| Message ID | 20190808112111.16159-1-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kbuild: show hint if subdir-y/m is used to visit module Makefile | expand |
On 08.08.19 13:21, Masahiro Yamada wrote: > 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 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 <jan.kiszka@siemens.com> > Cc: Tom Stonecypher <thomas.edwardx.stonecypher@intel.com> > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- > > Changes in v2: > - fix false-positive warnings for single targets > > Makefile | 2 +- > scripts/Makefile.build | 7 +++++++ > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index 0e37ad2f77bf..fac25e279da6 100644 > --- a/Makefile > +++ b/Makefile > @@ -1783,7 +1783,7 @@ 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-)),) > FWIW, I've thrown this patch (with the other 2) at our "special" out-of-tree modules repo, and it worked as expected: Warned when we were still using subdir-y, remained silent after the fix. Tested-by: Jan Kiszka <jan.kiszka@siemens.com> Jan
diff --git a/Makefile b/Makefile index 0e37ad2f77bf..fac25e279da6 100644 --- a/Makefile +++ b/Makefile @@ -1783,7 +1783,7 @@ 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-)),)
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 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 <jan.kiszka@siemens.com> Cc: Tom Stonecypher <thomas.edwardx.stonecypher@intel.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Changes in v2: - fix false-positive warnings for single targets Makefile | 2 +- scripts/Makefile.build | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-)