they delayed my
order until 1.2 was available. The first version of something as
complicated as an OS is only for the dedicated, and that goes for Linux
too I should think.
Secondly Minix has evolved to a reliable OS on its original PC platform,
but is still getting there on eg. the Mac; these things do take time.
Thirdly even (standard) PC 1.5 Minix won't run a lot of current Unix
software. Partly this is a matter of the hardware being too limited,
and partly a matter of Minix being too limited in eg: the tty driver.
(And even this tty driver took a lot of sorting out in the early days).
Fourthly, I bought my XT four years ago - the motherboard was $110,
and memory (falling in price) was $7.00 per 256KB chip. Last autumn
I bought my wife an XT to replace her CP/M word-processor - the m/b
was $50, and memory was $1.50 a chip. This week I replaced a dead
286 board for a friend - the drop-in 16MHz 386SX was $140, and memory
was $40 for 9 x 1MB... If I actually wanted an OS to use today, I
think I'd go with Linux; but if I wanted to learn about OS's, I think
I'd use Minix. It looks as if they both do what they were designed
to do.
Will
cwr@pnet01.cts.com
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Mach/Minix/Linux/Gnu etc.
Date: 1 Feb 92 17:11:03 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
Well, this has been a fun discussion. I am absolutely convinced by
Prof. Tannenbaum that a micro-kernel _is_ the way to go, but the more
I look at the Minix source, the less I believe that it is a
micro-kernel. I would probably not bother porting Linux to the
M68000, but I want more services than Minix can offer.
What about a micro-kernel which is message/syscall compatible with
MACH? It doesn't actually have to do everything that MACH does, like
virtual memory paging -- it just has to _look_ like MACH from the
outside, to fool programs like the future Gnu Unix-emulator, BSD, etc.
This would extend the useful lives of our M68000- or 80286-based
machines for a little longer. In the meantime, I will probably stay
with Minix for my ST rather than switching back to MiNT -- after all,
Minix at least looks like Unix, while MiNT looks like TOS trying to
look like Unix (it has to, to be TOS compatible).
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
#################################################################
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From: gkm@sys6626.bison.mb.ca (greg moeller)
Newsgroups: comp.os.minix
Subject: Minix VS Linux
Date: 2 Feb 92 04:38:14 GMT
Organization: system 6626 BBS, Winnipeg MB
Just wanted to throw in one point about getting Minix because it can run
on just an 8088.
If I were a student with an 8088 and had a choice of buying Minix for
$169, or spending about $140 for a 16 Mhz 386sx motherboard and get Linux
for free, I think I'd get the new motherboard.
Greg
P.S. all in all, I think it depends on what you want to do with the OpSys
that should determine what you get.
--- (greg moeller) a user of sys6626, running waffle 1.64
E-mail: gkm@sys6626.bison.mb.ca
system 6626: 63 point west drive, winnipeg manitoba canada R3T 5G8
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From: ortmann@plains.NoDak.edu (Daniel Ortmann)
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Date: 2 Feb 92 19:42:13 GMT
Organization: North Dakota State University, Fargo, ND
What type of kernal is gnu going to have?
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Newsgroups: comp.os.minix
From: meggin@epas.utoronto.ca (David Megginson)
Subject: Re: Minix VS Linux
Organization: University of Toronto - EPAS
Date: Sun, 2 Feb 1992 20:23:11 GMT
Nntp-Posting-Host: epas.utoronto.ca
In article <14883@plains.NoDak.edu> ortmann@plains.NoDak.edu (Daniel Ortmann) writes:
>What type of kernal is gnu going to have?
Gnu will have a Unix emulator running on top of the Mach kernel. The Unix
emulator is currently in the early stages. There is an information sheet
on the Gnu project at prep.ai.mit.edu.
David
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From: odiug@cip-s08.informatik.rwth-aachen.de (Guido Muesch)
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Date: 4 Feb 92 13:16:26 GMT
Organization: RBI - RWTH Aachen
Nntp-Posting-Host: cip-s08
gkm@sys6626.bison.mb.ca (greg moeller) writes:
>Just wanted to throw in one point about getting Minix because it can run
>on just an 8088.
The 8088 is obsolate. And my opinion is that Minix should only support
the i386 of all intel architectures in the future. It is to much overhead
to support the old 16-bit processors. Minix could be cleaned up easier if
the old 16-bit stuff will be removed.
>If I were a student with an 8088 and had a choice of buying Minix for
>$169, or spending about $140 for a 16 Mhz 386sx motherboard and get Linux
>for free, I think I'd get the new motherboard.
Thats also my reason for suggesting NOT to support the old 16-bit architectures.
People who are willing to pay $169 for Minix-PC can also spend another $140
for a new Motherboard. (If not they still have Linux 8-))
Cheers Guido
>Greg
>P.S. all in all, I think it depends on what you want to do with the OpSys
> that should determine what you get.
>--- (greg moeller) a user of sys6626, running waffle 1.64
>E-mail: gkm@sys6626.bison.mb.ca
>system 6626: 63 point west drive, winnipeg manitoba canada R3T 5G8
--
/\ bitnet: odiug%messua.informatik.rwth-aachen.de@unido.bitnet
/ \ email: odiug@messua.informatik.rwth-aachen.de
__/ \ ________________________________________________________________
\/ snail: Guido Muesch, Ruetscher Str.165/1413, 5100 Aachen
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*** EOOH ***
From: vpaul@nmsu.edu (Vincent J. Paul)
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Summary: rebuttal flame-from-hell
Date: 4 Feb 92 18:55:47 GMT
Organization: New Mexico State University
In article <odiug.697209386@cip-s08>, odiug@cip-s08.informatik.rwth-aachen.de (Guido Muesch) writes:
>
>
> The 8088 is obsolate. And my opinion is that Minix should only support
> the i386 of all intel architectures in the future. It is to much overhead
> to support the old 16-bit processors. Minix could be cleaned up easier if
> the old 16-bit stuff will be removed.
>
> >If I were a student with an 8088 and had a choice of buying Minix for
> >$169, or spending about $140 for a 16 Mhz 386sx motherboard and get Linux
> >for free, I think I'd get the new motherboard.
>
> Thats my reason for suggesting NOT to support the old 16-bit architectures.
> People who are willing to pay $169 for Minix-PC can also spend another $140
> for a new Motherboard. (If not they still have Linux 8-))
>
You missed the point completely, Guido. I'll be generous, though, and
assume it was due to language diffulties. In smaller words, if you
already own an 8088 box (and a lot of people still do) then buying a
new box for $800 is MUCH more expensive than buying a $169 OS that is
compatible. Saying "[spend] $140 on a 386 motherboard and get Linux
for free..." is like saying to Ethiopians "Just buy a plane ticket to
somewhere where there is a food surplus." AST made a few good points
which have been glossed over: with limited budgets (like mine), and
a fixed set of hardware, Minix is much more affordable than Linux.
IF (and only if) that fixed set of hardware jsut HAPPENS to be 386-
based, THEN Linux is a great bargain. Your attitude is much like that
attributed to Marie Antoinette\--"Let them eat cake!" Atari and Mac
owners have the wrong hardware. Let them get the proper one! (Note:
not the proper "ones"--portability, bud, is a GOOD thing.)
And as for that statement, "suggesting NOT to support the
old 16-bit architectures," are you offering to pay for the upgrades?
Somehow I doubt it.
Just for your information (and the world at large) I bought
Minix 1-1/2 years ago, and my XT-clone 5 years ago for $400. Since
then, I've been going to school, not getting rich. I can hardly
afford eating regularly, much less keeping up with Intel's CPU-chip
fashions. If you want a 32-bit Intel-dedicated OS, go get Linux,
and get the hell off this newsgroup. Don't go toasting anyone for
providing, as Andy Tanenbaum REALLY has, a public service. Even
if he doesn't cater to you.
There, I've had my day. Let's call an end to this
controversy, shall we? If you prefer Linux, go hang out with the
Linux crowd over on (I think) alt.linux. Rag on Minix all you
can stand there. Hanging around in comp.os.minix reeks of low
to lowest class. And if anyone was going to convert, they already
would have by now, don't you think? (Really. DON'T you?)
Vince Paul/vpaul@nmsu.edu
-------------------------------------------------------------------------------
Vincent J. Paul | vpaul@nmsu.edu
New Mexico State University | OPR016%BITNET.NMSUVM1
"I take no resposibility for anyone believing anything I say. Even this."
