Date: Mon, 24 Jan 2005 20:46:44 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: rwatson@freebsd.org Cc: pete@altadena.net Subject: Re: Devd event from GEOM? Message-ID: <20050124.204644.32725683.imp@bsdimp.com> In-Reply-To: <Pine.NEB.3.96L.1050124095359.63183B-100000@fledge.watson.org> References: <20050124055703.GA40104@users.altadena.net> <Pine.NEB.3.96L.1050124095359.63183B-100000@fledge.watson.org>
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In message: <Pine.NEB.3.96L.1050124095359.63183B-100000@fledge.watson.org>
Robert Watson <rwatson@freebsd.org> writes:
:
: On Sun, 23 Jan 2005, Pete Carah wrote:
:
: > Geom doesn't feed node-creations to devd in 5.3. This would be VERY
: > useful for letting ordinary non-programmer users access pen drives,
: > among other things (floppies come to mind too...). (or mount e.g. a pen
: > drive as part of an authentication system where no-one is yet logged in,
: > so can't manually mount...)
: >
: > umass0 comes in to devd, but this isn't useful for use in "mount". One
: > needs the disk device nodes. I suppose one *could* parse dmesg for the
: > info (or maybe sysctl) but that smacks of a serious kluge. (not to
: > mention that the slice table isn't represented in dmesg anyhow, and
: > practically nothing is in sysctl...)
: >
: > Does this yet happen in any later version (RELENG_5 or HEAD)? If not,
: > is there anyone planning or working on it?
: >
: > It *does* work in Solaris and IRIX, (I know - we aren't them...) I
: > don't know about any Linux or other *BSD version either.
: >
: > Geom is modular enough that this shouldn't be difficult...
:
: I used the attached patches do announce storage device arrival on my
: notebook so that I can do auto-mounting of USB storage. There appears to
: be some disagreement regarding layering: my opinion has generally been
: that since there are multiple layers involved, we should announce both the
: layer and the device, for example:
:
: Network stack says "ifnet fxp0 arrived"
:
: separately from:
:
: /dev says "/dev/net/fxp0 arrived"
and newbus says fxp0 arrived :-)
: Since they constitute different "things" with quite different management
: properties. This also provides additional contextual information: rather
: than devd having to guess what type of object a device node is using name
: matching, by learning about it through geom or the network stack, it knows
: what kind it is up front in a strong way.
While I tend to agree, I do think that GEOM is the wrong layer to
announce things from. The more correct layer would be /dev, since you
are again assuming that a GEOM that's created with name foo is
accessible via /dev/foo.
Warner
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