documenting loadable kernel modules

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

I am writing one- to three- line descriptions for all kernel modules. I 
see at least 75. I have some questons about this:

1) How to select what modules are built?

FreeBSD builds all kernel modules even for features also available in 
kernel. It offers make variables MODULES_OVERRIDE (to select modules by 
module directory to build) and WITHOUT_MODULES (to list modules to 
exclude).

Anything like that for NetBSD?

I think all modules are built unless they are limited by architecture or 
are examples or a few other make variables.

Some NetBSDs have around 35 out of available 75 kernel modules. (I know 
several aren't built at all.) It looks like most of these are architecture 
specific.


2) And what is purpose of building modules when support is already 
provided? (A few examples follow.)

Why mfs.o when mount_mfs works fine?

Why is wi_pcmcia.o built (at least on i386)?

Why powernow.o on i386?

(My only answers are: to verify the module build works and to provide a 
module just in case using custom kernel.)


3) What platforms don't support LKM? I see some ports have LKM option and 
some don't. But even some that don't still have lkm device. I think only 
evbppc doesn't support LKMs.


4) Why no pci or pcmcia LKMs on amd64?


5) Any comment about secmodel_bsd44 LKM? I know it is not built at this 
time.


6) Does the dummy_pci have any purpose? Or why is it installed when other 
examples aren't built?


7) I see MKPF, MKIPFILTER, and MKPUFFS. Where are these documented that 
these define if modules are built or not?




  Jeremy C. Reed