| Message ID | 1462603706-6324-1-git-send-email-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, May 07, 2016 at 03:48:26PM +0900, Masahiro Yamada wrote: > Currently, arg-check is implemented as follows: > > arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ > $(filter-out $(cmd_$@), $(cmd_$(1))) ) > > This does not care about the order of arguments that appear in > $(cmd_$(1)) and $(cmd_$@). So, if_changed and friends never rebuild > the target if only the argument order is changed. This is a problem > when the link order is changed. > > Apparently, > > obj-y += foo.o > obj-y += bar.o > > and > > obj-y += bar.o > obj-y += foo.o > > should be distinguished because the link order determines the probe > order of drivers. So, built-in.o should be rebuilt when the order > of objects is changed. > > This commit fixes arg-check to compare the old/current commands > including the argument order. > > Of course, this change has a side effect; Kbuild will react to the > change of compile option order. For example, "-DFOO -DBAR" and > "-DBAR -DFOO" should give no difference to the build result, but > false positive should be better than false negative. Agreed. Applied to kbuild.git#kbuild now. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index b2ab2a9..c4467e2 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -7,6 +7,7 @@ quote := " squote := ' empty := space := $(empty) $(empty) +space_escape := _-_SPACE_-_ ### # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o @@ -226,10 +227,10 @@ objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o))) # See Documentation/kbuild/makefiles.txt for more info ifneq ($(KBUILD_NOCMDDEP),1) -# Check if both arguments has same arguments. Result is empty string if equal. -# User may override this check using make KBUILD_NOCMDDEP=1 -arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ - $(filter-out $(cmd_$@), $(cmd_$(1))) ) +# Check if both arguments are the same including their order. Result is empty +# string if equal. User may override this check using make KBUILD_NOCMDDEP=1 +arg-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \ + $(subst $(space),$(space_escape),$(strip $(cmd_$1)))) else arg-check = $(if $(strip $(cmd_$@)),,1) endif @@ -341,8 +342,6 @@ endif # ############################################################################### # -space_escape := %%%SPACE%%% -# define config_filename ifneq ($$(CONFIG_$(1)),"") $(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
Currently, arg-check is implemented as follows: arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ $(filter-out $(cmd_$@), $(cmd_$(1))) ) This does not care about the order of arguments that appear in $(cmd_$(1)) and $(cmd_$@). So, if_changed and friends never rebuild the target if only the argument order is changed. This is a problem when the link order is changed. Apparently, obj-y += foo.o obj-y += bar.o and obj-y += bar.o obj-y += foo.o should be distinguished because the link order determines the probe order of drivers. So, built-in.o should be rebuilt when the order of objects is changed. This commit fixes arg-check to compare the old/current commands including the argument order. Of course, this change has a side effect; Kbuild will react to the change of compile option order. For example, "-DFOO -DBAR" and "-DBAR -DFOO" should give no difference to the build result, but false positive should be better than false negative. I am moving space_escape to the top of Kbuild.include just for a matter of preference. In practical terms, space_escape can be defined after arg-check because arg-check uses "=" flavor, not ":=". Having said that, collecting convenient variables in one place makes sense from the point of readability. Chaining "%%%SPACE%%%" to "_-_SPACE_-_" is also a matter of taste at this point. Actually, it can be arbitrary as long as it is an unlikely used string. The only problem I see in "%%%SPACE%%%" is that "%" is a special character in "$(patsubst ...)" context. This commit just uses "$(subst ...)" for arg-check, but I am fixing it now in case we might want to use it in $(patsubst ...) context in the future. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Changes in v2: - V1 did not work. Change the approach. scripts/Kbuild.include | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)