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From: asg@sage.cc.purdue.edu (The Grand Master)
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Date: 6 Feb 92 02:10:58 GMT
Organization: Purdue University Computing Center
In article <1992Feb4.185547.9585@nmsu.edu> vpaul@nmsu.edu (Vincent J. Paul) writes:
}In article <odiug.697209386@cip-s08>, odiug@cip-s08.informatik.rwth-aachen.de (Guido Muesch) writes:
}>
}>
}>
}> >If I were a student with an 8088 and had a choice of buying Minix for
}> >$169, or spending about $140 for a 16 Mhz 386sx motherboard and get Linux
}> >for free, I think I'd get the new motherboard.
}>
}> Thats my reason for suggesting NOT to support the old 16-bit architectures.
}> People who are willing to pay $169 for Minix-PC can also spend another $140
}> for a new Motherboard. (If not they still have Linux 8-))
}>
}You missed the point completely, Guido. I'll be generous, though, and
}assume it was due to language diffulties. In smaller words, if you
This is totally uncalled for - and I think you owe Guido an apology.
Geez - and we (Americans) wonder why we have such a bad reputation
abroad.
}already own an 8088 box (and a lot of people still do) then buying a
}new box for $800 is MUCH more expensive than buying a $169 OS that is
}compatible.
Maybe you are the one who is not understanding. What he is saying is
that you do not NEED to spend $800 on a new system, just $140 for a
386sx motherboard.
}Saying "[spend] $140 on a 386 motherboard and get Linux
}for free..." is like saying to Ethiopians "Just buy a plane ticket to
}somewhere where there is a food surplus."
Not even close. IF SOMEONE CAN AFFORD TO BUY MINIX, THEN THEY CAN OBVIOUSLY
AFFORD TO PUT THAT $169 DOLLARS TOWARDS A 386sx MOTHERBOARD! And *SAVE*
$29 in the process if you find a 386sx motherboard for $140. So your
analogy does not hold - considering that a starving Ethiopian is not
likely to have the money to buy a plane ticket to anywhere.
}AST made a few good points
}which have been glossed over: with limited budgets (like mine), and
}a fixed set of hardware, Minix is much more affordable than Linux.
}IF (and only if) that fixed set of hardware jsut HAPPENS to be 386-
}based, THEN Linux is a great bargain. Your attitude is much like that
}attributed to Marie Antoinette\--"Let them eat cake!" Atari and Mac
}owners have the wrong hardware. Let them get the proper one! (Note:
}not the proper "ones"--portability, bud, is a GOOD thing.)
Portability is both good and bad - the unfortunate thing about portability
is that it does not allow you to take advantage of many hardware-specific
features.
} Just for your information (and the world at large) I bought
}Minix 1-1/2 years ago, and my XT-clone 5 years ago for $400. Since
}then, I've been going to school, not getting rich. I can hardly
}afford eating regularly, much less keeping up with Intel's CPU-chip
}fashions. If you want a 32-bit Intel-dedicated OS, go get Linux,
}and get the hell off this newsgroup. Don't go toasting anyone for
}providing, as Andy Tanenbaum REALLY has, a public service. Even
}if he doesn't cater to you.
Mr. Tanenbaum, though undoubtedly a gifted professor, and undoubtedly
a gifted programmer, is not providing a "PUBLIC SERVICE". MINIX was
written for his students, and AST had the fortune that MINIX caught
on, and has now sold many copies. AST makes money off the deal I am
sure - and if he does not, then I cannot understand why he does not
free the code of copyright, so it can be distributed.
And you might remember that the person who started this thread was
not Guido, nor anyone else in the "Linux camp".
} And if anyone was going to convert, they already
}would have by now, don't you think? (Really. DON'T you?)
}
It really has nothing to do with conversion. Don't get me wrong - I
think MINIX is a brilliant piece of work, and it is certainly well
thought of by some (likely large) segment of the OS-knowledgable
population. But AST attacked Linux for no reason whatsoever. Linus
has created a brilliant piece of work as well - one that incorperates
many of the features that people want which are not readily (or at
all in some cases) available for MINIX. The important thing about Linux
is that it is here, and it works, and its free. There is NO other OS
available (portable or not) that fits the bill that Linux does.
AST's comments were absolutely uncalled for - and his feelings for
those of us out here who would like some common useful features
(like > 64k segments, or job control, or TCP/IP) are readily appearant
from his comment about (note: slightly paraphrased) ".....keeping all those
people who want to turn MINIX into BSD...." off his back. Clearly
he is not in the "Public Service" field.
--
-How long must we fight? How long Courtesy of Bruce Varney
until we can live in peace. asg@sage.cc.purdue.edu
-Until the madmen are dead my son,
Or until they realize that they cannot count on us to do nothing
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From: stolk@fwi.uva.nl (Bram)
Newsgroups: comp.os.minix
Subject: 'folks with enough money' (was: LINUX-MINIX)
Date: 3 Feb 92 11:43:17 GMT
Organization: FWI, University of Amsterdam
Nntp-Posting-Host: irwin.fwi.uva.nl
Hi,
In one of the previous articles, ast wrote:
> Just for the record, as of about 1 year ago, there were two
>versions, one for the PC (360K diskettes) and one for the 286/386 (1.2M).
>The PC version was outselling the 286/386 version by 2 to 1. I don't have
>figures, but my guess is that the fraction of the 60 million existing PCs that
>are 386/486 machines as opposed to 8088/286/680x0 etc is small. Among students
>it is even smaller. Making software free, but only for folks with enough money
>to buy first class hardware is an interesting concept.
Hmm... can I do a little math here?
define: configuration 1: 8088 PC, 2 floppydrives, monitor.
configuration 2: 386 AT, 2 floppydrives, monitor.
let A be the price of config. 1 at the time of
MINIX' conception.
Let B be the price of config. 2 at the time of
LINUX' conception.
Question:
What are the chances of 'A >= B' being true?
My answer:
I would say, better than average.
The point I am trying to make is: nowadays, students buy 386s.
Not because students are rich, but because 386s from Taiwan
come VERY cheap. (Many of my fellow students have 386s)
So 'the folks with enough money' bit is kinda naive. IBM's 8088s
used to sell at the price of small cars, in the old days.
I would favor LINUX, even if it were only for the lack of
proper object files in MINIX.
Bram Stolk
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From: cwr@pnet01.cts.com (Will Rose)
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Date: 3 Feb 92 14:16:11 GMT
Organization: People-Net [pnet01], El Cajon CA
kevin@taronga.taronga.com (Kevin Brown) writes:
>It has been brought to my attention that my last posting was exceedingly
>harsh. Having reread it, I'm inclined to agree.
Didn't seem so to me - or is everyone else getting much more tactful in
the 'kinder, gentler' 1990s?
>Despite that, Minix is quite usable in many ways as a personal operating
>system, i.e. one where there is usually only one person logged into the
>system.
.... lines omitted
>However, as a *multiuser* operating system, i.e. an operating system designed
>to efficiently meet the needs of multiple users simultaneously while also
>performing batch operations, Minix is lacking, as far as I'm concerned.
>The main reason, of course, is the single-threaded file system (hereafter,
>STFS).
In fact, Minix has noticeable problems even as a *single-user* system; such
a user is likely to be developing code in an 'edit - compile - test' cycle,
and on a multitasking machine compilation can conveniently take place in
the background using multiple processes. Given the small amount of memory
on the early Minix machines, it probably wasn't practical to edit in the
foreground during a compile; but a low-end XT such as mine can now put the
ram-disk in expanded memory and have 500KB free after the OS is loaded.
However, editing during a compile is still totally impractical; the standard
1.5 scheduler can't cope, and keyboard response time is both long (seconds)
and variable. The fix is simple, use Kai-Uwe Bloem's (spelling ?) patch.
KuB's scheduler algorithm isn't the last word in sophistication, and the code
change is a small one, yet it is extremely effective. I don't understand
why the original scheduler lasted so long.
Broadly speaking, when porting programs to Minix, or writing them from
scratch, the main problems are not details of kernel implementation but things
that are simply missing, such as non-blocking reads or SIGHUP. If a program
is to be used on the majority of Minix systems, then it must be written for
the lowest common denominator ie: the standard current release, and this has
significant limitations. Only after these are overcome does the lack of
memory space, or lack of filesystem performance, become important. (It
is quite possible that many of these problems will be fixed in 1.6, but
that still lies in the future. By the time it arrives, the goalposts will
have moved again... )
>Someone, either here on this newsgroup or over on alt.os.linux, made a
>very valid observation: the cost of a 16 MHz 386SX system is about $140
>more than a comparably equipped (in terms of RAM size, display technology,
>hard drive space, etc.) 8088 system. Minix is $169. In economic terms,
>Linux wins if you have to buy Minix.
