Re: [PATCH 1/3] kbuild: raise the minimum GNU Make requirement to 4.0

[Nathan Chancellor <nathan@kernel.org>]

On Thu, Jul 04, 2024 at 10:47:55PM +0900, Masahiro Yamada wrote:
> 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.

Seems reasonable. If someone gets bit by this, I think they can just
build make from scratch if they really need to keep building on this
distribution.

> 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>

> ---
> 
>  Documentation/process/changes.rst |  4 ++--
>  Makefile                          | 22 +++-------------------
>  scripts/Kbuild.include            |  2 +-
>  3 files changed, 6 insertions(+), 22 deletions(-)
> 
> diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
> index 5685d7bfe4d0..415ac8eeb46c 100644
> --- a/Documentation/process/changes.rst
> +++ b/Documentation/process/changes.rst
> @@ -33,7 +33,7 @@ GNU C                  5.1              gcc --version
>  Clang/LLVM (optional)  13.0.1           clang --version
>  Rust (optional)        1.78.0           rustc --version
>  bindgen (optional)     0.65.1           bindgen --version
> -GNU make               3.82             make --version
> +GNU make               4.0              make --version
>  bash                   4.2              bash --version
>  binutils               2.25             ld -v
>  flex                   2.5.35           flex --version
> @@ -111,7 +111,7 @@ It depends on ``libclang``.
>  Make
>  ----
>  
> -You will need GNU make 3.82 or later to build the kernel.
> +You will need GNU make 4.0 or later to build the kernel.
>  
>  Bash
>  ----
> diff --git a/Makefile b/Makefile
> index 06aa6402b385..c90d408c825e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -11,8 +11,8 @@ NAME = Baby Opossum Posse
>  # 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 __%, $(MAKECMDGOALS)), \
> @@ -93,15 +93,7 @@ endif
>  
>  # If the user is running make -s (silent mode), suppress echoing of
>  # commands
> -# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
> -
> -ifeq ($(filter 3.%,$(MAKE_VERSION)),)
> -short-opts := $(firstword -$(MAKEFLAGS))
> -else
> -short-opts := $(filter-out --%,$(MAKEFLAGS))
> -endif
> -
> -ifneq ($(findstring s,$(short-opts)),)
> +ifneq ($(findstring s,$(firstword -$(MAKEFLAGS))),)
>  quiet=silent_
>  override KBUILD_VERBOSE :=
>  endif
> @@ -201,14 +193,6 @@ ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
>  $(error source directory cannot contain spaces or colons)
>  endif
>  
> -ifneq ($(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
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index faf37bafa3f8..ed8a7493524b 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -68,7 +68,7 @@ kbuild-file = $(or $(wildcard $(src)/Kbuild),$(src)/Makefile)
>  # Read a file, replacing newlines with spaces
>  #
>  # Make 4.2 or later can read a file by using its builtin function.
> -ifneq ($(filter-out 3.% 4.0 4.1, $(MAKE_VERSION)),)
> +ifneq ($(filter-out 4.0 4.1, $(MAKE_VERSION)),)
>  read-file = $(subst $(newline),$(space),$(file < $1))
>  else
>  read-file = $(shell cat $1 2>/dev/null)
> -- 
> 2.43.0
>