Re: kern/41668: MONOLITHIC should probably also be included in HEAD builds

[Alan Barrett <apb%cequrux.com@localhost>]

On Thu, 16 Jul 2009, ad%NetBSD.org@localhost wrote:
> The monolithic kernel an aid for people developing core kernel code,
> compiling their own kernels, and generally playing about in areas where one
> can shoot oneself in the foot rather easily.  I have never had the need for
> it but I can see the utility.

I'd add another class of users for whom the MONOLITHIC kernel is likely
to be desirable: users who build and install -current.

> When considered in the frame of a NetBSD release it offers nothing. 

A counter argument is that the modular framework offers no advantages
over a monolithic kernel.  No less source code, no less disk space
used, more difficult upgrades.  I still don't see who is supposed to
be helped by modular kernels: People with embedded hardware and small
memory -- Why can't they build custom kernels?  People who want all
possible features to be available whether they use them or not and have
enough memory for that -- Why can't they use a kernel with everything?
People who want to use third party closed source modular drivers for
proprietary hardware -- Why can't they do much the same using third
party closed source object files to be linked into a custom non-modular
kernel?

> Releases are all about a shipped product for end users ... unless the
> landscape has changed so dramatically that releases are all about us
> hackers and our toys, which would be a desperately sad state of affairs.

I agree with that point.

However, -current is not a release, and we don't have a good way of
updating modules at the same time as updating a kernel, so the risk
of module mismatches is still much too high for comfort.  I can see
that the decision to migrate to modular kernels has been made, even if
I don't like it, and it's fine to remove the MONOLITHIC kernel from
the default build of netbsd-6 when that is branched.  But please keep
MONOLITHIC in -current, at least until such time as people are no longer
afraid of getting hurt by a modular kernel with missing or mismatched
modules.

--apb (Alan Barrett)