Slashdot Mirror
Andy Tanenbaum on 'Who Wrote Linux'
Andy Tanenbaum writes "Ken Brown has just released a book on open source code. In it, he claims (1) to have interviewed me, and (2) that Linus Torvalds didn't write Linux. I think Brown is batting .500, which is not bad for an amateur (for people other than Americans, Japanese, and Cubans, this is an obscure reference to baseball). Since I am one of the principals in this matter, I thought it might be useful for me to put my 2 eurocents' worth into the hopper. If you were weren't hacking much code in the 1980s, you might learn something." Tanenbaum's description of the interview process with Brown is classic. See also Slashdot's original story and Linus' reply.
Poor old Ken Brown must be wondering how wise it was to have made that particular trip now! :-)
Curious that someone would spend all that cash and yet have done so little research. Smells of hidden agendas, or no-so-hidden agendas perhaps?
The best part has to be: "But the code was his. The proof of this is that he messed the design up."
Andrew Tanenbaum discovers slashdot effect. Adti disputes it, citing that others discovered it first and that Tannenbaum just copied it.
Actually, since the interview is not reachable anymore, I assume it is right what you said. But Tannenbaum is right in his sense, a Makrokernel does not really make that much sense, it is easier to program because you simply have method calls instead of messages, but you run into driver compiles, crashes due to the strong binding etc... Mach at least in its early incarnations was not the best example of a Microkernel, neither is the vaporware hurd, which probably will be finished in about 100 years, but improved Mach kernels derived from newer incarnations already have shown how powerful and stable the concept can be, Two words:AIX and MacOSX both based on Mach kernels and both excellent and fast operating systems.
Some Notes on the "Who wrote Linux" Kerfuffle, Release 1.1
Background
The history of UNIX and its various children and grandchildren has been in the news recently as a result of a book from the Alexis de Tocqueville Institution. Since I was involved in part of this history, I feel I have an obligation to set the record straight and correct some extremely serious errors. But first some background information.
Ken Brown, President of the Alexis de Tocqueville Institution, contacted me in early March. He said he was writing a book on the history of UNIX and would like to interview me. Since I have written 15 books and have been involved in the history of UNIX in several ways, I said I was willing to help out. I have been interviewed by many people for many reasons over the years, and have been on Dutch and US TV and radio and in various newspapers and magazines, so I didn't think too much about it.
Brown flew over to Amsterdam to interview me on 23 March 2004. Apparently I was the only reason for his coming to Europe. The interview got off to a shaky start, roughly paraphrased as follows:
AST: "What's the Alexis de Tocqueville Institution?"
KB: We do public policy work
AST: A think tank, like the Rand Corporation?
KB: Sort of
AST: What does it do?
KB: Issue reports and books
AST: Who funds it?
KB: We have multiple funding sources
AST: Is SCO one of them? Is this about the SCO lawsuit?
KB: We have multiple funding sources
AST: Is Microsoft one of them?
KB: We have multiple funding sources
He was extremely evasive about why he was there and who was funding him. He just kept saying he was just writing a book about the history of UNIX. I asked him what he thought of Peter Salus' book, A Quarter Century of UNIX. He'd never heard of it! I mean, if you are writing a book on the history of UNIX and flying 3000 miles to interview some guy about the subject, wouldn't it make sense to at least go to amazon.com and type "history unix" in the search box, in which case Salus' book is the first hit? For $28 (and free shipping if you play your cards right) you could learn an awful lot about the material and not get any jet lag. As I sooned learned, Brown is not the sharpest knife in the drawer, but I was already suspicious. As a long-time author, I know it makes sense to at least be aware of what the competition is. He didn't bother.
UNIX and Me
I didn't think it odd that Brown would want to interview me about the history of UNIX. There are worse people to ask. In the late 1970s and early 1980s, I spent several summers in the UNIX group (Dept. 1127) at Bell Labs. I knew Ken Thompson, Dennis Ritchie, and the rest of the people involved in the development of UNIX. I have stayed at Rob Pike's house and Al Aho's house for extended periods of time. Dennis Ritchie, Steve Johnson, and Peter Weinberger, among others have stayed at my house in Amsterdam. Three of my Ph.D. students have worked in the UNIX group at Bell Labs and one of them is a permanent staff member now.
