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    SubjectRe: sysconf (was Re: RLIM_INFINITY inconsistency between archs)
    Linus Torvalds wrote:
    > On 28 Jul 2000, Ulrich Drepper wrote:
    > > Linus Torvalds <> writes:
    > >
    > > > There is only a stupid push to try to be more generic than anybody
    > > > actually needs! It makes glibc slower and bigger than it needs to be, and
    > > > quite frankly I don't see the point of having a system call that returns
    > > > the value "32".
    > >
    > > It will not return 32 in all cases, that's the whole point. I will
    > > save this mail and send it to all the people who complain about this.
    > > There are lots of people who need larger numbers of groups. If you
    > > don't need such a large number doesnot mean nobody needs it.
    > PLEASE save the mail.
    > But even more, please READ the mail too. Look at my suggestion. And when
    > you send the mail out to somebody who complains about NRGROUPS, then send
    > out the mail in ENTIRETY, and explain to those people why you continually
    > ignore my suggestions even though they obviously fix the problem.
    > I'm damn sick and tired of you blaming the kernel for your own stupidity
    > and incompetence.

    Now, the maximum number of groups is something that the kernel could
    potentially change and that *would* affect user space. Similar to the
    maximum number of files. Now... we have a perfectly good way to export
    constants like that to user space, i.e. the sysctl (/proc/sys)
    mechanism. This gives a couple of options:

    a) The kernel implements such a sysctl, readonly at least for now, glibc
    uses it, if available;
    b) glibc doesn't do anything for now, if we change NGROUPS we export it
    via sysctl and glibc will need to be updated then;
    c) we reserve a namespace point, say /proc/sys/kernel/ngroups, and glibc
    uses it, if available. If we ever change NGROUPS *then* we add it to
    the kernel;
    d) glibc may have a /etc/sysconf file, which can look like:

    __SC_NGROUPS 32

    ... in the future, it may look like ...

    __SC_NGROUPS /proc/sys/kernel/ngroups


    <> at work, <> in private!
    "Unix gives you enough rope to shoot yourself in the foot."

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