Date: Sat, 11 Dec 1999 13:49:16 -0800 (PST) From: Archie Cobbs <archie@whistle.com> To: jkh@zippy.cdrom.com (Jordan K. Hubbard) Cc: abial@webgiro.com, freebsd-current@FreeBSD.ORG Subject: Re: Modules and sysctl tree Message-ID: <199912112149.NAA71033@bubba.whistle.com> In-Reply-To: <81199.944909403@zippy.cdrom.com> from "Jordan K. Hubbard" at "Dec 11, 1999 02:50:03 am"
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Jordan K. Hubbard writes: > > I think the latter. In 'theory' there should be no discernable > > difference between functionality from a KLD vs. the same functionality > > compiled directly into the kernel. > > Only in theory, of course. :) > > As Andrzej has already pointed out, modules can also be loaded and > unloaded, creating a sysctl space where things enter and leave > dynamically. Let's say I'm somebody who creates a nifty little GUI > sysctl editor for the CLI-challenged and, because it's time-consuming > to build a form with fields for all the relevant sysctl variables, I > take the obvious shortcut of parsing the output of `sysctl -A' once at > startup time and then dealing with the individual field callbacks > thereafter. On my "classic" system with a config-generated kernel, > this works just fine and my GUI front-end for sysctl is eventually > declared "useful enough" that I start handing it around. Then > somebody who actually loads and unloads klds tries to use it, and > results (needless to say) are no longer quite in alignment with > expectations. :) Just a hypothetical scenario, of course, but > I simply wanted to make the point that "no discernable difference" > might be hard to achieve for certain values of discernment. I think sysctl nodes appearing and disappearing falls into the same category as /dev files appearing and disappearing -- it's a natural thing to do in this day of dynamic devices, etc. but some programs were written with an implicit assumption that that would never happen. In other words, it's not a problem specific to KLD's .. but it's still a problem :-) -Archie ___________________________________________________________________________ Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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