Oddly enough, when I was at Bell Labs, my interest was not operating systems, although I had written one and published a paper about it (see "Software - Practice & Experience," vol. 2, pp. 109-119, 1973). My interest then was compilers, since I was the chief designer of the the Amsterdam Compiler Kit (see Commun. of the ACM, vol. 26, pp. 654-660, Sept. 1983.). I spent some time there discussing compilers with Steve Johnson, networking with Greg Chesson, writing tools with Lorinda Cherry, and book authoring with Brian Kernighan, among many others. I also became friends with the other "foreigner," there, Bjarne Stroustrup, who would later go on to design and implement C++.
In short, although I had nothing to do with the development of the original UNIX, I knew all the people involved and much of the history quite well. Furthermore, my contact with the UNIX group at Bell Labs was not a secret; I even thanked them all for having me as a summer visitor in the preface to the first editio
Some Notes on the "Who wrote Linux" Kerfuffle, Release 1.1
Background
The history of UNIX and its various children and grandchildren has been in the news recently as a result of a book from the Alexis de Tocqueville Institution. Since I was involved in part of this history, I feel I have an obligation to set the record straight and correct some extremely serious errors. But first some background information.
Ken Brown, President of the Alexis de Tocqueville Institution, contacted me in early March. He said he was writing a book on the history of UNIX and would like to interview me. Since I have written 15 books and have been involved in the history of UNIX in several ways, I said I was willing to help out. I have been interviewed by many people for many reasons over the years, and have been on Dutch and US TV and radio and in various newspapers and magazines, so I didn't think too much about it.
Brown flew over to Amsterdam to interview me on 23 March 2004. Apparently I was the only reason for his coming to Europe. The interview got off to a shaky start, roughly paraphrased as follows:
AST: "What's the Alexis de Tocqueville Institution?"
KB: We do public policy work
AST: A think tank, like the Rand Corporation?
KB: Sort of
AST: What does it do?
KB: Issue reports and books
AST: Who funds it?
KB: We have multiple funding sources
AST: Is SCO one of them? Is this about the SCO lawsuit?
KB: We have multiple funding sources
AST: Is Microsoft one of them?
KB: We have multiple funding sources
He was extremely evasive about why he was there and who was funding him. He just kept saying he was just writing a book about the history of UNIX. I asked him what he thought of Peter Salus' book, A Quarter Century of UNIX. He'd never heard of it! I mean, if you are writing a book on the history of UNIX and flying 3000 miles to interview some guy about the subject, wouldn't it make sense to at least go to amazon.com and type "history unix" in the search box, in which case Salus' book is the first hit? For $28 (and free shipping if you play your cards right) you could learn an awful lot about the material and not get any jet lag. As I sooned learned, Brown is not the sharpest knife in the drawer, but I was already suspicious. As a long-time author, I know it makes sense to at least be aware of what the competition is. He didn't bother.
UNIX and Me
I didn't think it odd that Brown would want to interview me about the history of UNIX. There are worse people to ask. In the late 1970s and early 1980s, I spent several summers in the UNIX group (Dept. 1127) at Bell Labs. I knew Ken Thompson, Dennis Ritchie, and the rest of the people involved in the development of UNIX. I have stayed at Rob Pike's house and Al Aho's house for extended periods of time. Dennis Ritchie, Steve Johnson, and Peter Weinberger, among others have stayed at my house in Amsterdam. Three of my Ph.D. students have worked in the UNIX group at Bell Labs and one of them is a permanent staff member now.
Oddly enough, when I was at Bell Labs, my interest was not operating systems, although I had written one and published a paper about it (see "Software - Practice & Experience," vol. 2, pp. 109-119, 1973). My interest then was compilers, since I was the chief designer of the the Amsterdam Compiler Kit (see Commun. of the ACM, vol. 26, pp. 654-660, Sept. 1983.). I spent some time there disc
Start with a premise, do little or no research, and declare conclusions. When the truth is pointed out, get indignant.
Granted, I haven't read the book in question, but this was a very enlightening article. I especially loved the comment that insinuates that Linus could have done a better job if he HAD stolen the code, than he did.
Visit Lockjaw's Lair. He won't bite.
...and to make them perform reasonably well, both of these have hacks (server collocation, etc.) that remove the whole reason for microkernels in the first place.
Don't fall for the hype.
On the other hand, QNX is actually pretty true to the concept.
In a kernel there is a lot of interaction between the various parts. In a monolithic kernel these interactions are performed by simple subroutine calls and manipulation of shared data. In a microkernel these interactions require a more complex switch between tasks, and message passing. In exchange, you get better protection of one part from the others, which makes tracking down bugs quicker.
John Sauter (J_Sauter@Empire.Net)
"It was the dawn of the third age of mankind. Ten years after the Earth-Minbari war,
"the Babylon project was a dream given form
"Its goal: to prevent another war by creating a place where humans and aliens could work out their differences peacefully.
