Why not the prod_id strings themselves?

a) They may contain all sorts of strange and difficult to handle characters,
   like " ".

b) It's impossible to pass multiple strings to userspace.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>