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To: Robert Watson <rwatson@freebsd.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Fri, 09 Jul 2004 10:32:15 EDT."
             <Pine.NEB.3.96L.1040709102423.60816K-100000@fledge.watson.org> 
Date: Fri, 09 Jul 2004 16:36:05 +0200
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Sender: phk@critter.freebsd.dk
cc: Brian Somers <brian@Awfulhak.org>
cc: arch@freebsd.org
Subject: Re: [RFC] kldunload -f argument. 
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In message <Pine.NEB.3.96L.1040709102423.60816K-100000@fledge.watson.org>, Robert Watson writes:
>
>On Fri, 9 Jul 2004, Brian Somers wrote:
>
>> > I'm not sure I see any real-world application for this ?  Can you give an
>> > example ?  Why would you load a module and not use it ?
>> 
>> I can't think of any non-development-environment reasons unless there's
>> room for modules being loaded early to be able to make assumptions about
>> their environment at ACTIVATE time (such as a root filesystem being
>> available).
>
>We actually have an example in the form of snd_driver, which forces all
>the sound modules to load, with the intent that when you unload, the
>attached ones are left running.  We also have a lot of functionality
>compiled into GENERIC that many people don't use or use only infrequently
>-- when that functionality is compiled into modules, we frequently
>automatically load modules during a file system mount, netgraph pieces,
>etc.  When they're no longer in use, they hang around.  In a world where
>we consistently load modules on demand, and those modules remain idle
>after use, it would be somewhat nice to be able to simply say "Ok, modules
>no longer needed, please unload yourselves".

Yes, but I found out why this is troublesome:  Modules != KLD.

One KLD may contain multiple modules.

I think that if we need activate/quiesce on a per module interface then we
should not do it with KLD granularity.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.