Date: Thu, 18 Sep 2003 14:18:54 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-arch@freebsd.org Subject: Re: devd limitations / automounting removable storage Message-ID: <Pine.NEB.3.96L.1030918141648.1604D-100000@fledge.watson.org> In-Reply-To: <20030918.121507.32721201.imp@bsdimp.com>
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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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