Re: [PARPORT] libieee1284 automatically loads ppdev, lp?

From: Tim Waugh (
Date: Tue Feb 25 2003 - 11:40:43 EST

  • Next message: Blaise Gassend: "Re: [PARPORT] Bidirectional access to parallel port (JAVA)"

    On Tue, Feb 25, 2003 at 08:05:56AM -0800, Gora Mohanty wrote:

    > I am trying to use libiee1284 routines to do data acquisition over a
    > dedicated parallel port, and I would like to make sure that nothing else
    > on the system is trying to concurrently talk on the parallel port.
    > It seems that accessing /dev/parport0 automatically loads the modules
    > parport, parport_pc, lp and ppdev. Why are the last two loaded?

    ppdev is the driver that makes /dev/parport0 work; you want that loaded.

    > Is it possible to specify that they not be loaded? I was thinking
    > that the loading of lp, etc. was specified via /etc/modules.conf,
    > but mine has no entries for these, except for parport_pc. I am using
    > Redhat Linux 7.3 on an x86 box.

    The libieee1284 library accesses /dev/lp0 in order to provoke the
    low-level driver (parport_pc) into being loaded; it needs to find out
    what ports are available to use, and it does this via /proc. The
    entries in /proc aren't populated until parport_pc is loaded.

    Why is lp causing you problems?

    It sounds to me like F1284_EXCL is exactly what you are after. Are
    you using it?


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