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@xxxxxxxxxxxxx>
---
Makefile | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff --git a/Makefile b/Makefile
index 25d7d46..f7f1aa1 100644
--- a/Makefile
+++ b/Makefile
@@ -37,6 +37,10 @@ ifndef KBUILD_SUBMAKE
# (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)
$(error main directory cannot contain spaces nor colons)
endif
@@ -303,8 +304,6 @@ __build_one_by_one:
else
-# We need some generic definitions (do not try to remake the file).
-scripts/Kbuild.include: ;
include scripts/Kbuild.include
# Read KERNELRELEASE from include/config/kernel.release (if it exists)
@@ -627,9 +626,6 @@ ifeq ($(may-sync-config),1)
# because some architectures define CROSS_COMPILE there.
-include include/config/auto.conf.cmd
-# To avoid any implicit rule to kick in, define an empty command
-$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
-
# The actual configuration files used during the build are stored in
# include/generated/ and include/config/. Update them if .config is newer than
# include/config/auto.conf (which mirrors .config).
@@ -1750,9 +1746,7 @@ 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)
--
2.7.4