This may have been drawn from a comment of mine, concerning the recent
replacement of a dead 286 motherboard with a 386SX; it was part of an
example of just how fast hardware prices are falling. The *board* price
was $140, ie: $90 more than an XT board. Memory is about the same price
for both boards, but obviously the system price for the 386 will tend to be
higher with the use of faster, larger disk drives, more memory, and so on.
In the last year PH has started marketing Minix as a small general-purpose/
training Unix, but if Minix 2.0 isn't released for another year, I think it
will become strictly an adjunct to a successful textbook. It won't run
enough of the then-available PD code to be useful for anything else, since
such code will mostly require gcc and megabytes of memory, implying at least
a 386. (I'm assuming that the cheapest hardware will still be Intel/ISA bus).
Linux seems well-placed to pick up on this wave; whether it will also make
inroads into academe via easy FTP availability (a version of 'OS Design and
Implementation' without Minix is coincidentally in hand) remains to be seen.
Will Rose
cwr@pnet01.cts.com
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From: kevin@taronga.taronga.com
Newsgroups: comp.os.minix
Subject: Re: Minix VS Linux
Date: 4 Feb 92 07:56:04 GMT
Organization: University of Houston
In article <1992Feb03.141611.6995@crash.cts.com> cwr@pnet01.cts.com (Will Rose) writes:
>
>kevin@taronga.taronga.com (Kevin Brown) writes:
>
>>It has been brought to my attention that my last posting was exceedingly
>>harsh. Having reread it, I'm inclined to agree.
>
>Didn't seem so to me - or is everyone else getting much more tactful in
>the 'kinder, gentler' 1990s?
Guess it depends on whether or not you agree with what I had to say. ;-)
Some people read other people's postings with an implied "IMHO". Others
don't. Those that don't will probably think of that posting as exceedingly
harsh. Since I try to be as explicit as possible, I would say I didn't
put enough "IMHO"s in.
>>Despite that, Minix is quite usable in many ways as a personal operating
>>system, i.e. one where there is usually only one person logged into the
>>system.
>... lines omitted
>>However, as a *multiuser* operating system, i.e. an operating system designed
>>to efficiently meet the needs of multiple users simultaneously while also
>>performing batch operations, Minix is lacking, as far as I'm concerned.
>>The main reason, of course, is the single-threaded file system (hereafter,
>>STFS).
>
>In fact, Minix has noticeable problems even as a *single-user* system; such
>a user is likely to be developing code in an 'edit - compile - test' cycle,
>and on a multitasking machine compilation can conveniently take place in
>the background using multiple processes. Given the small amount of memory
>on the early Minix machines, it probably wasn't practical to edit in the
>foreground during a compile; but a low-end XT such as mine can now put the
>ram-disk in expanded memory and have 500KB free after the OS is loaded.
>However, editing during a compile is still totally impractical; the standard
>1.5 scheduler can't cope, and keyboard response time is both long (seconds)
>and variable. The fix is simple, use Kai-Uwe Bloem's (spelling ?) patch.
>KuB's scheduler algorithm isn't the last word in sophistication, and the code
>change is a small one, yet it is extremely effective. I don't understand
>why the original scheduler lasted so long.
I agree wholeheartedly. In fact, Bruce Evans sent me a very simple patch
that gives an I/O bound process like an editor effectively infinite
priority: it causes the process that's being readied (in the ready()
routine in proc.c) to be added to the beginning of the process queue
instead of the end. This fixes the problem for sure, but it causes
CPU bound processes to suffer rather badly in the face of I/O bound
processes.
>Broadly speaking, when porting programs to Minix, or writing them from
>scratch, the main problems are not details of kernel implementation but things
>that are simply missing, such as non-blocking reads or SIGHUP.
I've had the SIGHUP problem solved on my system for some time, but I've
got weird problems with the signal handling as relates to process groups
and signalling a parent process in a process group before signalling the
child. Causes very strange things to happen (like the FS to restart!
You get the message "executing in protected mode" as a result of killing
a parent process before killing the child process). This is the primary
reason I don't have UUCP going on my system already. I don't trust it
enough to handle a UUCP connection going away (dropping carrier) in the
middle of a transfer.
>If a program
>is to be used on the majority of Minix systems, then it must be written for
>the lowest common denominator ie: the standard current release, and this has
>significant limitations. Only after these are overcome does the lack of
>memory space, or lack of filesystem performance, become important. (It
>is quite possible that many of these problems will be fixed in 1.6, but
>that still lies in the future. By the time it arrives, the goalposts will
>have moved again... )
What he said. :-)
>>Someone, either here on this newsgroup or over on alt.os.linux, made a
>>very valid observation: the cost of a 16 MHz 386SX system is about $140
>>more than a comparably equipped (in terms of RAM size, display technology,
>>hard drive space, etc.) 8088 system. Minix is $169. In economic terms,
>>Linux wins if you have to buy Minix.
>
>This may have been drawn from a comment of mine, concerning the recent
>replacement of a dead 286 motherboard with a 386SX; it was part of an
>example of just how fast hardware prices are falling. The *board* price
>was $140, ie: $90 more than an XT board. Memory is about the same price
>for both boards, but obviously the system price for the 386 will tend to be
>higher with the use of faster, larger disk drives, more memory, and so on.
Right. The only time the architecture bites you is when your applications
are larger as a result of using a 32-bit memory model, though. So while
you tend to use faster and larger disk drives, more memory, etc. for the
386, that's because you *can* more than anything else. The architecture
supports it. I figure the larger and faster hard drives come as a result
of having more memory to stuff programs into. :-)
If the price difference is only $90, then the 386SX *definitely* wins. For
the $80 I save in buying a 386SX and getting Linux, I can get another 50
meg of hard drive space, or perhaps even more, depending on where on the
price/capacity curve I am.
>In the last year PH has started marketing Minix as a small general-purpose/
>training Unix, but if Minix 2.0 isn't released for another year, I think it
>will become strictly an adjunct to a successful textbook. It won't run
>enough of the then-available PD code to be useful for anything else, since
>such code will mostly require gcc and megabytes of memory, implying at least
>a 386. (I'm assuming that the cheapest hardware will still be Intel/ISA bus).
I don't know. While I agree that many of the applications will be too
large, there's something to be said for small, efficient programs, and
something to be said against large, baroque programs. Having lots of
features isn't necessarily a good thing, despite what the marketers
might tell you.
>Linux seems well-placed to pick up on this wave; whether it will also make
>inroads into academe via easy FTP availability (a version of 'OS Design and
>Implementation' without Minix is coincidentally in hand) remains to be seen.
Maybe we can get Linus to write a book on operating systems. :-) :-)
>Will Rose
>cwr@pnet01.cts.com
Kevin Brown
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*** EOOH ***
From: peter@ferranti.com (peter da silva)
Newsgroups: comp.os.minix
Subject: What good does this war do? (Re: LINUX is obsolete)
Date: 3 Feb 92 16:37:24 GMT
Organization: Xenix Support, FICC
Will you quit flaming each other?
I mean, linux is designed to provide a reasonably high performance environment
on a hardware platform crippled by years of backwards-compatible kludges. Minix
is designed as a teaching tool. Neither is that good at doing the other's job,
and why should they? The fact that Minix runs out of steam quickly (and it
does) isn't a problem in its chosen mileau. It's sure better than the TOY
operating system. The fact that Linux isn't transportable beyond the 386/AT
platform isn't a problem when there are millions of them out there (and quite
cheap: you can get a 386/SX for well under $1000).
A monolithic kernel is easy enough to build that it's worth doing it if it gets
a system out the door early. Think of it as a performance hack for programmer
time. The API is portable. You can replace the kernel with a microkernel
design (and MINIX isn't the be-all and end-all of microkernel designs either:
even for low end PCs... look at AmigaOS) without disturbing the applications.
That's the whole point of a portable API in the first place.
Microkernels are definitely a better design for many tasks. I takes more
work to make them efficient, so a simpler design that doesn't take advantage
of the microkernel in any real way is worth doing for pedagogical reasons.
