Subject: Re: LKM support
To: None <current-users@NetBSD.ORG>
From: Jim Wise <jw250@columbia.edu>
List: current-users
Date: 11/06/1996 22:58:55
On Wed, 6 Nov 1996, Frank van der Linden wrote:
> Quoting Matthias Scheler,
>
> > Michael Graff said:
> > > IMHO, mount should try to mount, and if the FS isn't compiled in, try to
> > > modload it, then mount again. That would make everything happy, no? :)
>
> > > And this functionality should be put into a library.
>
> > Hmmm... some kind of if-a-kernel-feature-is-not-there-try-to-modload-it-call?
> > Not bad... but how should the interface for this look like?
>
> FreeBSD loads LKMs (if necessary) from the different mount_xxx programs,
> you might want to look at their interface (vfsent, vfsload, vfsisloadable).
Irix (don't you shudder at me, young man) has a neat way of handling this.
When you load a module, using ml, you can use `ml ld ...' to load a
module, which is the same as modload under NetBSD, or you can use
`ml reg ...' to `register' a module. A registered module is duly noted by
the kernel, but is not loaded until it is used. This makes it possible,
for example, to have a kernel which can use any supported device, but
which is hardly larger than a kernel stripped to just those devices which
are present.
IMHO, this is a _much_ better solution than having the kernel go looking
for LKMs as needed, as it allows explicit control over which LKMs the
kernel can load, and also allows ldconfig-style shortcuts to be built for
registered modules
--
Jim Wise
System Administrator
GSAPP, Columbia University
jim@santafe.arch.columbia.edu
http://www.arch.columbia.edu/~jim
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