Quick build of stripped-down kernel

[b. f.]

On 11/25/11, Thomas Mueller <mueller6727 at bellsouth.net> wrote:
> from "b. f." <bf1783 at googlemail.com>:
>
>> If you are going to build most of the modules, but only want to
>> exclude a few, then add the directories of the modules to be excluded
>> (relative to /usr/src/sys/modules) to WITHOUT_MODULES, for example in
>> /etc/make.conf. If you are only going to build a few modules, and want
>> to exclude the majority of the modules, then add the directories of
>> the modules that are to be built to MODULES_OVERRIDE.  For no modules
>> at all, set NO_MODULES.  See /usr/src/sys/modules/Makefile and
>> /usr/src/sys/conf/kern.post.mk for details. You may also save some
>> time by using one of your faster machines to build the OS for the
>> slower machines.
>
> Suppose you want to build more than one kernel so as to be able to choose at
> boot time.
>
> Then you might not want to build modules redundantly.  So how would you make
> the modules from /boot/kernel accessible when booting /boot/kernel2?
>

If the kernel versions were compatible, and the set of modules were
the same, I suppose you could set MODULES_WITH_WORLD and
KODIR=/boot/modules during buildworld and installworld, to build the
modules as part of buildworld and install them in /boot/modules during
installworld, rather than in /boot/kernel or /boot/kernel2.  Then you
could build and install both of your kernels with NO_MODULES, as
previously discussed, and with your  different choices of KODIR for
each kernel.  Because /boot/modules is part of the default module_path
defined in /boot/defaults/loader.conf, the modules ought to load as
usual for either kernel.  If you wanted to place them in a different
directory, you could alter KODIR during buildworld and installworld,
and add the directory to module_path in /boot/loader.conf.  I haven't
tested this, but I think that it will work, and I'd be interested to
hear whether it does. There are of course alternative methods.

b.