Think of it as a performance hack for student time. The design is still good
and when you can get an API to the microkernel interface you can get VERY
impressive performance (thousands of context switches per second on an 8
MHz 68000).
--
-- Peter da Silva, Ferranti International Controls Corporation
-- Sugar Land, TX 77487-5012; +1 713 274 5180
-- "Have you hugged your wolf today?"
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Unhappy campers
Date: 3 Feb 92 22:46:40 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
I've been getting a bit of mail lately from unhappy campers. (Actually 10
messages from the 43,000 readers may seem like a lot, but it is not really.)
There seem to be three sticking points:
1. Monolithic kernels are just as good as microkernels
2. Portability isn't so important
3. Software ought to be free
If people want to have a serious discussion of microkernels vs. monolithic
kernels, fine. We can do that in comp.os.research. But please don't sound off
if you have no idea of what you are talking about. I have helped design
and implement 3 operating systems, one monolithic and two micro, and have
studied many others in detail. Many of the arguments offered are nonstarters
(e.g., microkernels are no good because you can't do paging in user space--
except that Mach DOES do paging in user space).
If you don't know much about microkernels vs. monolithic kernels, there is
some useful information in a paper I coauthored with Fred Douglis, Frans
Kaashoek and John Ousterhout in the Dec. 1991 issue of COMPUTING SYSTEMS, the
USENIX journal). If you don't have that journal, you can FTP the paper from
ftp.cs.vu.nl (192.31.231.42) in directory amoeba/papers as comp_sys.tex.Z
(compressed TeX source) or comp_sys.ps.Z (compressed PostScript). The paper
gives actual performance measurements and supports Rick Rashid's conclusion that
microkernel based systems are just as efficient as monolithic kernels.
As to portability, there is hardly any serious discussion possible any more.
UNIX has been ported to everything from PCs to Crays. Writing a portable
OS is not much harder than a nonportable one, and all systems should be
written with portability in mind these days. Surely Linus' OS professor
pointed this out. Making OS code portable is not something I invented in 1987.
While most people can talk rationally about kernel design and portability,
the issue of free-ness is 100% emotional. You wouldn't believe how much
[expletive deleted] I have gotten lately about MINIX not being free. MINIX
costs $169, but the license allows making two backup copies, so the effective
price can be under $60. Furthermore, professors may make UNLIMITED copies
for their students. Coherent is $99. FSF charges >$100 for the tape its "free"
software comes on if you don't have Internet access, and I have never heard
anyone complain. 4.4 BSD is $800. I don't really believe money is the issue.
Besides, probably most of the people reading this group already have it.
A point which I don't think everyone appreciates is that making something
available by FTP is not necessarily the way to provide the widest distribution.
The Internet is still a highly elite group. Most computer users are NOT on it.
It is my understanding from PH that the country where MINIX is most widely used
is Germany, not the U.S., mostly because one of the (commercial) German
computer magazines has been actively pushing it. MINIX is also widely used in
Eastern Europe, Japan, Israel, South America, etc. Most of these people would
never have gotten it if there hadn't been a company selling it.
Getting back to what "free" means, what about free source code? Coherent
is binary only, but MINIX has source code, just as LINUX does. You can change
it any way you want, and post the changes here. People have been doing that
for 5 years without problems. I have been giving free updates for years, too.
I think the real issue is something else. I've been repeatedly offered virtual
memory, paging, symbolic links, window systems, and all manner of features. I
have usually declined because I am still trying to keep the system simple
enough for students to understand. You can put all this stuff in your version,
but I won't put it in mine. I think it is this point which irks the people who
say "MINIX is not free," not the $60.
An interesting question is whether Linus is willing to let LINUX become "free"
of his control. May people modify it (ruin it?) and sell it? Remember the
hundreds of messages with subject "Re: Your software sold for money" when it
was discovered the MINIX Centre in England was selling diskettes with news
postings, more or less at cost?
Suppose Fred van Kempen returns from the dead and wants to take over, creating
Fred's LINUX and Linus' LINUX, both useful but different. Is that ok? The
test comes when a sizable group of people want to evolve LINUX in a way Linus
does not want. Until that actually happens the point is moot, however.
If you like Linus' philosophy rather than mine, by all means, follow him, but
please don't claim that you're doing this because LINUX is "free." Just
say that you want a system with lots of bells and whistles. Fine. Your choice.
I have no argument with that. Just tell the truth.
As an aside, for those folks who don't read news headers, Linus is in Finland
and I am in The Netherlands. Are we reaching a situation where another
critical industry, free software, that had been totally dominated by the U.S.
is being taken over by the foreign competition? Will we soon see
President Bush coming to Europe with Richard Stallman and Rick Rashid
in tow, demanding that Europe import more American free software?
Andy Tanenbaum (ast@cs.vu.nl)
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From: meulenbr@ce.philips.nl (Frans Meulenbroeks)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 4 Feb 92 17:21:31 GMT
Organization: Philips Consumer Electronics, Eindhoven
First of all I want to say, that I like to support the idea of Andy to
keep minix small. If you want something large go for GNU.
I'm also against featurism.
However, undoubtly my wanted set of features differs from Andy's set.
Therefore what I would like to see, is something which allows it to
add features easily. If for instance device drivers are loadable, or
easier to add as they are now, then the core and some drivers can be
the standard PH minix. If people want to add something, then it is nice
to have a mechanism with which you can do so, without having to meddle
with things like fs/table.c kernel/table.c include/minix/config.h (for
NR_TASKS) etc.
ast@cs.vu.nl (Andy Tanenbaum) writes:
>Suppose Fred van Kempen returns from the dead and wants to take over, creating
Just a remark for the readers. As far as I know Fred is not physically dead.
If english is not your native language (just like mine) you might
conclude otherwise from ast's words. Fred is only electronically dead.
--
Frans Meulenbroeks (meulenbr@prl.philips.nl)
Philips Research Laboratories
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From: jonathan@ukmug.uk.mugnet.org (Jonathan Allen)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 11:43:05 GMT
Organization: MUGNET UK Backbone (UKMUG)
In article <1992Feb4.172131.18145@philce.ce.philips.nl>, meulenbr@ce.philips.nl (Frans Meulenbroeks) wrote:
> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>>Suppose Fred van Kempen returns from the dead and wants to take over, creating
>
> Just a remark for the readers. As far as I know Fred is not physically dead.
> If english is not your native language (just like mine) you might
> conclude otherwise from ast's words. Fred is only electronically dead.
Well, just you wait and see :-) !!!
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From: meggin@epas.utoronto.ca (David Megginson)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 4 Feb 92 20:17:22 GMT
Organization: University of Toronto - EPAS
Nntp-Posting-Host: epas.utoronto.ca
In article <12667@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>As an aside, for those folks who don't read news headers, Linus is in Finland
>and I am in The Netherlands. Are we reaching a situation where another
>critical industry, free software, that had been totally dominated by the U.S.
>is being taken over by the foreign competition? Will we soon see
>President Bush coming to Europe with Richard Stallman and Rick Rashid
>in tow, demanding that Europe import more American free software?
Actually, the U.S. is more likely to have you arrested for selling
restricted software to unfriendly powers (not that anyone in the
C.I.S. can afford software this winter -- they're probably burning
their PCs for heat). I remember that they jailed some poor computer
vendor in the U.K. a couple of years ago.
Seriously, you must have run into this problem with crypt and Minix
distribution in and out of the U.S.
David
#################################################################
David Megginson meggin@epas.utoronto.ca
Centre for Medieval Studies david@doe.utoronto.ca
University of Toronto 39 Queen's Park Cr. E.
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Newsgroups: comp.os.minix
From: jkp@cs.HUT.FI (Jyrki Kuoppala)
Subject: Re: Unhappy campers
In-Reply-To: meggin@epas.utoronto.ca (David Megginson)
Nntp-Posting-Host: sauna.cs.hut.fi
Reply-To: jkp@cs.HUT.FI (Jyrki Kuoppala)
Organization: Helsinki University of Technology, Finland
Date: Wed, 5 Feb 1992 15:47:26 GMT
In article <1992Feb4.201722.20620@epas.toronto.edu>, meggin@epas (David Megginson) writes:
>Actually, the U.S. is more likely to have you arrested for selling
>restricted software to unfriendly powers (not that anyone in the
>C.I.S. can afford software this winter -- they're probably burning
>their PCs for heat). I remember that they jailed some poor computer
>vendor in the U.K. a couple of years ago.