"It's a port-of-call, home away from home for diplomats, hustlers, entrepreneurs, and wanderers.
"Humans and aliens wrapped in two million five hundred thousand tons of spinning metal, all alone in the night.
"It can be a dangerous place, but it's our last, best hope for peace.
"This is the story of the last of the Babylon stations. The year is 2258.
"The name of the place is Babylon5."
"Oh, and GNU Hurd was just released."
Javascript + Nintendo DSi = DSiCade
Well, there are certainly benefits to a modular micro-kernel design. I wouldn't deny it (and haven't). But there are also drawbacks (message passing is terribly hard to make secure in a multi-tasking context, and is frequently slower than dirt. Add to that some of the braindead design decisions of the x386 w.r.t. privileged processes...) Yuck.
Treating the micro v. monolithic debate as a solved problem ("microkernels win!") is as idiotic as suggesting that object orientation is the ideal solution to all programming problems.
Athletic Scholarships to universities make as much sense as academic scholarships to sports teams.
SCO wrote it. From scratch. Now cough up that $699!
Sigs for Nerds. Sigs that Matter.
Athletic Scholarships to universities make as much sense as academic scholarships to sports teams.
What more needs to be said !
Add QNX to that. It doesn't get much more microkernel than that, and I think noone would argue that QNX is slow.
As for Darwin; it was certainly slow on my x86 laptop, but it's not lacking any speed on my iBook. I guess that says something about the quality of the x86 port (hint: there is no such thing).
Poor Andy seems a bit too stuck in his I am right and everyone who disagrees is wrong. I have a book here (Distributed Systems: Principles and Paradigms) in which he claims that a 20% performance loss is not so bad, in exchange for all the benefits a microkernel brings. I most sincerely think that is a ridiculous statement, but fortunately, it doesn't have to be that way. I believe microkernels need not incurr any significant performance penalty at all.
Please correct me if I got my facts wrong.
AST lists several independently developed systems of equivalent complexity to Mixix 1.0 / System 7. Here are a couple more I found:
OMU (6809 processor, ported to 68000) roughly system 7 but only single user, integrated shell.
http://tallyho.bc.nu/~steve/omu.html
UZI (Z80 processor, ported to 180, 280) roughly system 7: multitasking
http://www.dougbraun.com/uzi.html
To call OS X a Mach system is a bit disengenious. All I/O operations are handled by the "BSD Subsystem" for performance reasons. This means that all file and network I/O (along with the file security descriptions) are in a "monolithic subsystem" of the uK. Needles to say, this is the most performance-intense section of a UNIX (any?) system. A lot of the message-passing is therefore avoided; and the performance costs that those message passes would incur. Take a look at this url: OS X System Overview See that dotted-line that stretches from the kernel to userland? Tannenbaum would not approve.
The wheel is turning, but the hamster is dead.
I don't think Tanenbaum is bitter. He just wants to point this out.
Since I don't think anyone here has RTFA'd (/. effect and all) it's not worth judging right now. I think it's pretty classy of Tanenbaum to step up and offer some perspective on the AdTI FUD. If he does that as someone who still doesn't buy into Linux, that makes it all the more credible. Do we really want every response to this to be written by a Linux fanboy?
Google confirms: Ruby is the world's most beloved programm
my first reaction to this attack was, 'who the f### is Ken Brown? as they taught me back in school, 'always consider the source' --if this guy's attacking Linux, he'd better have some solid credentials in the computer industry, right? well, all it took was a Google search, and the first link I hit told me all i need to know: Anti-Open Source lobbyists need love, too Friday October 25, 2002 - [ 03:00 PM GMT ] Topics: Migration - By Robin "Roblimo" Miller - I felt bad for Ken Brown of the Alexis De Toqueville Institution (AdTI) last week... http://www.newsforge.com/business/02/10/25/056218. shtml?tid=19
thanks to Roblimo, we have a first-hand account of Ken Brown's shameless FUD-ing, back in 2002--read this link for a cuttingly funny look at Mr. Browns earlier efforts;>
you gotta love the 'thousands of eyeballs' that are working on our side--it more than offsets what M$ gets from spreading it's dirty money around...
-DWitt
ps. methinks Brown's IP has just gone down the tubes--thank you very much Andy Tanenbaum!
Whatever anyone does - do not read Brown's book when it comes out.
Thanks to Mr. Tanenbaum, we have the proof here:
People can create operating systems on their own. Even UNIX-like operating systems. Linus learned from Mr. Tanenbaum. Linus wrote the first kernel, published it and asked for input, which the rest of the world provided.
