Messages in this thread Patch in this message | | | Date | Wed, 5 Jul 2006 11:30:56 +0200 | From | Sam Ravnborg <> | Subject | Re: [KBUILD] optionally print cause of rebuild (#2) |
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Hi Milton.
On Wed, Jul 05, 2006 at 02:01:26AM -0500, Milton Miller wrote: > Al wanted to see why Kbuild wanted to build files, to help debug > Makefiles or dependency chains. > > Here is my second draft, with with whitespace handled by strip. It > also now considers cmd_$@ before the targets variable because its > both what the rules do and because the toplevel doesn't use targets. > It still always prints the non-existing $^ stuff that only > if_changed_dep uses. I like the idea and I have played around with it a bit before. To keep noise level down the "why got it rebuild" info should be on same line as the CC command and to trigger it increasing verbose level to 2 seems more natural.
Following patch does this. The patch contains a few clean-ups to make the "why" part slimmer.
Comments?
Sam
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 2180c88..4e5f0aa 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -113,30 +113,33 @@ # See Documentation/kbuild/makefiles.txt ifneq ($(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)';) make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))) +# Any prerequisites that require target to be built - phony prereq's skipped +get-prereq = $(filter-out $(PHONY),$?) + # function to only execute the passed command if necessary # >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file # note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars # -if_changed = $(if $(strip $(filter-out $(PHONY),$?) \ - $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ +if_changed = $(if $(strip $(get-prereq) $(arg-check) ), \ @set -e; \ $(echo-cmd) $(cmd_$(1)); \ echo 'cmd_$@ := $(make-cmd)' > $(@D)/.$(@F).cmd) # execute the command and also postprocess generated .d dependencies # file -if_changed_dep = $(if $(strip $(filter-out $(PHONY),$?) \ +if_changed_dep = $(if $(strip $(get-prereq) \ $(filter-out FORCE $(wildcard $^),$^) \ - $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ + $(arg-check) ), \ @set -e; \ $(echo-cmd) $(cmd_$(1)); \ scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(@D)/.$(@F).tmp; \ @@ -146,7 +149,41 @@ if_changed_dep = $(if $(strip $(filter-o # 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; \ +if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?) \ + $(arg-check) ), @set -e; \ $(rule_$(1))) + +### +# why - tell why a a target got build +# enabled by make V=2 +# Output: +# (1) due to: command line change +# (2) due to: file1.h file2.h +# (3) due to: no .cmd file +# (4) due to: target not in $(targets) +# (5) due to: target missing +# (1) The command line stored in the file named dir/.target.cmd +# differed from actual command line. This happens when compiler +# options changes +# (2) Prerequisite is newer than target +# (3) No dir/.target.cmd file (used to store command line) +# (4) 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 +# (5) No target, so we better build it +ifeq ($(KBUILD_VERBOSE),2) +why = \ + $(if $(wildcard $@), \ + $(if $(strip $(get-prereq)),- due to: $(get-prereq), \ + $(if $(arg-check), \ + $(if $(cmd_$@),- due to: command line change, \ + $(if $(filter $@, $(targets)), \ + - due to: no .cmd file, \ + -due to: $(notdir $@) not in $$(targets) \ + ) \ + ) \ + ) \ + ), \ + - due to: target missing \ + ) +echo-why = $(call escsq, $(strip $(why))) +endif - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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