On Mon 12 Dec 2022 10:21:10 GMT, Nathan Chancellor wrote:
> On Sun, Dec 11, 2022 at 12:03:52PM +0900, Masahiro Yamada wrote:
> > Documentation/process/changes.rst notes the minimal GNU Make version,
> > but it is not checked anywhere.
> > 
> > We could check $(MAKE_VERSION), but another simple way is to check
> > $(.FEATURES) since the feature list always grows although this way
> > is not always possible. For example Make 4.0 through 4.2 have the
> > same set of $(.FEATURES).
> > 
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> 
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

> > ---
> > 
> > Changes in v3:
> >   - Check the version in a different way
> > 
> >  Makefile | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/Makefile b/Makefile
> > index 2dda1e9a717a..66dfc5751470 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -11,6 +11,11 @@ NAME = Hurr durr I'ma ninja sloth
> >  # Comments in this file are targeted only to the developer, do not
> >  # expect to learn how to build the kernel reading this file.
> >  
> > +# Ensure Make >= 3.82
> > +ifeq ($(filter undefine,$(.FEATURES)),)
> > +$(error Make $(MAKE_VERSION) is too old)
> 
> Would it make sense to state what version is needed, similar to the
> Kconfig checks for compiler and binutils?

Checking against 'undefine' (introduced in make-3.82~38) is quite a 
nice way, I think.  Otherwise we needed something like
$(filter 3.82% 3.9% 4.% 5.% ..., $(MAKE_VERSION)).

Kind regards,
Nicolas