Linus then acted as a proper project manager, and the rest is history.
So again, whatever people do - do not buy the book.
Now, here's the problem: if we talk about this upcoming book, people will want to buy it. It's the Gibson Effect - the more its denounced, the more people will want to read it, and next thing you know there will be lines of people at the bookstores claiming they can see Jesus's face on this book.
So instead, I recommend to all intelligent folks in the programming community: ignore it. From here on out, don't even refer to the book by name, or its foundation, or the author. The more we pretend it doesn't exist and it's not important, the less interest people will have in it. If someone asks (such as a Pointy Haired Boss guy), shrug and lie as you say "No idea. I heard it was some book, but that it wasn't that good." And then shut up and leave it at that.
Don't give these guys free advertising. Don't even give them an ounce of respect, they don't deserve it.
52 Weeks, 52 Religions with John Hummel
I read the article from the Groklaw link before it showed up on /. Tanenbaum says that at least five different people single handedly wrote a UNIX-like kernel and that Linus clearly wrote Linux. He also says that Brown, the person who interviewed him, was completely clueless and obviously pushing an agenda.
The bitter part comes in the last couple of paragraphs, where he takes the opportunity to say that Linus was a misguided kid who should have paid more attention in class such that he would have seen the obvious superiority of a microkernel over a macrokernel. But he's quick to point out that he and Linus are not enemies.
"The legitimate powers of government extend only to such acts as are injurious to others." Thomas Jefferson.
In one of the "Revolution OS" interviews, he states he's merely the engineer, and RMS is more like the philosopher. I think he wants to remove himself from the political aspect and just enjoy the work. Think Einstein and the atomic bomb.
FLR
Windoz had a microkernel in the NT 3.51 days. It is way far from a microkernel today. There are some info about this on the NT 4 resource kit documentation.
cheers.
``If a program can't rewrite its own code, what good is it?'' - Mel
To summarize, let me call the part that securely multiplexes hardware the "kernel".
- Monolithic makes drivers share address space with the "kernel".
- With Microkernel, "kernel", drivers, filesystems, applications, etc each get their own address spaces.
- Exokernel makes drivers share address space with applications. (Hopefully, filesystems get their own process and address space.)
As you can see, as soon as you start partitioning applications into separate processes for security and robustness, the distinction between Exokernel and Microkernel becomes rather vague. The advantage of the Exokernel or VM approach is that you get the flexibility of keeping things like filesystems in a separate process for security and robustness, and things like video drivers in the same address space for performance. You might even have an X server as a separate process, but still allow full screen mode games that directly call the driver libraries for performance.IBM's VM was never that popular in its raw "Exokernel" mode with drivers in application space. However, it is still hugely popular as a way to run multiple Operating Systems as the "applications". Your mainframe can securely run multiple instances of S/390 Linux and traditional mainframe systems together.
Matt Loney of ZDNet UK is covering the story, including Andy Tanenbaum's two Euro-cents here. I don't think anyone at AdTI, least of all Ken Brown, is going to be living off royalties any time soon - "falls at the starting gate" indeed. ZD even mention AdTI's ties to Microsoft least there be any doubt, which is nice of them. :)
UNIX? They're not even circumcised! Savages!
12 years ago, who would have imagined that it is normal and in fact essential for a desktop OS to be able to smoothly handle many IO intensive processes at the same time?
I know many in the Linux community like to paint Mr. Tanenbaum as a bitter lunatic, but this is a great article, one that every Linux user/zealot should read.
First, he goes into the history of why people were souring on UNIX and the various independently-written UNIXalikes. These were mostly individual projects, which really sets the record straight for the people who seem to think that Linus was the first person to do this, and that Linus was somehow the only person intelligent and manly enough to write his own kernel.
At the same time, he lays out the history of UNIX clones, of which Linux was definitely one. It's surprising to me how many people seem to think of Linux as a great, independent OS, and fight so hard to deny that it has roots in UNIX. Of course these people are mostly young and don't know much about computer history. In that respect, this is an educational article.
And, yes, he does talk about the micro vs. monolithic kernel issue, but he does so without fanaticism, and, you know, what he says is generally correct. He's all for small and reliable software, which is something that UNIX was originally but rapidly became the antithesis of. Performance issues, back when people were using 4.77 and 8 MHz desktop processors, well, let's just say that things were different then. Now you have people writing big applications in Python. The real reason Linux ended up with a monolithic kernel is because that's what Linus understood and it was easier for him to write that way.