Around here a few years ago they had a trial against a couple of guys
who sold old VAXes to the Soviet Union. They were charged with
treason because they were breaking some export rules. They weren't
convicted, though, I think it was something about the export rules not
being a law in Finland.
For some reason the U.S. troups didn't come to Finland to kill a few
thousand people and take these guys to USA for a trial like they did
with another person in another country.
//Jyrki
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 11:03:51 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <1992Feb5.154726.983@nntp.hut.fi> jkp@cs.HUT.FI (Jyrki Kuoppala) writes:
>
>Around here a few years ago they had a trial against a couple of guys
>who sold old VAXes to the Soviet Union.
In their book, Cyberpunk, Katie Hafner and John Markoff report that a group
of hackers tried to sell MINIX to the KGB claiming it was the VMS source
code. The KGB didn't buy.
Andy Tanenbaum (ast@cs.vu.nl)
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From: james@fiskville.mc.utexas.edu (James Hammett)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 8 Feb 92 02:18:28 GMT
Reply-To: james@fiskville.mc.utexas.edu (James Hammett)
Organization: The University of Texas at Austin
From what little I understand, the reason Minix needs to use a second
class encryptor for its passwd file is because of the export restrictions.
You can't export or transmit the algorhthym (sp).
James
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From: fnf@fishpond.uucp (Fred Fish)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 4 Feb 92 20:57:40 GMT
Organization: Amiga Library Distribution Services
In article <12667@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>While most people can talk rationally about kernel design and portability,
>the issue of free-ness is 100% emotional. You wouldn't believe how much
>[expletive deleted] I have gotten lately about MINIX not being free. MINIX
>costs $169, but the license allows making two backup copies, so the effective
>price can be under $60. Furthermore, professors may make UNLIMITED copies
>for their students. Coherent is $99. FSF charges >$100 for the tape its "free"
>software comes on if you don't have Internet access, and I have never heard
>anyone complain. 4.4 BSD is $800. I don't really believe money is the issue.
>Besides, probably most of the people reading this group already have it.
The distribution cost is not the problem. As you've noted, nobody complains
about the FSF's distribution fee being too high. The problem, as I see it,
is that there is only one legal source for for the software for people that
simply want a working release. And from watching the minix group since
minix first became available, my impression is that nobody enjoys dealing
with PH for a whole host of reasons.
>I think the real issue is something else. I've been repeatedly offered virtual
>memory, paging, symbolic links, window systems, and all manner of features. I
>have usually declined because I am still trying to keep the system simple
>enough for students to understand. You can put all this stuff in your version,
>but I won't put it in mine. I think it is this point which irks the people who
>say "MINIX is not free," not the $60.
If PH was not granted a monopoly on distribution, it would have been possible
for all of the interested minix hackers to organize and set up a group that
was dedicated to producing enhanced-minix. This aim of this group could have
been to produce a single, supported version of minix with all of the commonly
requested enhancements. This would have allowed minix to evolve in much the
same way that gcc has evolved over the last few years. Sure there are variant
versions of gcc, but most of the really good enhancements, bug fixes, etc
are eventually folded back into a master source base that future distributions
derive from. Thus you would have been left in peace to continue your tight
control over the educational version of minix, and everyone else that wanted
more than an educational tool could put their energies into enhanced-minx.
The primary reason I've never gotten into using minix, after the initial
excitement of hearing about it's availability way back when, is that I have
no interest in trying to apply random patches from all over the place, sort
out the problems, and eventually end up with a system that does what I want
it to, but which I can't pass on to anyone else.
>The
>test comes when a sizable group of people want to evolve LINUX in a way Linus
>does not want. Until that actually happens the point is moot, however.
Where is the sizeable group of people that want to evolve gcc in a way that
rms/FSF does not approve of?
Where is the sizeable group of people that want to evolve emacs in a way that
rms/FSF doesn't approve of?
I'd say that if the primary maintainers of a large piece of useful, freely
redistributable, software are at all responsive to incorporating useful
enhancements and acting as the central repository and clearing house for
the software, then these splinter groups simply do not have sufficient
motivation to form. Having a single source for the software, and having
the primary maintainer(s) be unresponsive to the desires of a large group
of users, is the catalyst that causes these sorts of pressures; not the
freedom of the software.
-Fred
--
|\/ o\ Fred Fish, 1835 E. Belmont Drive, Tempe, AZ 85284, USA
|/\__/ 1-602-491-0048 {asuvax,mcdphx,cygint,amix}!fishpond!fnf
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From: vladimir@Eng.Sun.COM (Vladimir Ivanovic)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 5 Feb 92 04:34:18 GMT
Organization: Sun Microsystems, Inc.
NNTP-Posting-Host: ronnie
In-reply-to: fnf@fishpond.uucp's message of 4 Feb 92 20:57:40 GMT
>>>>> On 4 Feb 92 20:57:40 GMT, fnf@fishpond.uucp (Fred Fish) said:
fnf> If PH was not granted a monopoly on distribution, it would have been
fnf> possible for all of the interested minix hackers to organize and set
fnf> up a group that was dedicated to producing enhanced-minix. This aim
fnf> of this group could have been to produce a single, supported version
fnf> of minix with all of the commonly requested enhancements. This would
fnf> have allowed minix to evolve in much the same way that gcc has evolved
fnf> over the last few years. Sure there are variant versions of gcc, but
fnf> most of the really good enhancements, bug fixes, etc are eventually
fnf> folded back into a master source base that future distributions derive
fnf> from. Thus you would have been left in peace to continue your tight
fnf> control over the educational version of minix, and everyone else that
fnf> wanted more than an educational tool could put their energies into
fnf> enhanced-minx.
I don't get it. What's preventing people from doing this? The quoted
paragraph doesn't give any reasons for its assertions.
-- Vladimir
--
Vladimir G. Ivanovic Sun Microsystems, Inc
(415) 336-2315 MTV12-33
vladimir@Eng.Sun.COM 2550 Garcia Ave.
{decwrl,hplabs,ucbvax}!sun!Eng!vladimir Mountain View, CA 94043-1100
Disclaimer: I speak for myself.
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From: mitchell@mdd.comm.mot.com (Bill Mitchell)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 5 Feb 92 15:09:12 GMT
Reply-To: mitchell@mdd.comm.mot.com (Bill Mitchell)
Organization: Motorola, Mobile Data Division - Seattle, WA
Bcc: mitchell
in comp.os.minix, vladimir@Eng.Sun.COM (Vladimir Ivanovic) said:
>>>>>> On 4 Feb 92 20:57:40 GMT, fnf@fishpond.uucp (Fred Fish) said:
>
>fnf> If PH was not granted a monopoly on distribution, it would have been
>fnf> possible for all of the interested minix hackers to organize and set
>fnf> up a group that was dedicated to producing enhanced-minix. This aim
>fnf> of this group could have been to produce a single, supported version
>fnf> of minix with all of the commonly requested enhancements. This would
>fnf> have allowed minix to evolve in much the same way that gcc has evolved
>fnf> over the last few years. Sure there are variant versions of gcc, but
>fnf> most of the really good enhancements, bug fixes, etc are eventually
>fnf> folded back into a master source base that future distributions derive
>fnf> from. Thus you would have been left in peace to continue your tight
>fnf> control over the educational version of minix, and everyone else that
>fnf> wanted more than an educational tool could put their energies into
>fnf> enhanced-minx.
>
>I don't get it. What's preventing people from doing this? The quoted
>paragraph doesn't give any reasons for its assertions.
>
As I understand it PH takes the position that the copyright must be observed,
and that distribution of modified copies of their copyrighted code is in
violation of the copyright. I think that they are required to defend the
copyright against such violations if they want it to remain legally valid.
Diffs against the baseline are allowed. But diffs have to be applied in strict
order. This would be difficult to administer in a tight-knit organization
with well defined distribution channels. In net.anarchy it's all but
unworkable.
The fact that the Minix-386 variant of PC Minix 1.5 has managed to remain
stable as a set of diffs suprises me. I recall that the NLMUG Minix variant
was distributed as modified baseline code instead of as diffs, and that PH
copyright lawyers put a stop to that.
Or do I have it wrong?
