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Date:      Thu, 21 Feb 2002 14:15:41 +0100
From:      Cliff Sarginson <csfbsd@raggedclown.net>
To:        FreeBSD-questions@FreeBSD.org
Subject:   Kernel loader
Message-ID:  <20020221131541.GA6721@raggedclown.net>

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Well, I tried this out in -hackers, and got a couple of mono-syllabic
replies, but no-one answered my question. So I will try it here.

The kernel loader code has mechanisms to implant dependencies in the
module code, e.g. if module A requires module B, then you can build
this knowledge into module A.

Now I do not believe that if you load module A, then module B is
automagically loaded as well. Looking at the program kldload it
is just a few lines that just invokes a system call to load the
module requested. I think the system call code should be in my
source tree somewhere but I am damned if I can find it.

What I was getting at is that in Linux they have this 'depmod'
setup that creates a dependency list, so that loading a module
should load all other required modules. I am looking for the
same functionality in FreeBSD. I do not believe it exists.

Can anyone confirm this, or refute it.

My second question was this.
It seems to me that the kernel module loading may have some 
sensitivity over the point at which it is loaded. I have reported
a bug in drm-kmod and my tests seem to show that it makes a
difference when a particular module (in this case "agp") is loaded
early on in the boot process via loader.conf, or later on by a shell
command in /usr/local/etc/rc.d. Is this likely to be expected ?
I got zero answers to this question.

If it does make a difference then I would be so bold as to say that
on-demand kernel loadable modules are not on-demand kernel loadable
modules if they cannot be loaded after the main boot process is
complete...and therefore you may as well build them into the kernel
in the first place.

Does anyone have any insight into this ?

Thanks.
-- 
Regards
   Cliff Sarginson -- <csfbsd@raggedclown.net>

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