MODULAR: Module extensions

[Julio M. Merino Vidal <jmmv84%gmail.com@localhost>]

Hello,

I see that the new modular framework still uses .o as the extensions  
for modules.  In my opinion, these are "suboptimal" because they are  
confusing.  Extensions are something for the user, not the computer,  
so they should be descriptive enough to be useful.  When I see ".o",  
I think of a temporary compilation file that can be deleted, not  
something that should be kept around for proper system operation.

Could we rename the new modules to have a different extension?  One  
possibility could be .ko as used in Linux, or .kmod to match the name  
of bsd.kmod.mk.  If we want to be descriptive, .kmod is better as it  
clearly states it is a kernel module, not a kernel object (which  
could also be thought as of something related to the compilation).

Slightly related to this: with the current bsd.kmod.mk and .o  
extensions, it is impossible to build a foo.o kernel module if any of  
its source files is named foo.c.  E.g. sys/modules/example is  
currently unbuidable:

> nbmake-i386
nbmake: Graph cycles through example.o
nbmake: don't know how to make example.4. Stop

nbmake: stopped in /Volumes/NetBSD/src/sys/modules/example
>

bsd.kmod.mk will try to compile foo.c to foo.o and then try to link  
all .o files into foo.o. Oops, but foo.o is already defined to be  
foo.c's object, so we have a dependency loop.  Having a different  
extension for the final file easily fixes this.

Objections about the change to .kmod?

Thanks.