From c07d8d47bca1b325102fa2be3a463075f7b051d9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 8 Aug 2019 20:21:11 +0900 Subject: [PATCH] kbuild: show hint if subdir-y/m is used to visit module Makefile Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod"), a module is no longer built in the following pattern: [Makefile] subdir-y := some-module [some-module/Makefile] obj-m := some-module.o You cannot write Makefile this way in upstream because modules.order is not correctly generated. subdir-y is used to descend to a sub-directory that builds tools, device trees, etc. For external modules, the modules order does not matter. So, the Makefile above was known to work. I believe the Makefile should be re-written as follows: [Makefile] obj-m := some-module/ [some-module/Makefile] obj-m := some-module.o However, people will have no idea if their Makefile suddenly stops working. In fact, I received questions from multiple people. Show a warning for a while if obj-m is specified in a Makefile visited by subdir-y or subdir-m. I touched the %/ rule to avoid false-positive warnings for the single target. Cc: Jan Kiszka Cc: Tom Stonecypher Signed-off-by: Masahiro Yamada Tested-by: Jan Kiszka --- Makefile | 2 +- scripts/Makefile.build | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index d1f35e32edc7..fd219e1452a0 100644 --- a/Makefile +++ b/Makefile @@ -1788,7 +1788,7 @@ PHONY += / /: ./ %/: prepare FORCE - $(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir) + $(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir) need-modorder=1 # FIXME Should go into a make.lib or something # =========================================================================== diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 37a1d2cd49d4..2f66ed388d1c 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -52,6 +52,13 @@ ifndef obj $(warning kbuild: Makefile.build is included improperly) endif +ifeq ($(MAKECMDGOALS)$(need-modorder),) +ifneq ($(obj-m),) +$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.) +$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.) +endif +endif + # =========================================================================== ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),) -- 2.30.2