From: Jeff Garzik <jgarzik@pobox.com>

I've seen this patch floating around.  Not sure the origin, but it's 
surfaced on lkml and also when I was poking around handhelds.org CVS for
iPAQ patches:  on non-PCs, particularly system-on-chip devices but not
just there, you have a custom "platform bus" that is the root of pretty 
much all other devices and buses.

It's something I wanted to make sure people didn't forget; to make sure 
the legacy_bus didn't get "legacied out of existence."  ;-)