[PATCH v2 1/5] ARM: Broadcom: Unconditionally build arch/arm/mach-bcm

[Russell King - ARM Linux]

On Sat, Jul 27, 2013 at 12:28:09AM +0200, Domenico Andreoli wrote:
> I've got the point but didn't fully understand why would be so wrong to
> walk one more subdir even if nothing is going to be built.

Consider what would happen if we decended the 61 mach- subdirectories
on every build run when only one was really required.  Even though
kbuild tries to be fast, there's still a non-zero amount of time
involved with finding out there's nothing to be done - and you
will still end up generating a built-in.o file even though there's
no other objects, which will then also be included in the final
link - again, adding to the work which has to be done.