Re: devd limitations / automounting removable storage

From: Robert Watson (rwatson_at_freebsd.org)
Date: 09/18/03

  • Next message: M. Warner Losh: "Re: devd limitations / automounting removable storage" 
    Date: Thu, 18 Sep 2003 14:18:54 -0400 (EDT)
To: "M. Warner Losh" <imp@bsdimp.com>

    On Thu, 18 Sep 2003, M. Warner Losh wrote:

    > In message: <Pine.NEB.3.96L.1030918104650.60612B-100000@fledge.watson.org>
    > Robert Watson <rwatson@freebsd.org> writes:
    > : For ifnet events, we can use routing sockets. I don't know that we have
    > : GEOM events as yet. One reason to separately handle GEOM from devfs would
    > : be that GEOM "objects" tend to be storage devices or related notions,
    > : whereas devfs entries could be any number of things.
    >
    > While this is true, one can ask a /dev entry what kind of object it is.
    > Since one can do that, one can construct filters that will only do
    > things for storage objects.

    Opening a device to ask it what it might be is generally a bad idea -- you
    can block other consumers from using the device (and related devices),
    cause a variety side-effects, etc. Also, I'm not clear that you can get a
    useful result using open/fstat/stat/ioctl to figure out what something is
    without apriori knowledge of device numbers, and even then the utility is
    limited. If you have a network layer announcement "Hey, this interface
    arrived", then there's no question that it's a network interface.

    > I worry about putting these new event streams at the wrong level and/or
    > having too many of them making it hard to know what the appropriate
    > level/event to do something at is.

    Agreed.

    Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
    robert@fledge.watson.org Network Associates Laboratories

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