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    SubjectRe: [PATCH] [request for inclusion] Realtime LSM
    On Thu, 2005-01-13 at 21:40 -0500, Paul Davis wrote:
    > >SCHED_FIFO and SCHED_RR are definitely privileged operations and you
    > this is the crux of what this whole debate is about. for all of you
    > people who think about linux on multi-user systems with network
    > connectivity, running servers and so forth, this is clearly a given.
    > but there is large and growing body of machines that run linux where
    > the sole human user of the machine has a strong and overwhelming
    > desire to have tasks run with the characteristics offered by
    > SCHED_FIFO and/or SCHED_RR. are they still "privileged" operations on
    > this class of linux system? what about linux installed on an embedded
    > system, with a small LCD screen and the sole purpose of running audio
    > apps live? are they still privileged then?

    I think yes, because their misuse can trivially take down the
    machine by definition. So it is still privileged in the context
    of that system.

    > i think there is room for debate, but its clear that in general,
    > SCHED_FIFO/SCHED_RR's "definite" status as privileged operations is
    > not clear. we are trying to find ways to provide access to it in ways
    > that don't conflict with the other categories of linux systems where
    > it clearly needs to be off-limits to unprivileged users.

    In such a system, sure you could make allowances by elevating
    privileges or what have you.

    I guess the tricky part is exactly how to make these allowances. I've
    joined the thread too late (and don't have the knowledge) to really get
    into that... but I just wanted to be clear that watering down SCHED_RR
    and SCHED_FIFO basically just makes them no good to anyone.

    I personally can't see how a scheduling policy can allow deterministic
    access to the CPU without being a privileged operation. If you don't
    need deterministic access to the scheduler, then let's talk about why
    SCHED_OTHER isn't good enough. If you do, then we're talking about
    security access I think.

    Nick - Yahoo! Mobile

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