Writing a simple OS kernel is easy. I wrote one, and believe me, it wasn't that hard. At the university where I am a grad student, we require the undergrads to write most of an OS kernel (including virtual memory and a filesystem) in a one-semester course. I read alt.os.development regularly, and there are high school students who are writing OS kernels. (I'm often depressed by the fact that they are much better programmers than I am :-)
Writing a scalable, production-quality OS kernel is another matter entirely. That takes hundreds or thousands of person-years by talented programmers.
Ken Brown is obviously a complete shithead if he doesn't understand this distinction. AST's rebuttal made the facts of the matter abundantly clear, and I'm sure any competent OS developer he asked would have told him the same thing.
Thirteen years ago, I didn't give a flying FUCK about how outdatated Linus' monolithic kernel was. Remember, we were all running DOS, and desperate to break out of real mode hell.
Arguing about monolithic versus microkernel was like arguing about whether a starving man's meal should be vegetarian or not.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
Further you are comparing apples with oranges comparing a Mac to a PC
I object to your comparison between apples and oranges and Macs and PCs. Equating apples compared to oranges with Macs compared to PCs is like comparing comparisons between euphemisms with comparisons between idioms.
I really have to figure out how to do this scam. Get money from big corporations
They started off taking money from the Swiss. The process seems to go something like this:
1. Get some hack-journalist experience (overfunded and obscure policy journals publish damn near anything; ditto for the Washington Times, as long as it purports to be conservative).
2. Get to know rich people
--a. get cushy internships in college
--b. marry a lawyer at a Big Firm
3. Convince the rich people you know to pay you for hack journalism.
4. Use hack journalism to push dubious foreign-investment schemes
5. PROFIT!!!
The key is that business, academia, law, journalism and government don't really know how to function with one another. They want to, for both good and bad reasons, so a lot of the time they're willing to throw big money conferences, fellowships, publications and "research institutions" that are supposed to grease the wheels.
Added to this, washed-up bigwigs usually want some place to go, and their former friends often set up make-work jobs for them. Lose an election? Why don't you give a lecture once a month at my public policy school. Get shitcanned from your CEO job? Why don't you sit on my government advisory committee. Newspaper column dried up? How bout you be a fellow at my think-tank. And of course, all of these people need gophers, personal assistants, research aides, etc. - a whole industry of suckups scurrying around washups.
The pay is peanuts for the honorees, sometimes even nonexistent. But they like the honorary titles. In exchange, the institution that hands out the titles gets more prestige from having Big Names attached to it. Look at the name-dropping on AdTI website: Jack Kemp, Newt Gingrich (Republicans), John Norquist (Democrat). In turn, the aura of Big Names clustered around an institution makes it easier to sucker donors.
That's basically the scam: laundering prestige for money. All you have to do is Know People(tm).
Google confirms: Ruby is the world's most beloved programm
Treating the micro v. monolithic debate as a solved problem ("microkernels win!") is as idiotic as suggesting that object orientation is the ideal solution to all programming problems.
I'll agree with that. However, I can say that for the stuff I do, microkernels win. I've written a microkernel RTOS for an embedded system, and it had the following advantages for me:
1) It was easy to write. (Very modular)
2) It is easy to maintain. (Very modular, and because all interaction is done with messaging, you dont worry about the code you are doing now interacting in some unknown way with something else. ie. You can ignore the rest of the system except for the messages you send to it)
3) It is easy to give it strong deterministic real-time response. This is a big thing for me in the applications I use it for. Data ends up flowing from one task to another, and I just have to make sure my scheduler doesn't mess that up.
4) The overhead introduced by message passing was negligible (The RTOS was implemented to replace an existing system, and did so comfortably)
5) Its really easy to make stable and reliable systems, because everything is chopped up into small well understood sections with well defined interaction between sections.
Microkernels might have slightly lower throughput than monolithic macrokernels, but I am not running a batch transaction processor.
For desktop use, I want controlled latency and reliability. I don't feel that Linux gives me all that it should in those departments, though I use it because it is better than most (with some patching). Kernel modules feel like the worst of both worlds to me.
So, given the priorities I stated above, I think I would prefer a microkernel OS, all other things being equal. I'd jump ship from Linux to one, if most other things are equal.
Other people will have other priorities and I encourage them to use whatever works for them.
---
After seeing all the responses yesterday, I think I have a better idea of Ken Brown's motivation in coming to see me and also his motivation in writing the book. If you are curious, take a look at
www.cs.vu.nl/~ast/brown/followup
Andy Tanenbaum