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kbuild: handle multi-objs dependency appropriately

The comment in scripts/Makefile.build says as follows:

  We would rather have a list of rules like
        foo.o: $(foo-objs)
  but that's not so easy, so we rather make all composite objects depend
  on the set of all their parts

This commit makes it possible!

For example, assume a Makefile like this

  obj-m = foo.o bar.o
  foo-objs := foo1.o foo2.o
  bar-objs := bar1.o bar2.o

Without this patch, foo.o depends on all of
foo1.o foo2.o bar1.o bar2.o.
It looks funny that foo.o is regenerated when bar1.c is updated.

Now we can handle the dependency of foo.o and bar.o separately.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
This commit is contained in:
Masahiro Yamada 2014-08-19 16:34:20 +09:00 committed by Sascha Hauer
parent 0f1078d5cc
commit 22b3745f97
2 changed files with 13 additions and 6 deletions

View File

@ -367,16 +367,14 @@ cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps)
quiet_cmd_link_multi-m = LD [M] $@
cmd_link_multi-m = $(LD) $(ld_flags) $(LDFLAGS_MODULE) -o $@ $(link_multi_deps)
# We would rather have a list of rules like
# foo.o: $(foo-objs)
# but that's not so easy, so we rather make all composite objects depend
# on the set of all their parts
$(multi-used-y) : %.o: $(multi-objs-y) FORCE
$(multi-used-y): FORCE
$(call if_changed,link_multi-y)
$(call multi_depend, $(multi-used-y), .o, -objs -y)
$(multi-used-m) : %.o: $(multi-objs-m) FORCE
$(multi-used-m): FORCE
$(call if_changed,link_multi-m)
@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
$(call multi_depend, $(multi-used-m), .o, -objs -y)
targets += $(multi-used-y) $(multi-used-m)

View File

@ -162,6 +162,15 @@ dtc_cpp_flags = -Wp,-MD,$(depfile).pre -nostdinc \
modname-multi = $(sort $(foreach m,$(multi-used),\
$(if $(filter $(subst $(obj)/,,$*.o), $($(m:.o=-objs)) $($(m:.o=-y))),$(m:.o=))))
# Useful for describing the dependency of composite objects
# Usage:
# $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)
define multi_depend
$(foreach m, $(notdir $1), \
$(eval $(obj)/$m: \
$(addprefix $(obj)/, $(foreach s, $3, $($(m:%$(strip $2)=%$(s)))))))
endef
# Shipped files
# ===========================================================================