[PATCH] uml kbuild: avoid useless rebuilds

- Fix some problems with usage of $(targets) (sometimes missing, sometimes
  used badly) that trigger partial rebuilds when doing a rebuild.

- At that purpose, also factor out some common code for symlinks creation.

- Fix a x86-64 build warning, caused by -L/usr/lib, which is anyway useless,
  and invalid in the x86-64 case.

Tested on x86_64 and x86.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/um/scripts/Makefile.rules b/arch/um/scripts/Makefile.rules
index 143f6fe..ea3c874 100644
--- a/arch/um/scripts/Makefile.rules
+++ b/arch/um/scripts/Makefile.rules
@@ -10,4 +10,18 @@ USER_OBJS := $(foreach file,$(USER_OBJS),$(obj)/$(file))
 $(USER_OBJS): c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) $(CFLAGS_$(notdir $@))
 
 quiet_cmd_make_link = SYMLINK $@
-cmd_make_link       = rm -f $@; ln -sf $(srctree)/arch/$(SUBARCH)/$($(notdir $@)-dir)/$(notdir $@) $@
+cmd_make_link       = ln -sf $(srctree)/arch/$(SUBARCH)/$($(notdir $@)-dir)/$(notdir $@) $@
+
+# this needs to be before the foreach, because targets does not accept
+# complete paths like $(obj)/$(f). To make sure this works, use a := assignment,
+# or we will get $(obj)/$(f) in the "targets" value.
+# Also, this forces you to use the := syntax when assigning to targets.
+# Otherwise the line below will cause an infinite loop (if you don't know why,
+# just do it).
+
+targets := $(targets) $(SYMLINKS)
+
+SYMLINKS := $(foreach f,$(SYMLINKS),$(obj)/$(f))
+
+$(SYMLINKS): FORCE
+	$(call if_changed,make_link)