From 87d599fc3955e59b1ed30f350321a4be5353f945 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 13 Dec 2022 20:24:20 +0900 Subject: kbuild: ensure Make >= 3.82 is used 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. GNU Make 3.81 expands $(.FEATURES) to: target-specific order-only second-expansion else-if archives jobserver check-symlink GNU Make 3.82 expands $(.FEATURES) to: target-specific order-only second-expansion else-if shortest-stem undefine archives jobserver check-symlink To ensure Make >= 3.82, you can check either 'shortest-stem' or 'undefine'. This way is not always possible. For example, Make 4.0 through 4.2 have the same set of $(.FEATURES). At that point, we will need to come up with a different approach. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Reviewed-by: Nicolas Schier --- Makefile | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index f506879e7452..5f015f206e12 100644 --- a/Makefile +++ b/Makefile @@ -11,6 +11,10 @@ NAME = Hurr durr I'ma ninja sloth # Comments in this file are targeted only to the developer, do not # expect to learn how to build the kernel reading this file. +ifeq ($(filter undefine,$(.FEATURES)),) +$(error GNU Make >= 3.82 is required. Your Make version is $(MAKE_VERSION)) +endif + $(if $(filter __%, $(MAKECMDGOALS)), \ $(error targets prefixed with '__' are only for internal use)) -- cgit v1.2.3