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    SubjectRe: How to transfer memory from PCI memory directly to user space safely and portable?
    Date
    Followup to:  <20001126151120.V2272@parcelfarce.linux.theplanet.co.uk>
    By author: Philipp Rumpf <prumpf@parcelfarce.linux.theplanet.co.uk>
    In newsgroup: linux.dev.kernel
    >
    > I hope count isn't provided by userspace here ?
    >
    > > 1. What happens if the user space memory is swapped to disk? Will
    > > verify_area() make sure that the memory is in physical RAM when it returns,
    > > or will it return -EFAULT, or will something even worse happen?
    >
    > On i386, you'll sleep implicitly waiting for the page fault to be handled; in
    > the generic case, anything could happen.
    >

    That doesn't sound right. I would expect it to wait for the page to
    be brought in on any and all architectures, otherwise it seems rather
    impossible to write portable Linux kernel code.

    -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
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