1 files changed, 89 insertions, 25 deletions
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index b0d067be739..4f5ff19b992 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -8,9 +8,17 @@ empty   :=
 space   := $(empty) $(empty)
 
 ###
+# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
+dot-target = $(dir $@).$(notdir $@)
+
+###
 # The temporary file to save gcc -MD generated dependencies must not
 # contain a comma
-depfile = $(subst $(comma),_,$(@D)/.$(@F).d)
+depfile = $(subst $(comma),_,$(dot-target).d)
+
+###
+# filename of target with directory and extension stripped
+basetarget = $(basename $(notdir $@))
 
 ###
 # Escape single quote for use in echo statements
@@ -55,6 +63,13 @@ as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
 	     -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
 	     else echo "$(2)"; fi ;)
 
+# as-instr
+# Usage: cflags-y += $(call as-instr, instr, option1, option2)
+
+as-instr = $(shell if echo -e "$(1)" | $(AS) >/dev/null 2>&1 -W -Z -o astest$$$$.out ; \
+		   then echo "$(2)"; else echo "$(3)"; fi; \
+	           rm -f astest$$$$.out)
+
 # cc-option
 # Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
 
@@ -73,14 +88,20 @@ cc-option-align = $(subst -functions=0,,\
 
 # cc-version
 # Usage gcc-ver := $(call cc-version, $(CC))
-cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
-              $(if $(1), $(1), $(CC)))
+cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
 
 # cc-ifversion
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
 cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \
                        echo $(3); fi;)
 
+# ld-option
+# Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both)
+ld-option = $(shell if $(CC) $(1) \
+			     -nostdlib -o ldtest$$$$.out -xc /dev/null \
+             > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi; \
+	     rm -f ldtest$$$$.out)
+
 ###
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
 # Usage:
@@ -109,40 +130,83 @@ objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
 ifneq ($(KBUILD_NOCMDDEP),1)
 # Check if both arguments has same arguments. Result in empty string if equal
 # User may override this check using make KBUILD_NOCMDDEP=1
-arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) )
+arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
+                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )
 endif
 
 # echo command. Short version is $(quiet) equals quiet, otherwise full command
 echo-cmd = $(if $($(quiet)cmd_$(1)), \
-	echo '  $(call escsq,$($(quiet)cmd_$(1)))';)
+	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
 
+# >'< substitution is for echo to work,
+# >$< substitution to preserve $ when reloading .cmd file
+# note: when using inline perl scripts [perl -e '...$$t=1;...']
+# in $(cmd_xxx) double $$ your perl vars
 make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
 
-# function to only execute the passed command if necessary
-# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file
-# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars
+# Find any prerequisites that is newer than target or that does not exist.
+# PHONY targets skipped in both cases.
+any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
+
+# Execute command if command has changed or prerequisitei(s) are updated
 #
-if_changed = $(if $(strip $(filter-out $(PHONY),$?)          \
-		$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \
-	@set -e; \
-	$(echo-cmd) $(cmd_$(1)); \
-	echo 'cmd_$@ := $(make-cmd)' > $(@D)/.$(@F).cmd)
+if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
+	@set -e;                                                             \
+	$(echo-cmd) $(cmd_$(1));                                             \
+	echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
 
 # execute the command and also postprocess generated .d dependencies
 # file
-if_changed_dep = $(if $(strip $(filter-out $(PHONY),$?)  \
-		$(filter-out FORCE $(wildcard $^),$^)    \
-	$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),     \
-	@set -e; \
-	$(echo-cmd) $(cmd_$(1)); \
-	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(@D)/.$(@F).tmp; \
-	rm -f $(depfile); \
-	mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd)
+if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
+	@set -e;                                                             \
+	$(echo-cmd) $(cmd_$(1));                                             \
+	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
+	rm -f $(depfile);                                                    \
+	mv -f $(dot-target).tmp $(dot-target).cmd)
 
 # Usage: $(call if_changed_rule,foo)
 # will check if $(cmd_foo) changed, or any of the prequisites changed,
 # and if so will execute $(rule_foo)
-if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?)            \
-			$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\
-			@set -e; \
-			$(rule_$(1)))
+if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
+	@set -e;                                                             \
+	$(rule_$(1)))
+
+###
+# why - tell why a a target got build
+#       enabled by make V=2
+#       Output (listed in the order they are checked):
+#          (1) - due to target is PHONY
+#          (2) - due to target missing
+#          (3) - due to: file1.h file2.h
+#          (4) - due to command line change
+#          (5) - due to missing .cmd file
+#          (6) - due to target not in $(targets)
+# (1) PHONY targets are always build
+# (2) No target, so we better build it
+# (3) Prerequisite is newer than target
+# (4) The command line stored in the file named dir/.target.cmd
+#     differed from actual command line. This happens when compiler
+#     options changes
+# (5) No dir/.target.cmd file (used to store command line)
+# (6) No dir/.target.cmd file and target not listed in $(targets)
+#     This is a good hint that there is a bug in the kbuild file
+ifeq ($(KBUILD_VERBOSE),2)
+why =                                                                        \
+    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
+        $(if $(wildcard $@),                                                 \
+            $(if $(strip $(any-prereq)),- due to: $(any-prereq),             \
+                $(if $(arg-check),                                           \
+                    $(if $(cmd_$@),- due to command line change,             \
+                        $(if $(filter $@, $(targets)),                       \
+                            - due to missing .cmd file,                      \
+                            - due to $(notdir $@) not in $$(targets)         \
+                         )                                                   \
+                     )                                                       \
+                 )                                                           \
+             ),                                                              \
+             - due to target missing                                         \
+         )                                                                   \
+     )
+
+echo-why = $(call escsq, $(strip $(why)))
+endif