--
mitchell@mdd.comm.mot.com (Bill Mitchell)
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From: fnf@fishpond.uucp (Fred Fish)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 5 Feb 92 15:33:33 GMT
Organization: Amiga Library Distribution Services
In article <VLADIMIR.92Feb4203418@ronnie.Eng.Sun.COM> vladimir@Eng.Sun.COM (Vladimir Ivanovic) writes:
>>>>>> On 4 Feb 92 20:57:40 GMT, fnf@fishpond.uucp (Fred Fish) said:
>fnf> If PH was not granted a monopoly on distribution, it would have been
>fnf> possible for all of the interested minix hackers to organize and set
>
>I don't get it. What's preventing people from doing this? The quoted
>paragraph doesn't give any reasons for its assertions.
My understanding is that PH is the only one that is allowed to distribute
a complete minix distribution. All others are restricted to the "2 copy
limit" or by the educational provision for classroom use.
There is apparently no place where I can send a check for $50 - $150 and
receive a complete, ready to install, copy of an enhanced minix that has
most of the common enhancements that are floating around as diff kits,
already installed and tested. When I run into a problem, I can't post
a message saying that eminix version 15.4 does mumble-foo when it should
do mumble-bar, and expect other people to be easily able to reproduce the
problem. Except for people that are running strictly vanilla minix as
received from PH, I doubt that there are any two minix sites anywhere
in the world, that are not directly in touch with each other, that are
running the same set of binaries. This is bug heaven, and a maintenance
nightmare.
If I'm wrong, and there is such a place to get a full 32 bit minix with
VM, hardware supported memory protection, and other assorted enhancements
such as GNU gcc, g++, emacs, etc, with full sources and binaries for the
entire system, preferably for an Amiga 3000, then please tell me. Directions
that go "well first order minix X.X from PH, and then apply patch kit
xxx from ftp site yyy and patch kit zzz from ftp site kkk, and write to
John Doe for his patch kit www, and pick up patch kit ddd from the
minix usenet archives" will be cheerfully ignored.
-Fred
--
|\/ o\ Fred Fish, 1835 E. Belmont Drive, Tempe, AZ 85284, USA
|/\__/ 1-602-491-0048 {asuvax,mcdphx,cygint,amix}!fishpond!fnf
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From: al@escom.com (Al Donaldson)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 14:53:21 GMT
Reply-To: al@escom.COM (Al Donaldson)
Organization: ESCOM Corp., Oakton VA (USA)
In article <207@fishpond.uucp> fnf@fishpond.uucp (Fred Fish) writes:
>My understanding is that PH is the only one that is allowed to distribute
>a complete minix distribution.
Fred,
To the best of my knowledge, PH has no such restriction. In fact,
as of a year ago, PH had an active program to license MINIX to anyone
who wants to use it for whatever purpose. This specifically includes
building variants of the MINIX system such as "enhanced" MINIX.
>There is apparently no place where I can send a check for $50 - $150 and
>receive a complete, ready to install, copy of an enhanced minix that has
>most of the common enhancements that are floating around as diff kits,
>already installed and tested.
Although I didn't explore this specifically, I saw nothing that would
preclude someone or some company from signing a license agreement with PH,
building an "enhanced" version of MINIX, and then selling as many as
the market will bear. The only rule is that this licensee (Company X)
would have to behave like a business: report each sale and collect a
license fee.
The license fees depend upon the quantity Company X believes can be sold,
and require some amount of prepayment. License fees appear to be fairly
reasonable, for example, perhaps US $50 at quantity 1000. But for this
license fee, Company X must duplicate its own diskettes and produce its own
release notes. And answer its own phones, and handle customer gripes, and
strike its own licensing agreements with the individuals who wrote the
various add-on packages that make up eminix. And so on..
>If I'm wrong, and there is such a place to get a full 32 bit minix with
>VM, hardware supported memory protection, and other assorted enhancements
>such as GNU gcc, g++, emacs, etc, with full sources and binaries for the
>entire system, preferably for an Amiga 3000, then please tell me.
I don't know of anyone who sells this, but that's not PH's fault..
Al
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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 5 Feb 92 23:23:26 GMT
Organization: Fac. Wiskunde & Informatica, Vrije Universiteit, Amsterdam
In article <205@fishpond.uucp> fnf@fishpond.uucp (Fred Fish) writes:
>If PH was not granted a monopoly on distribution, it would have been possible
>for all of the interested minix hackers to organize and set up a group that
>was dedicated to producing enhanced-minix. This aim of this group could have
>been to produce a single, supported version of minix with all of the commonly
>requested enhancements. This would have allowed minix to evolve in much the
>same way that gcc has evolved over the last few years.
This IS possible. If a group of people wants to do this, that is fine.
I think co-ordinating 1000 prima donnas living all over the world will be
as easy as herding cats, but there is no legal problem. When a new release
is ready, just make a diff listing against 1.5 and post it or make it FTPable.
While this will require some work on the part of the users to install it,
it isn't that much work. Besides, I have shell scripts to make the diffs
and install them. This is what Fred van Kempen was doing. What he did wrong
was insist on the right to publish the new version, rather than diffs against
the PH baseline. That cuts PH out of the loop, which, not surprisingly, they
weren't wild about. If people still want to do this, go ahead.
Of course, I am not necessarily going to put any of these changes in my version,
so there is some work keeping the official and enhanced ones in sync, but I
am willing to co-operate to minimize work. I did this for a long time with
Bruce Evans and Frans Meulenbroeks.
If Linus wants to keep control of the official version, and a group of eager
beavers want to go off in a different direction, the same problem arises.
I don't think the copyright issue is really the problem. The problem is
co-ordinating things. Projects like GNU, MINIX, or LINUX only hold together
if one person is in charge. During the 1970s, when structured programming
was introduced, Harlan Mills pointed out that the programming team should
be organized like a surgical team--one surgeon and his or her assistants,
not like a hog butchering team--give everybody an axe and let them chop away.
Anyone who says you can have a lot of widely dispersed people hack away on
a complicated piece of code and avoid total anarchy has never managed a
software project.
>Where is the sizeable group of people that want to evolve gcc in a way that
>rms/FSF does not approve of?
A compiler is not something people have much emotional attachment to. If
the language to be compiled is a given (e.g., an ANSI standard), there isn't
much room for people to invent new features. An operating system has unlimited
opportunity for people to implement their own favorite features.
Andy Tanenbaum (ast@cs.vu.nl)
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From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 10:33:31 GMT
Organization: University of Helsinki
In article <12746@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>If Linus wants to keep control of the official version, and a group of eager
>beavers want to go off in a different direction, the same problem arises.
This is the second time I've seen this "accusation" from ast, who feels
pretty good about commenting on a kernel he probably haven't even seen.
Or at least he hasn't asked me, or even read alt.os.linux about this.
Just so that nobody takes his guess for the full thruth, here's my
standing on "keeping control", in 2 words (three?):
I won't.
The only control I've effectively been keeping on linux is that I know
it better than anybody else, and I've made my changes available to
ftp-sites etc. Those have become effectively official releases, and I
don't expect this to change for some time: not because I feel I have
some moral right to it, but because I haven't heard too many complaints,
and it will be a couple of months before I expect to find people who
have the same "feel" for what happens in the kernel. (Well, maybe
people are getting there: tytso certainly made some heavy changes even
to 0.10, and others have hacked it as well)
In fact I have sent out feelers about some "linux-kernel" mailing list
which would make the decisions about releases, as I expect I cannot
fully support all the features that will /have/ to be added: SCSI etc,
that I don't have the hardware for. The response has been non-existant:
people don't seem to be that eager to change yet. (well, one person
felt I should ask around for donations so that I could support it - and
if anybody has interesting hardware lying around, I'd be happy to accept
it :)
The only thing the copyright forbids (and I feel this is eminently
reasonable) is that other people start making money off it, and don't
make source available etc... This may not be a question of logic, but
I'd feel very bad if someone could just sell my work for money, when I
made it available expressly so that people could play around with a
personal project. I think most people see my point.
That aside, if Fred van Kempen wanted to make a super-linux, he's quite
wellcome. He won't be able to make much money on it (distribution fee
only), and I don't think it's that good an idea to split linux up, but I
wouldn't want to stop him even if the copyright let me.
>I don't think the copyright issue is really the problem. The problem is
>co-ordinating things. Projects like GNU, MINIX, or LINUX only hold together
>if one person is in charge.
Yes, coordination is a big problem, and I don't think linux will move
away from me as "head surgeon" for some time, partly because most people
understand about these problems. But copyright /is/ an issue: if people
feel I do a bad job, they can do it themselves. Likewise with gcc. The
minix copyright, however, means that if someone feels he could make a
better minix, he either has to make patches (which aren't that great
whatever you say about them) or start off from scratch (and be attacked
because you have other ideals).
