From owner-freebsd-current Sat Dec 11 13:49:52 1999 Delivered-To: freebsd-current@freebsd.org Received: from bubba.whistle.com (bubba.whistle.com [207.76.205.7]) by hub.freebsd.org (Postfix) with ESMTP id E4AAF14E3C for ; Sat, 11 Dec 1999 13:49:50 -0800 (PST) (envelope-from archie@whistle.com) Received: (from archie@localhost) by bubba.whistle.com (8.9.2/8.9.2) id NAA71033; Sat, 11 Dec 1999 13:49:16 -0800 (PST) From: Archie Cobbs Message-Id: <199912112149.NAA71033@bubba.whistle.com> Subject: Re: Modules and sysctl tree In-Reply-To: <81199.944909403@zippy.cdrom.com> from "Jordan K. Hubbard" at "Dec 11, 1999 02:50:03 am" To: jkh@zippy.cdrom.com (Jordan K. Hubbard) Date: Sat, 11 Dec 1999 13:49:16 -0800 (PST) Cc: abial@webgiro.com, freebsd-current@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG 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