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    SubjectRe: Availability of kdb


    On Wed, 6 Sep 2000, Tigran Aivazian wrote:
    >
    > very nice monologue, thanks. It would be great to know Linus' opinion. I
    > mean, I knew Linus' opinion of some years' ago but perhaps it changed? He
    > is a living being and not some set of rules written in stone so perhaps
    > current stability/highquality of kdb suggests to Linus that it may be
    > (just maybe) acceptable into official tree?

    I don't like debuggers. Never have, probably never will. I use gdb all the
    time, but I tend to use it not as a debugger, but as a disassembler on
    steroids that you can program.

    None of the arguments for a kernel debugger has touched me in the least.
    And trust me, over the years I've heard quite a lot of them. In the end,
    they tend to boil down to basically:

    - it would be so much easier to do development, and we'd be able to add
    new things faster.

    And quite frankly, I don't care. I don't think kernel development should
    be "easy". I do not condone single-stepping through code to find the bug.
    I do not think that extra visibility into the system is necessarily a good
    thing.

    Apparently, if you follow the arguments, not having a kernel debugger
    leads to various maladies:
    - you crash when something goes wrong, and you fsck and it takes forever
    and you get frustrated.
    - people have given up on Linux kernel programming because it's too hard
    and too time-consuming
    - it takes longer to create new features.

    And nobody has explained to me why these are _bad_ things.

    To me, it's not a bug, it's a feature. Not only is it documented, but it's
    _good_, so it obviously cannot be a bug.

    "Takes longer to create new features" - this one in particular is not a
    very strong argument for having a debugger. It's not as if lack of
    features or new code would be a problem for Linux, or, in fact, for the
    software industry as a whole. Quite the reverse. My biggest job is to say
    "no" to new features, not trying to find them.

    Oh. And sure, when things crash and you fsck and you didn't even get a
    clue about what went wrong, you get frustrated. Tough. There are two kinds
    of reactions to that: you start being careful, or you start whining about
    a kernel debugger.

    Quite frankly, I'd rather weed out the people who don't start being
    careful early rather than late. That sounds callous, and by God, it _is_
    callous. But it's not the kind of "if you can't stand the heat, get out
    the the kitchen" kind of remark that some people take it for. No, it's
    something much more deeper: I'd rather not work with people who aren't
    careful. It's darwinism in software development.

    It's a cold, callous argument that says that there are two kinds of
    people, and I'd rather not work with the second kind. Live with it.

    I'm a bastard. I have absolutely no clue why people can ever think
    otherwise. Yet they do. People think I'm a nice guy, and the fact is that
    I'm a scheming, conniving bastard who doesn't care for any hurt feelings
    or lost hours of work if it just results in what I consider to be a better
    system.

    And I'm not just saying that. I'm really not a very nice person. I can say
    "I don't care" with a straight face, and really mean it.

    I happen to believe that not having a kernel debugger forces people to
    think about their problem on a different level than with a debugger. I
    think that without a debugger, you don't get into that mindset where you
    know how it behaves, and then you fix it from there. Without a debugger,
    you tend to think about problems another way. You want to understand
    things on a different _level_.

    It's partly "source vs binary", but it's more than that. It's not that you
    have to look at the sources (of course you have to - and any good debugger
    will make that _easy_). It's that you have to look at the level _above_
    sources. At the meaning of things. Without a debugger, you basically have
    to go the next step: understand what the program does. Not just that
    particular line.

    And quite frankly, for most of the real problems (as opposed to the stupid
    bugs - of which there are many, as the latest crap with "truncate()" has
    shown us) a debugger doesn't much help. And the real problems are what I
    worry about. The rest is just details. It will get fixed eventually.

    I do realize that others disagree. And I'm not your Mom. You can use a
    kernel debugger if you want to, and I won't give you the cold shoulder
    because you have "sullied" yourself. But I'm not going to help you use
    one, and I wuld frankly prefer people not to use kernel debuggers that
    much. So I don't make it part of the standard distribution, and if the
    existing debuggers aren't very well known I won't shed a tear over it.

    Because I'm a bastard, and proud of it!

    Linus

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