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authorMasahiro Yamada <yamada.masahiro@socionext.com>2019-02-22 16:40:08 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2019-02-27 21:43:31 +0900
commitb999923c29d69d795229e5bf1b49e1266491ff35 (patch)
tree64232cc5d117a97eb29e0519e64a11e70fc4a25b
parent3812b8c5c5d527239ac015f1f2c7654da7fcfbba (diff)
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 <yamada.masahiro@socionext.com>
-rw-r--r--Makefile13
1 files 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)