From 47801c97deb71b9e279c15a02a44cf00aa11e7d9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 2 Aug 2019 19:23:58 +0900 Subject: kbuild: revive single target %.ko I removed the single target %.ko in commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod") because the modpost stage does not work reliably. For instance, the module dependency, modversion, etc. do not work if we lack symbol information from the other modules. Yet, some people still want to build only one module in their interest, and it may be still useful if it is used within those limitations. Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod") Reported-by: Don Brace Reported-by: Arend Van Spriel Signed-off-by: Masahiro Yamada --- Makefile | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 23cdf1f41364..d1f35e32edc7 100644 --- a/Makefile +++ b/Makefile @@ -1002,6 +1002,8 @@ endif PHONY += prepare0 +export MODORDER := $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)modules.order + ifeq ($(KBUILD_EXTMOD),) core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/ @@ -1771,6 +1773,15 @@ build-dir = $(patsubst %/,%,$(dir $(build-target))) $(Q)$(MAKE) $(build)=$(build-dir) $(build-target) %.symtypes: prepare FORCE $(Q)$(MAKE) $(build)=$(build-dir) $(build-target) +ifeq ($(KBUILD_EXTMOD),) +# For the single build of an in-tree module, use a temporary file to avoid +# the situation of modules_install installing an invalid modules.order. +%.ko: MODORDER := .modules.tmp +endif +%.ko: prepare FORCE + $(Q)$(MAKE) $(build)=$(build-dir) $(build-target:.ko=.mod) + $(Q)echo $(build-target) > $(MODORDER) + $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost # Modules PHONY += / -- cgit v1.2.3-55-g7522 From c07d8d47bca1b325102fa2be3a463075f7b051d9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 8 Aug 2019 20:21:11 +0900 Subject: 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(-) (limited to 'Makefile') 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-)),) -- cgit v1.2.3-55-g7522