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    SubjectRe: [ANNOUNCE] udev 0.1 release


    Lars Marowsky-Bree wrote:

    >On 2003-04-11T15:30:21,
    > Steven Dake <sdake@mvista.com> said:
    >
    >
    >
    >>There is no "spec" that states this is a requirement, however, telecom
    >>customers require the elapsed time from the time they request the disk
    >>to be used, to the disk being usable by the operating system to be 20 msec.
    >>
    >>
    >
    >Heh. Yes, I've read that spec, and some of it involves some good crack smoking
    >;-) The current Linux scheduler will make that rather hard for you, you'll
    >need hard realtime for such guarantees.
    >
    Its quite easy to do if you are not dependent upon spawning an entire
    process to execute the insertion and creation even of the device node.

    >
    >
    >
    >>Its even more helpful for their applications if the call that hotswap
    >>inserts blocks until the device is actually ready to use and available
    >>in the filesystem. Another requirement of any system that attempts to
    >>replace devfs would be this capability (vs constantly checking for the
    >>device in the filesystem).
    >>
    >>
    >
    >Uh. Can you please clarify?
    >
    >You want open(/dev/not_there_yet) to block until /dev/not_there_yet is
    >inserted? But if it is not inserted, the device file does not exist yet, so
    >the open() will simply return a ENOENT.
    >
    >The application (or a library, providing this capability you want) could
    >interact with the hotplug subsystem to be notified when this device is
    >inserted.
    >
    >
    >Sincerely,
    > Lars Marowsky-Brée <lmb@suse.de>
    >
    >
    >

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