kbuild: raise the minimum GNU Make requirement to 4.0
RHEL/CentOS 7, popular distributions that install GNU Make 3.82, reached
EOM/EOL on June 30, 2024. While you may get extended support, it is a
good time to raise the minimum GNU Make version.
The new requirement, GNU Make 4.0, was released in October, 2013.
I did not touch the Makefiles under tools/ because I do not know the
requirements for building tools. I do not find any GNU Make version
checks under tools/.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
diff --git a/Makefile b/Makefile
index b25b5b4..7372ea4 100644
--- a/Makefile
+++ b/Makefile
@@ -11,8 +11,8 @@
# Comments in this file are targeted only to the developer, do not
# expect to learn how to build the kernel reading this file.
-ifeq ($(filter undefine,$(.FEATURES)),)
-$(error GNU Make >= 3.82 is required. Your Make version is $(MAKE_VERSION))
+ifeq ($(filter output-sync,$(.FEATURES)),)
+$(error GNU Make >= 4.0 is required. Your Make version is $(MAKE_VERSION))
endif
$(if $(filter __%, $(MAKECMDGOALS)), \
@@ -93,15 +93,7 @@
# If the user is running make -s (silent mode), suppress echoing of
# commands
-# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
-
-ifeq ($(filter 3.%,$(MAKE_VERSION)),)
-short-opts := $(firstword -$(MAKEFLAGS))
-else
-short-opts := $(filter-out --%,$(MAKEFLAGS))
-endif
-
-ifneq ($(findstring s,$(short-opts)),)
+ifneq ($(findstring s,$(firstword -$(MAKEFLAGS))),)
quiet=silent_
override KBUILD_VERBOSE :=
endif
@@ -201,14 +193,6 @@
$(error source directory cannot contain spaces or colons)
endif
-ifneq ($(filter 3.%,$(MAKE_VERSION)),)
-# 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
-# We need to invoke sub-make to avoid implicit rules in the top Makefile.
-need-sub-make := 1
-# Cancel implicit rules for this Makefile.
-$(this-makefile): ;
-endif
-
export sub_make_done := 1
endif # sub_make_done
