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    SubjectRe: [PATCH 1/1] LinuxPPS: Pulse per Second support for Linux
    On Mon, Feb 19, 2007 at 06:56:20PM -0800, H. Peter Anvin wrote:

    > It's not a precondition for a file descriptor, either. There are plenty
    > of ioctl-only device drivers in existence.
    > Furthermore, a file descriptor doesn't imply a device entry. Consider
    > pipe(2), for example.
    > As far as the kernel is concerned, a file handle is a nice, uniform
    > system for providing communication between the kernel and user space.
    > It doesn't matter if one can read() or write() on it; it's perfectly
    > normal to support only a subset of the normal operations.

    The problem is that sometimes you cannot have a filedescriptor at
    all. Think about a PPS source connected with a CPU's GPIO pin. You
    have no filedes to use and defining one just for a PPS source or for a
    class of PPS sources, I think, is a non sense.

    RFC simply doesn't consider the fact that you can have a PPS source
    __without__ a filedes connected with, and a single filedes is
    considered __always__ connected with a single PPS source.




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