Patches aren't much fun to distribute: I haven't made cdiffs for a
single version of linux yet (I expect this to change: soon the patches
will be so much smaller than the kernel that making both patches and a
complete version available is a good idea - note that I'd still make the
whole version available too). Patches upon patches are simply
impractical, especially for people that may do changes themselves.
>>Where is the sizeable group of people that want to evolve gcc in a way that
>>rms/FSF does not approve of?
>A compiler is not something people have much emotional attachment to. If
>the language to be compiled is a given (e.g., an ANSI standard), there isn't
>much room for people to invent new features. An operating system has unlimited
>opportunity for people to implement their own favorite features.
Well, there's GNU emacs... Don't tell us people haven't got emotional
attachment to editors :)
Linus
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*** EOOH ***
From: laverman@cs.rug.nl (Bert Laverman)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 09:41:07 GMT
Organization: Dept. of Computing Science, Groningen University
Originator: laverman@rug16
Nntp-Posting-Host: rug16
Andy Tanenbaum writes:
> >Where is the sizeable group of people that want to evolve gcc in a way that
> >rms/FSF does not approve of?
> A compiler is not something people have much emotional attachment to. If
> the language to be compiled is a given (e.g., an ANSI standard), there isn't
> much room for people to invent new features. An operating system has unlimited
> opportunity for people to implement their own favorite features.
Try posting an announcement in one of the gnu groups about porting FSF software
to the Macintosh... ;-)
People will be emotional about anything they make, and more so if others try to
do unexpected things with it. Software is no exception.
If I remeber well, the only real attempt at global coordination of Minix projects
has been Glen Overby's Projects directory at plains. Problem is that usually
people don't want to announce all of their projects, because they are not sure
about whether or when they will finish it.
Fred was ready, and he told me he even set up big plans for only sending
out his stuff to people who could prove they owned an original. PH was sceptical
about his ability to check this, and their ability to check Fred. They were even
less enthausiastic about his using the name "Minix" in the name of the final
product. sigh.
I've seen some of his code. Too bad he only works on PCs. Some of the ideas
and comments floating around in the course of the current discussion were
fixed by Fred; centralized system call server, dynamically added servers
who can then serve new system calls. He ran TCP/IP as an added server.
Sure, Fred has an unusual personality, and sometimes an attitude that
smells of simply liking to run into a brick wall (not literally, please),
but he is one hell of a programmer, and when he was still unemployed he
had just the dynamism needed to get a large Minix rework done. I'ld
allmost feel sorry for the fact that he has a job now. ;-)
Perhaps we can use all this shouting and selfreflecting caused by the
Linux wars to some good end. Glen Overby had the right idea in setting up
a central site for collecting project info and ideas. What actually is
needed is someone to volunteer maintaining such a database. Just saying
"dump it here" will only transform anarchy to organized anarchy.
Also portability of patches is currently far from ideal. As the recent
sighup/init/getty activity shows, we have several packages, some of
which are PC only, while others are ST only, and again others have simply
never been tested on a wider range of machines.
We have for the FS:
- symbolic links, multi-threading
For mm:
- ??
kernel:
- virtual consoles (standard on ST, addon on PC), sighup,
the kub scheduler
tools:
- new init, boot packages, shoelace
lib:
- ??
commands:
- zillions of programs
I would like to suggest to those that built a patch set, to try and
collect as much as possible info on portability, interference with other
major patch sets, reliance on other major patch sets, and include this
info with their patch sets. It would greatly help if an enthausiastic
ST owner, having found a nice feature for his system, would not be
(unpleasantly) surprised by the fact that the patch is only for PCs.
Or vice versa of course.
Greetings, Bert
---
#include <std/disclaimer>
Bert Laverman, Dept. of Computing Science, Groningen University
Friendly mail to: laverman@cs.rug.nl The rest to: /dev/null
--
#include <std/disclaimer>
Bert Laverman, Dept. of Computing Science, Groningen University
Friendly mail to: laverman@cs.rug.nl The rest to: /dev/null
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From: kentd@FtCollins.NCR.com (Kent Dalton)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 5 Feb 92 09:23:56 GMT
Organization: NCR Microelectronics, Ft. Collins, CO
In-reply-to: ast@cs.vu.nl's message of 3 Feb 92 22:46:40 GMT
>>>>> On 3 Feb 92 22:46:40 GMT, ast@cs.vu.nl (Andrew "Dice" Tanenbaum) said:
Andy> As an aside, for those folks who don't read news headers, Linus is
Andy> in Finland and I am in The Netherlands. Are we reaching a
Andy> situation where another critical industry, free software, that had
Andy> been totally dominated by the U.S. is being taken over by the
Andy> foreign competition?
I prefer to think of it as indicative of the fact that the U.S. is still
the pioneer when it comes to new ideas and technologies. The rest of
the world just follows along, trying to refine and capitalize upon our
new developments. :^)
Andy> Will we soon see President Bush coming to Europe with Richard
Andy> Stallman and Rick Rashid in tow, demanding that Europe import more
Andy> American free software?
Be glad software isn't as important as oil. ;^)
--
/**************************************************************************/
/* Kent Dalton * EMail: Kent.Dalton@FtCollinsCO.NCR.COM */
/* NCR Microelectronics * CIS: 72320,3306 */
/* 2001 Danfield Ct. MS470A * */
/* Fort Collins, Colorado 80525 * (303) 223-5100 X-319 */
/**************************************************************************/
I've got an IDEA!! Why don't I STARE at you so HARD,
you forget your SOCIAL SECURITY NUMBER!!
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From: nao@sala.sony.co.jp (HAMADA Naoki)
Newsgroups: comp.os.minix
Subject: Re: Unhappy campers
Date: 6 Feb 92 12:08:51 GMT
Reply-To: nao@sala.sony.co.jp
Organization: Science Art Laboratory, Tokyo, Japan.
In-Reply-To: ast@cs.vu.nl's message of 3 Feb 92 22:46:40 GMT
Nntp-Posting-Host: skyline
Greetings!
In article <12667@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
(most stuffs omitted)
> If you don't have that journal, you can FTP the paper from
> ftp.cs.vu.nl (192.31.231.42) in directory amoeba/papers as comp_sys.tex.Z
> (compressed TeX source) or comp_sys.ps.Z (compressed PostScript).
I am so much interested in this paper, but I cannot get it. The ftp
server of ftp.cs.vu.nl rejects my connection because the IP address of
machines in my site (and most sites in Japan), from machines outside
of Japan, cannot be resolved by ptr. Is there anyone who has fetched
it and placed it in annonymous ftp? Archie servers seem to have no
idea.
Thanks in advance.
-HAMADA Naoki
Naoki is my first name.
nao@sala.sony.co.jp
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From: awoodhull@hamp.hampshire.edu
Newsgroups: comp.os.minix
Subject: Minix for 8088? Yes!
Date: 4 Feb 92 15:10:46 GMT
Organization: Hampshire College
Subject: Minix for 8088? Yes!
Some of the correspondence about Minix vs. Linux has argued that the
8088 compatibility of Minix is no longer important, because 80386
machines are not that much more expensive now.
That may be true when you talk about new machines, but students are
also in the market for used machines. I got a system quite competent to
run Minix, a PC clone with two 360K floppy drives, for $75 recently at
a yard sale. You aren't going to find second hand '386s for a while
yet.
Like ast I am also a professor. I expect to be teaching an OS course
using Minix in Nicaragua next year. There, as in many other places
outside the over-developed world, availability of entry-level or used
computer equipment for student use is the best that most students can
hope for. For the purpose for which it was created, continued
compatibility of Minix with low-end hardware is definitely worth
maintaining, and I hope ast will not change his target.
Linux also sounds like a nice experiment, for a different purpose. I
may decide to play with it, too, after I get Minix working on my new
'486. I don't think I will use Linux in my teaching, however.
Albert S. Woodhull
School of Natural Science, Hampshire College, Amherst, MA 01002
awoodhull@hamp.hampshire.edu, woodhull@dawn.hampshire.edu
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From: dmiller@acg.uucp (David Miller)
Newsgroups: comp.os.minix
Subject: Linux is Obsolete and follow up postings
Date: 3 Feb 92 01:03:46 GMT
Distribution: all
Organization: AppliedComputerGroup
As an observer interested in operating system design, I couldn't resist this
thread. Please realize that I am not really experienced with minux
or linux: I have been into unix for many years. First, a few observations:
Minix was written to be an educational tool for ASTs' classes, not a commercial
operating system. It was never a design parameter to have it run freely
available source code for unix systems. I think it was also a statement of
how operating systems should be designed, with a micro kernel and seperate
processes covering as much of the required functionality as possible.
