On Fri, Sep 20, 2024 at 7:39 PM Nicolas Schier <n.schier@xxxxxx> wrote:
>
> On Tue, Sep 17, 2024 at 11:16:28PM +0900, Masahiro Yamada wrote:
> >
> > There has been a long-standing request to support building external
> > modules in a separate build directory.
>
> Thanks a lot, you are making several of my colleages very happy with
> your patch set!
>
> > The first half is cleanups of documents and Makefiles.
> >
> > The last part adds KBUILD_EXTMOD_OUTPUT (MO=).
> > This is too big changes, and too late for the current MW.
> > (I did not test kselftest at all.)
> > I hope people test this and may uncover some issues.
>
> I'm not through all the patches in detail yet, just one observation beforehand:
>
> $ make KBUILD_OUTPUT=build allnoconfig
> $ ./scripts/config --file build/.config --enable modules --enable accessibility
> $ make KBUILD_OUTPUT=build olddefconfig
> $ make KBUILD_OUTPUT=build
> $ make KBUILD_OUTPUT=build CONFIG_SPEAKUP=m MO=/tmp/build M=~+/drivers/accessibility/speakup modules
> /home/nschier/src/kbuild-review/drivers/accessibility/speakup/genmap.c:23:10: fatal error: mapdata.h: No such file or directory
> 23 | #include "mapdata.h"
> | ^~~~~~~~~~~
> compilation terminated.
> make[3]: *** [/home/nschier/src/kbuild-review/scripts/Makefile.host:133: genmap.o] Error 1
> make[3]: *** Waiting for unfinished jobs....
> make[2]: *** [/home/nschier/src/kbuild-review/Makefile:1971: .] Error 2
> make[1]: *** [/home/nschier/src/kbuild-review/Makefile:251: __sub-make] Error 2
> make: *** [Makefile:251: __sub-make] Error 2
> [exit code 2]
>
> If I add "EXTRA_CFLAGS=-I${MO} and EXTRA_HOSTCFLAGS=-I${MO}" to the module
> build command, it works as expected.
>
> Patching this into kbuild works for me, too, but I haven't checked whether it
> breaks some other scenarios:
>
> diff --git a/scripts/Makefile.host b/scripts/Makefile.host
> index e01c13a588dd..056c7da2776f 100644
> --- a/scripts/Makefile.host
> +++ b/scripts/Makefile.host
> @@ -97,10 +97,13 @@ hostrust_flags = --out-dir $(dir $@) --emit=dep-info=$(depfile) \
> $(HOSTRUSTFLAGS_$(target-stem))
>
> # $(objtree)/$(obj) for including generated headers from checkin source files
> -ifeq ($(KBUILD_EXTMOD),)
> ifdef building_out_of_srctree
> +ifeq ($(KBUILD_EXTMOD),)
> hostc_flags += -I $(objtree)/$(obj)
> hostcxx_flags += -I $(objtree)/$(obj)
> +else
> +hostc_flags += -I $(CURDIR)
> +hostcxx_flags += -I $(CURDIR)
> endif
> endif
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 1bdd77f42289..428a9eb74381 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -190,11 +190,15 @@ endif
>
> # $(src) for including checkin headers from generated source files
> # $(obj) for including generated headers from checkin source files
> -ifeq ($(KBUILD_EXTMOD),)
> ifdef building_out_of_srctree
> +ifeq ($(KBUILD_EXTMOD),)
> _c_flags += $(addprefix -I, $(src) $(obj))
> _a_flags += $(addprefix -I, $(src) $(obj))
> _cpp_flags += $(addprefix -I, $(src) $(obj))
> +else
> +_c_flags += $(addprefix -I, $(src) $(obj) $(CURDIR))
> +_a_flags += $(addprefix -I, $(src) $(obj) $(CURDIR))
> +_cpp_flags += $(addprefix -I, $(src) $(obj) $(CURDIR))
> endif
> endif
>
> Is '-I$(MO)' in CFLAGS/HOSTCFLAGS is something we should support by
> default, or should this be added to the external module's Makefile by
> the respective developers themselves?
>
> Kind regards,
> Nicolas
We can fix it more simply.
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index e01c13a588dd..c1dedf646a39 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -96,12 +96,10 @@ hostrust_flags = --out-dir $(dir $@)
--emit=dep-info=$(depfile) \
$(KBUILD_HOSTRUSTFLAGS) $(HOST_EXTRARUSTFLAGS) \
$(HOSTRUSTFLAGS_$(target-stem))
-# $(objtree)/$(obj) for including generated headers from checkin source files
-ifeq ($(KBUILD_EXTMOD),)
+# $(obj) for including generated headers from checkin source files
ifdef building_out_of_srctree
-hostc_flags += -I $(objtree)/$(obj)
-hostcxx_flags += -I $(objtree)/$(obj)
-endif
+hostc_flags += -I $(obj)
+hostcxx_flags += -I $(obj)
endif
#####
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 1bdd77f42289..d8ce0f59fd17 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -190,13 +190,11 @@ endif
# $(src) for including checkin headers from generated source files
# $(obj) for including generated headers from checkin source files
-ifeq ($(KBUILD_EXTMOD),)
ifdef building_out_of_srctree
_c_flags += $(addprefix -I, $(src) $(obj))
_a_flags += $(addprefix -I, $(src) $(obj))
_cpp_flags += $(addprefix -I, $(src) $(obj))
endif
-endif
# If $(is-kernel-object) is 'y', this object will be linked to
vmlinux or modules
is-kernel-object = $(or $(part-of-builtin),$(part-of-module))
However, I'd rather fix each Makefile
to add necessary include paths explicitly.
--
Best Regards
Masahiro Yamada
