On Fri, Sep 20, 2024 at 09:58:47PM +0900, Masahiro Yamada wrote:
> 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.
Ah, yes.
> 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.
Sure, clearly makes sense. Especially as the explicit include path
addition is also as simple as:
HOSTCFLAGS_genmap.o += -I $(obj)
CFLAGS_main.o += -I $(obj)
Kind regards,
Nicolas
