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    SubjectRe: devfs vs udev, thoughts from a devfs user
    On Wed, Feb 11, 2004 at 10:44:10AM +0100, Helge Hafting wrote:
    > Sure. Completely random device numbers will make this demand loading of
    > device drivers impossible. Either it won't happen (all numbers won't be
    > completely random, although they may get more dynamic than today) or
    > module loading based on device node opening will be deprecated.

    It could be made to work. You could have a magic device number, say
    (255,255), which means "unloaded device driver", which causes a
    hotplug callout, and a SIGSTOP sent to the process that tried the
    open. The userspace program would then be responsible for loading the
    relevant device driver, converting the /dev file to the correct
    dynamic major/minor number, and then sending a SIGCONT to the process,
    which would then either restart the open() or the open() would return
    -EAGAIN.

    It would be kinda hairy, in that the kernel would need to know whether
    or not userspace had accepted responsibility for handling these calls
    (if it didn't open() would just return -ENODEV as it does today). So
    it might not be worth doing, but if people really cared about it, it
    could indeed be done.

    - Ted
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