can't build modules after clean for powerpc

[Darren Hart <dvhart@linux.intel.com>]

According to the Makefile comments and
Documentation/kconfig/makefile.txt, make clean should leave enough
intact to build modules with:

###
# Cleaning is done on three levels.
# make clean     Delete most generated files
#                Leave enough to build external modules

The following line in the arch/powerpc/Makefile prevents that from working:

KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o

External module compilation fails to link as it can't find
arch/powerpc/lib/crtsavres.o.

It appears from the make logs that crtsavres.o is linked in to
built-in.o, and thus vmlinux. If that is the case, it doesn't seem like
crtsavres.o should need to be singled out. What am I missing here?

If I comment it out:

#KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o

my example module builds successfully.

If it is necessary, then we need a means to instruct the top level
makefile to not delete it during "clean". Is there such a directive?

KBUILD_CLEAN_EXCLUDE_MODULES or something?

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel