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Date:      Fri, 15 Sep 2006 22:11:53 -0400
From:      "David Wassman" <opensrc.root@gmail.com>
To:        "Lowell Gilbert" <freebsd-questions-local@be-well.ilk.org>
Cc:        FreeBSD-Questions Mailing List <freebsd-questions@freebsd.org>
Subject:   Re: Device Drivers and Kernel Modules
Message-ID:  <b96c39670609151911u13f3c105v3625e2892a79adea@mail.gmail.com>
In-Reply-To: <441wqqlc97.fsf@be-well.ilk.org>
References:  <b96c39670609021308o766fe72frd9833164630a930a@mail.gmail.com> <441wqqlc97.fsf@be-well.ilk.org>

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Lowell,

Thanks for the reply. Sorry about the belated gratitude. I haven't checked
the account in a while and simply forgot I posted the question. I think I
got confused in my memory. Now what I think I read was about filesystem
kernel modules. From my understanding these could be automatically loaded
through the mount command. At least, thats the author's claim in FreeBSD
Unleashed.

Just to be more specific this inquiry is NOT for a server. It is my
experimental desktop at home. Servers I would agree have no need to be
convenient in swapping hardware. But I do switch out hardware on the system
in question occasionally and was really just curious if there is a drawback
between the drivers in the kernel opposed to loaded kernel modules.

Thanks again

David Wassman

On 9/5/06, Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> wrote:
>
> "David Wassman" <opensrc.root@gmail.com> writes:
>
> > I am trying to figure out which would be best, to load all the device
> > drivers through compiling them into the kernel or to load them at boot
> > through loader.conf.
> >
> > I would think that loader.conf would be more convenient as changing
> hardware
> > wuld not require a rebuild of the kernel. Is there a draw back to
> loading
> > devices this way other than a longer boot up time (which should not be
> an
> > issue as the system is 24-7)?
>
> There is little difference for your purposes.
>
> > I have also heard that loading modules through the loader.conf saves on
> RAM
> > performance as the module in question is not loaded into memory until it
> is
> > used as opposed to being loaded with the kernel. If this makes no sense,
> i
> > appologize. I remember reading it somewhere on a mailing list several
> years
> > ago and can't find the reference anymore. From memory it stated modules
> such
> > as cd9660 could be loaded through entering CD9660_load="YES" in
> > loader.confand that it would not be used in memory until a cd was
> > mounted. I am
> > assuming this is true (if it is) for other modules as well.
>
> It isn't true at all.  Loading a module really does load it into memory.
>
> --
> Lowell Gilbert, embedded/networking software engineer, Boston area
>                 http://be-well.ilk.org/~lowell/
>



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