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Andrew Morton on Kernel Hacking 46

Posted by Hemos from the smart-people-often-say-smart-things dept.
Susie Denmark writes "Linux Format has a brief interview with Andrew Morton, the maintainer of the Linux kernel 2.6 tree. Andrew discusses the debates behind revision control systems (the BitKeeper and CVS), new kernel features and his own -mm tree. Will the issue of using RCSes in the kernel tree ever die down? Does it really matter?"
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Andrew Morton on Kernel Hacking More

Andrew Morton on Kernel Hacking

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  • He may be maintaining the 2.6 tree... (Score:5, Funny)

    by brilinux ( 255400 ) on Monday November 21, 2005 @09:36AM (#14081062) Journal
    But what does he know about 2.7!!??

  • Gittish (Score:5, Informative)

    by minginqunt ( 225413 ) on Monday November 21, 2005 @09:42AM (#14081090) Homepage Journal
    > Will the issue of using RCSes in the kernel tree ever die down?

    Um, yes. It did so three months ago. It's called git [git.or.cz].

  • Wow (Score:5, Funny)

    by gowen ( 141411 ) <gwowen@gmail.com> on Monday November 21, 2005 @09:57AM (#14081165) Homepage Journal
    I'm suprised he finds the time, given the heavy load of muck raking biographies [amazon.com] that he manages to write.

  • rcs. (Score:5, Informative)

    by s4m7 ( 519684 ) on Monday November 21, 2005 @09:57AM (#14081167) Homepage

    Will the issue of using RCSes in the kernel tree ever die down?

    It more or less has since they've replaced bitkeeper with git [git.or.cz].

    Does it really matter?

    Well, it probably doesn't matter to you if you arent part of the tree-maintenance heirarchy, since individual developers don't need to use git directly to submit their patches, but the maintainers use them to keep track of who submitted what patches when, when they were merged, if they were tweaked etc. Many maintainers were uncomfortable with BitKeeper because it was a proprietary platform meaning that they could go out of buiness, revoke linus's liscence, or any number of other things could go wrong. That's exactly what happened and so git was created to replace it.

    using some kind of RCS/SCM solution is absolutely critical in a project as large as the linux kernel, if for no reason other than to have a history of where stuff came from. If they'd been using something from the get-go it would be a lot harder for SCO to make the claims that they have.

    • Interesting.. the issue with bitkeeper always seemed to me that it was really non-free software. I've taken a look at GIT's COPYING file, and it looks like this:

      --

      Note that the only valid version of the GPL as far as this project
      is concerned is _this_ particular version of the license (ie v2, not
      v2.2 or v3.x or whatever), unless explicitly otherwise stated.

      HOWEVER, in order to allow a migration to GPLv3 if that seems like
      a good idea, I also ask that people involved w

      • Perhaps I should have said non-free instead of proprietary, the specific implications of one vs. the other are fairly lost on me. Net result, BitKeeper posed some kind of problem IP-wise, and has been replaced.

        and yeah, people are worried about GPL3. Would you be eager to liscence your software under a license for which the specific language is not yet known?

    • Re:rcs. (Score:4, Informative)

      by iabervon ( 1971 ) on Monday November 21, 2005 @02:30PM (#14083486) Homepage Journal
      Actually, git has a number of nice features for individual developers and even testers. There's a great thing called "bisect" for finding what broke the system. You tell it "this version worked, and that version didn't." Then it checks out for you another version to try. You build it, test it, and tell it if it works. Then it checks out another one for you. After O(log(n)) steps, it tells you which patch broke things. It's actually faster than trying to figure out which patch it was by thinking about the problem.

      The reason this sort of thing is possible is that git is a free system, and people can write the tools they need to interact with it. It's true that most people didn't have to use BK, but git is useful in many more situations and there aren't the licensing reasons not to use it, so you're likely to see people tell you to use git just to move data around.

      For that matter, git has extensions to the patch format, so you need to use it if you want to make certain types of patches in ways that are easy to review (such as a patch that renames a file; standard diff requires the reviewer to figure out what is different between the lines removed from the old name and the lines added to the new one).
  • If you like Git but you want to use multiple platforms try Mercurial: http://www.selenic.com/mercurial/wiki/index.cgi [selenic.com] Performance is excellent, it is written in Python. So far version 0.7, but projects is very active.

    • Re:Multiplatform VCS (Score:3, Informative)

      by boa13 ( 548222 )
      I frequently look at both projects, and it seems to me that Git is more active and has a bigger base (users and developers). These past ten weeks or so, Mercurial seems to have slowed down, while Git has accelerated towards 1.0. Besides, Git performance has improved a lot in the past few months, and disk usage has gone way down, the comparisons you can find on the web are now meaningless and outdated. Also, Git has been ported to Cygwin, and works on most Unices.

      However, Mercurial offers a better user exper
      • Mercurial offers a better user experience, is easier to get into, is truly-cross-platform, and so might be a better choice for smaller projects.