Linux was written mostly as a learning exercise on Linus part - how to
program the 386 family. Designing the ultimate operating system was not
an objective. Providing a usable, free platform that would run all sorts
of widely available free software was a consideration, and one that appears
to have been well met.
Criticism from anyone that either of these systems isn't what *they* would
like it to be is misplaced. After all, anybody that has a computer that will
run either system is free to do what Linus and Andrew did: write your own!
I, for one, applaud Linus for his considerable effort in developing Linux
and his decision to make it free to everybody. I applaud AST for his
effort to make minix affordable - I have real trouble relating to complaints
that minix isn't free. If you can afford the time to explore minix, and a
basic computer system, $150 is not much more - and you do get a book to go
with it.
Next, a few questions for the professor:
Is minix supposed to be a "real operating system" or an educational tool ?
As an educational tool it is an excellent work. As a real operating system
it presents some terribly rough edges (why no malloc() ?, just for starters)
My feeling from reading The Book and listening to postings here is that you
wanted a tool to teach your classes, and a lot of others wanted to play with
an affordable operating system. These others have been trying to bolt on
enough features to make it a "real operating system", with less than
outstanding success.
Why split fundemental os functions, such as memory management, into user
processes? As all good *nix gurus know, the means to success is to
divide and conquer, with the goal being to *simplify* the problem into
managable, well defined components. If splitting basic parts of the
operating system into user space processes complicates the function by
introducing additional mechanisms (message passing, complicated signals),
have we met the objective of simplifying the design and implementation?
I agree that *nix has suffered a bad case of feature-itis - especially
sysVr4. Perhaps the features that people want for either functionality
or compatibility could be offered by run-time loadable modules/libraries
that offer these features. The micro-kernel would still be a base-level
resource manager that also routes function requests to the appropriate
module/library. The modules could be threads or user processes. (I think
- os hackers please correct me :-) )
Just my $.04 worth - please feel free to post or email responses.
I have no formal progressive training in computer science, so I am really
asking these questions in ignorance. I suspect a lot of others on the
net have similar questions in their own minds, but I've been wrong before.
--
-- David
David Miller Phone: (207) 873-3317
Applied Computer Group Fax: (207) 872-5018
5 Kimball Street UUCP: uunet!acg!dmiller
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From: rdc30@nmrdc1.nmrdc.nnmc.navy.mil (LCDR Michael E. Dobson)
Newsgroups: comp.os.minix
Subject: Re: Fred returning from the dead <was Unhappy campers>
Date: 6 Feb 92 13:18:22 GMT
Organization: Naval Medical Research & Development Command
In article <1992Feb4.172131.18145@philce.ce.philips.nl> meulenbr@ce.philips.nl (Frans Meulenbroeks) writes:
>
>ast@cs.vu.nl (Andy Tanenbaum) writes:
>
>>Suppose Fred van Kempen returns from the dead and wants to take over, creating
>
>Just a remark for the readers. As far as I know Fred is not physically dead.
>If english is not your native language (just like mine) you might
>conclude otherwise from ast's words. Fred is only electronically dead.
>
He's not electronicly dead any longer either. I and several others
involved with MUGNET have received electronic communications from him, that
is unless our hosts are haunted by Fred's electronic spirit.
--
Mike Dobson, Sys Admin for | Internet: rdc30@nmrdc1.nmrdc.nnmc.navy.mil
nmrdc1.nmrdc.nnmc.navy.mil | UUCP: ...uunet!mimsy!nmrdc1!rdc30
AT&T 3B2/600G Sys V R 3.2.2 | BITNET: dobson@usuhsb or nrd0mxd@vmnmdsc
WIN/TCP for 3B2 | MCI-Mail: 377-2719 or 0003772719@mcimail.com
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From: michael@gandalf.informatik.rwth-aachen.de (Michael Haardt)
Newsgroups: comp.os.minix
Subject: 1.6.17 summary and why I think AST is right.
Date: 6 Feb 92 20:07:25 GMT
Reply-To: u31b3hs@messua.informatik.rwth-aachen.de (Michael Haardt)
Organization: Gandalf - a 386-20 machine
Nntp-Posting-Host: kaa
I will first give a summary of what you can expect from MINIX in *near*
future, and then explain why I think AST is right.
Some time ago, I asked for details about the next MINIX release (1.6.17).
I got some response, but only from people running 1.6.16. The following
informations are not official and may be wrong, but they are all I know
at the moment. Correct me if something is wrong:
- The 1.6.17 patches will be relative to 1.5 as shipped by PH.
- The header files are clean.
- The two types of filesystems can be used together.
- The signal handling is rewritten for POSIX. The old bug is removed.
- The ANSI compiler (available from Transmediar, I guess) comes with
compiler binaries and new libraries.
- There don't seem to be support for the Amoeba network protocol.
- times(2) returns a correct value. termios(2) is implemented, but it's
more a hack. I don't know if "implemented" means in the kernel, or the
current emulation.
- There is no documentation about the new filesystem. There is a new fsck
and a new mkfs, don't know about de.
- With the ANSI compiler, there is better floating point support.
- The scheduler is improved, but not as good as written by Kai-Uwe Bloem.
I asked these things to get facts for the decision if I should upgrade to
MINIX 1.6.17 or to Linux after the examens are over. Well, the decision
is made: I will upgrade to Linux at the end of the month and remove MINIX
from my winchester, when Linux runs all the software I need and which currently
runs under MINIX 1.5 with heavy patches. I guess this may take up to two
months. These are the main reasons for my decision:
- There is no "current" MINIX release, which can be used as basis for
patches and nobody knows, when 1.6.17 will appear.
- The library contains several bugs and from what I have heard, there is
no work done at them. There will not be a new compiler, and the 16 bit
users still have to use buggy ACK.
- 1.6.17 should offer more POSIX, but a complete termios is still missing.
- I doubt that there is still much development for 16 bit users.
I think I will stop maintaining the MINIX software list in a few months.
Anyone out there, who would like to continue it? Until Linux runs
*perfect* on my machine, each update of Origami will still run on 16-bit
MINIX. I will announce when the last of these versions appears.
In my opinion, AST is right in his decision about MINIX. I read the flame
war and can't resist to say that I like MINIX the way it is, now where
there is Linux. MINIX has some advantages:
- You can start playing with it without a winchester, you can even
compile programs. I did this a few years ago.
- It is so small, you don't need to know much to get a small system which
runs ok.
- There is the book. Ok, only for version 1.3, but most of it is still
valid.
- MINIX is an example of a non-monolithic kernel. Call it a microkernel
or a hack to overcome braindamaged hardware: It demonstrates a concept,
with its pros and cons -- a documented concept.
In my eyes, it is a nice system for first steps in UNIX and systems
programming. I learned most of what I know about UNIX with MINIX, in
all areas, from programming in C under UNIX to system administration
(and security holes:) MINIX grew with me: 1.5.xx upgrades, virtual
consoles, mail & news, text processing, crosscompiling etc. Now it is
too small for me. I don't need a teaching system anymore, I would like
to get a more complicated and featureful UNIX, and there is one: Linux.
Back in the old days, v7 was state of the art. There was MINIX which
offered most of it. In one or two years, POSIX is what you are used to
see. Hopefully, there will be MINIX, offering most of it, with a new
book, for people who want to run a small system to play and experiment
with.
Stop flaming, MINIX and Linux are two different systems with different
purposes. One is a teaching tool (and a good one I think), the other is
real UNIX for real hackers.
Michael
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From: dingbat@diku.dk (Niels Skov Olsen)
Newsgroups: comp.os.minix
Subject: Re: 1.6.17 summary and why I think AST is right.
Date: 10 Feb 92 17:33:39 GMT
Organization: Department of Computer Science, U of Copenhagen
michael@gandalf.informatik.rwth-aachen.de (Michael Haardt) writes:
>Stop flaming, MINIX and Linux are two different systems with different
>purposes. One is a teaching tool (and a good one I think), the other is
>real UNIX for real hackers.
Hear, hear! And now Linux articles in alt.os.linux (or comp.os.misc
if your site don't receive alt.*) and Minix articles here.
eoff (end of flame fest :-)
Niels
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