From b999923c29d69d795229e5bf1b49e1266491ff35 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 22 Feb 2019 16:40:08 +0900 Subject: [PATCH] kbuild: remove empty rules for makefiles The previous commit made 'MAKEFLAGS += -rR' effective in the top Makefile regardless of O= option, GNU Make versions. The top Makefile does not need to cancel implicit rules for makefiles. There is still one place where an empty rule is useful. Since -rR is effective only after sub-make, GNU Make would try implicit rules to update the top Makefile. Although it is not a big overhead, cancel it just in case. Signed-off-by: Masahiro Yamada --- Makefile | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/Makefile b/Makefile index db3cb73d3088..418d205581d5 100644 --- a/Makefile +++ b/Makefile @@ -37,6 +37,10 @@ ifneq ($(sub-make-done),1) # (this increases performance and avoids hard-to-debug behaviour) MAKEFLAGS += -rR +# 'MAKEFLAGS += -rR' does not become immediately effective for old +# GNU Make versions. Cancel implicit rules for this Makefile. +$(lastword $(MAKEFILE_LIST)): ; + # Avoid funny character set dependencies unexport LC_ALL LC_COLLATE=C @@ -120,9 +124,6 @@ ifeq ("$(origin O)", "command line") KBUILD_OUTPUT := $(O) endif -# Cancel implicit rules on top Makefile -$(CURDIR)/Makefile Makefile: ; - ifneq ($(words $(subst :, ,$(CURDIR))), 1) $(error main directory cannot contain spaces nor colons) endif @@ -303,8 +304,6 @@ __build_one_by_one: else -# We need some generic definitions (do not try to remake the file). -scripts/Kbuild.include: ; include scripts/Kbuild.include # Read KERNELRELEASE from include/config/kernel.release (if it exists) @@ -1760,9 +1759,7 @@ cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \ # read saved command lines for existing targets existing-targets := $(wildcard $(sort $(targets))) -cmd_files := $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) -$(cmd_files): ; # Do not try to update included dependency files --include $(cmd_files) +-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) endif # ifeq ($(config-targets),1) endif # ifeq ($(mixed-targets),1)