if_tun module doesn't autoload if opening /dev/tunN

[Paul Goyette <paul%whooppee.com@localhost>]

According to the tun(4) man page, you can create an interface "by using 
the ifconfig(8) create command" and this works just fine.  The man page 
goes on to say "An open() call on /dev/tunN, will also create a network 
interface..." but this does not work.

I think this is because the code in sys/miscfs/specfs/spec_vnops.c 
assumes that the module name is the same as the device name, ie it 
expects that /dev/tunN will be handled by module tun.kmod  However, the 
module is actually named if_tun.kmod so it never gets loaded, and the 
open() fails.

I can see a couple of ways to "fix" this:

	1. Rename the module (with all appropriate updates to the
	   sets lists in src/distrib/sets/lists), or
	2. Add code to spec_vnops.c to try loading module if_xxx if the
	   autoload of module xxx fails.

Comments?  Preferences?  Any other options I haven't yet seen?


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