-objs:=$(obj)/mainboard/$(MAINBOARDDIR)/static.o
-initobjs:=
-drivers:=
-smmobjs:=
-crt0s:=
-ldscripts:=
-types:=obj initobj driver smmobj
-includemakefiles=$(foreach type,$(2), $(eval $(type)-y:=)) $(eval subdirs-y:=) $(eval -include $(1)) $(if $(strip $(3)),$(foreach type,$(2),$(eval $(type)s+=$$(patsubst src/%,$(obj)/%,$$(addprefix $(dir $(1)),$$($(type)-y)))))) $(eval subdirs+=$$(subst $(PWD)/,,$$(abspath $$(addprefix $(dir $(1)),$$(subdirs-y)))))
-evaluate_subdirs=$(eval cursubdirs:=$(subdirs)) $(eval subdirs:=) $(foreach dir,$(cursubdirs),$(eval $(call includemakefiles,$(dir)/Makefile.inc,$(types),$(1)))) $(if $(subdirs),$(eval $(call evaluate_subdirs, $(1))))
+# must come rather early
+.SECONDEXPANSION:
+
+$(obj)/config.h:
+ $(MAKE) oldconfig
+
+# Add a new class of source/object files to the build system
+add-class= \
+ $(eval $(1)-srcs:=) \
+ $(eval $(1)-objs:=) \
+ $(eval classes+=$(1))
+
+# Special classes are managed types with special behaviour
+# On parse time, for each entry in variable $(1)-y
+# a handler $(1)-handler is executed with the arguments:
+# * $(1): directory the parser is in
+# * $(2): current entry
+add-special-class= \
+ $(eval $(1):=) \
+ $(eval special-classes+=$(1))
+
+# Clean -y variables, include Makefile.inc
+# Add paths to files in X-y to X-srcs
+# Add subdirs-y to subdirs
+includemakefiles= \
+ $(foreach class,classes subdirs $(classes) $(special-classes), $(eval $(class)-y:=)) \
+ $(eval -include $(1)) \
+ $(foreach class,$(classes-y), $(call add-class,$(class))) \
+ $(foreach class,$(classes), \
+ $(eval $(class)-srcs+= \
+ $$(subst $(top)/,, \
+ $$(abspath $$(subst $(dir $(1))/,/,$$(addprefix $(dir $(1)),$$($(class)-y))))))) \
+ $(foreach special,$(special-classes), \
+ $(foreach item,$($(special)-y), $(call $(special)-handler,$(dir $(1)),$(item)))) \
+ $(eval subdirs+=$$(subst $(CURDIR)/,,$$(abspath $$(addprefix $(dir $(1)),$$(subdirs-y)))))
+
+# For each path in $(subdirs) call includemakefiles
+# Repeat until subdirs is empty
+evaluate_subdirs= \
+ $(eval cursubdirs:=$(subdirs)) \
+ $(eval subdirs:=) \
+ $(foreach dir,$(cursubdirs), \
+ $(eval $(call includemakefiles,$(dir)/Makefile.inc))) \
+ $(if $(subdirs),$(eval $(call evaluate_subdirs)))