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    From
    SubjectRe: [PATCH] Futexes IV (Fast Lightweight Userspace Semaphores)
    Date
    Followup to:  <Pine.LNX.4.33.0203081532550.4421-100000@penguin.transmeta.com>
    By author: Linus Torvalds <torvalds@transmeta.com>
    In newsgroup: linux.dev.kernel
    >
    > You don't understand. This has nothing to do with lock holders, or
    > anything else.
    >
    > I'm saying that we map in a page at a magic offset (just above the stack),
    > and that page contains the locking code.
    >
    > For 386 CPU's (where only UP matters), we can trivially come up with a
    > lock that doesn't use cmpxchg8b and that isn't SMP-safe. It might even go
    > into the kernel every time if it has to - ie it _works_, it just isn't
    > optimal.
    >

    Okay, I'll say it and be impopular...

    Perhaps it's time to drop i386 support?

    It seems to me that the i386 support has been around mostly on a
    "until we have a reason to do otherwise" basis, but perhaps this is
    the reason?

    There certainly are enough little, nagging reasons... CMPXCHG, BSWAP,
    and especially WP...

    -hpa
    --
    <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
    "Unix gives you enough rope to shoot yourself in the foot."
    http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com>
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