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    SubjectRe: udev and devfs - The final word
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    On Thu, 2004-01-01 at 07:34, Rob Landley wrote:

    > Fundamental problem: "Unique" depends on the other devices in the system. You
    > can't guarantee unique by looking at one device, more or less by definition.

    Of course.

    > Combine that with hotplug and you have a world of pain. Generating a number
    > from a device is just a fancy hashing function, but as soon as you have two
    > devices that generate the same number independently (when in separate
    > systems) and you plug them both into the same system: boom.

    A solution would have to deal with collisions.

    > Of course the EASY way to deal with collisions is to just fail the hash thingy
    > in a detectable way, and punt to some kind of udev override. So if you yank
    > a drive from system A, throw it in system B, try to re-export it NFS, and
    > it's not going to work, it TELLS you.

    No no no. Nothing this complicated. No punting to udev.

    > Solve 90% of the problem space and have a human deal with the exceptions. How
    > big's the unique number being exported, anyway? (If it's 32 bits, the
    > exceptions are 1 in 4 billion. It may never be seen in the wild...)

    Device numbers are 64-bit now.

    Rob Love


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