        Why "smaller projects" in particular? It's designed to scale well with tree size, and people are using it on the Linux kernel source.

      • Re:Multiplatform VCS (Score:3, Informative)

        by MenTaLguY ( 5483 )
        Mercurial might be farther along if Larry McVoy hadn't (about ten weeks ago, curiously enough) gotten rid of one of their core developers by threatening their employer [lwn.net].

        BitKeeper is pure dag-nasty evil.

  • Andrew... :) (Score:2, Funny)

    by ovit ( 246181 )
    I actually had the pleasure of working at the same company as Andrew a few years back...

    We didn't directly work together (he was, obviousley doing kernel stuff, and I was doing UI back then), but I used to invent excuses to go talk to him, just to try to soak up some of that kernel hacking aura...

    Must have worked somewhat since now I'm doing driver development!

  • Great professionalism! (Score:4, Insightful)

    by joib ( 70841 ) on Monday November 21, 2005 @11:00AM (#14081544)
    So, uh, it seems that AM is a professional level headed guy. No surprises there really.

    But to my gripe: Starting the interview with "Do you think it was good to have had the time with BitKeeper in kernel development, or should they have stuck with CVS?". Gee, being so in tune with what's happening in kernel land just makes want to run to the nearest newsstand and get the latest "Linux Format": "The essential read for all Linux users".
    • Gee, being so in tune with what's happening in kernel land just makes want to run to the nearest newsstand and get the latest "Linux Format": "The essential read for all Linux users".

      You have a point, but don't be too hard on "Linux Format", it's a pretty decent magazine. I'm not a subscriber, but I look out for it in the newsagents and buy it quite often. They cover a lot of ground in an accessible way - great if you are not a Linux guru.

    • From TFA

      In issue 74 of Linux Format, on the shelves now, we have an interview with kernel 2.6 maintainer Andrew Morton. Here are a few of the questions we asked Andrew, along with his answers

      If you ran out and bought the magazine in question you would have the whole interview. The posted article is a taster. A teaser if you will. The actual interview is much broader, and the first question reprinted here is a follow on question to the whole bitkeeper/ cvs/ git topic.

  • No Beard? (Score:2, Funny)

    by Skiron ( 735617 )
    Is that his picture - or the reporters mug shot?

    If so, then my first question would be:

    "Well Andrew, why haven't you got a hackers unruly beard then? Are you really a hacker?".

  • You What!! (Score:5, Insightful)

    by ObsessiveMathsFreak ( 773371 ) <obsessivemathsfreak.eircom@net> on Monday November 21, 2005 @11:52AM (#14081927) Homepage Journal
    Oh. My. Gods. From TFA

    AM: Well, we never even used CVS. Before BitKeeper we basically weren't using anything - just a bunch of patches sitting on Linus' hard drive and it uploaded occasionally. We had no tracking of what had gone in the kernel at all.

    Someone, please tell me this is a dream. Wake me from this nightmare. Dear gods!! There was no version control on the Linux Kernel!? How? What? When? Where? Why? WTF!!?

    I am not rightly able to comprehend the kind of confusion of ideas that would provoke such a situation.

    • Re:You What!! (Score:3, Informative)

      by Carewolf ( 581105 )
      You have version control in the fact that versions are realeased every now and then, you can just diff them manually.

      The lack of version control tool, does not mean the lack of version control. It is just done manually. While slower manual control is infinitely more flexible than computer assisted version control, which was why Linus waited until he found a tool that didn't hinder him too much.

    • Re:You What!! (Score:2, Funny)

      by Cramer ( 69040 )
      Nope. That's no dream. For most of a decade, the entire thing was run from Linus' INBOX. Various other kernel developers used CVS (etc.), but Linus HATES CVS. (And I don't blame him one bit.)
      • Nope. That's no dream. For most of a decade, the entire thing was run from Linus' INBOX. Various other kernel developers used CVS (etc.), but Linus HATES CVS. (And I don't blame him one bit.)

        I'm not sure why this was flagged funny.

        It was literally Linus' INBOX that ran things. He had a whole series of scripts to apply patches from the INBOX, etc. And one of the first things he made sure Larry Mcvoy did when implementing bitkeeper was have commands to send/recieve patches in a similar email format so he co

    • Re:You What!! (Score:1, Funny)

      by Anonymous Coward
      Yes just say it Linux sucks, computers suck, da intraweb sucks....

      Time for an exokernel already! Linux is not as good as everyone thinks it is... but its sure better than anything else we have right now that is usable... and if you want my opinion GNU sucks. I really wished someone that could do things correctly like djb [cr.yp.to] would start their own OS.

      There are only a dozen people in this generation that can do things correctly in the computer world, and djb happens to be one of them.

  • Stinking font (Score:4, Funny)

    by po8 ( 187055 ) on Monday November 21, 2005 @01:16PM (#14082794)

    The Linux Format folks really need to change the default font for their webpages, which appears to be Tahoma. I just spent two minutes of my life trying to figure out what a "dustering filesystem" is. Found a Googlewhack, anyhow.

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