Re: [PATCH] kbuild: Include external modules compile flags

[Gregory Rose]

On 1/27/2020 7:35 PM, Masahiro Yamada wrote:
> On Tue, Jan 28, 2020 at 6:50 AM Greg Rose <gvrose8192@xxxxxxxxx> wrote:
> > Since this commit:
> > 'commit 9b9a3f20cbe0 ("kbuild: split final module linking out into Makefile.modfinal")'
> > at least one out-of-tree external kernel module build fails
> > during the modfinal make phase because Makefile.modfinal does
> > not include the ccflags-y variable from the exernal module's Kbuild.
> ccflags-y is passed only for compiling C files in that directory.
>
> It is not used for compiling *.mod.c
> This is true for both in-kernel and external modules.
>
> So, ccflags-y is not a good choice
> for passing such flags that should be globally effective.
>
>
> Maybe, KCFLAGS should work.
>
>
> module:
>         $(MAKE) KCFLAGS=...  M=$(PWD) -C /lib/modules/$(uname -r)/build modules

Thanks,

I'll see if I can get that to work.

- Greg


> > Make sure to include the external kernel module's Kbuild so that the
> > necessary command line flags from the external module are set.
> >
> > Reported-by: David Ahern <dsahern@xxxxxxxxx>
> > CC: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> > Signed-off-by: Greg Rose <gvrose8192@xxxxxxxxx>
> > ---
> >   scripts/Makefile.modfinal | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> > index 411c1e60..a645ba6 100644
> > --- a/scripts/Makefile.modfinal
> > +++ b/scripts/Makefile.modfinal
> > @@ -21,6 +21,10 @@ __modfinal: $(modules)
> >   modname = $(notdir $(@:.mod.o=))
> >   part-of-module = y
> >
> > +# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
> > +include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
> > +             $(KBUILD_EXTMOD)/Kbuild)
> > +
> >   quiet_cmd_cc_o_c = CC [M]  $@
> >         cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
> >
> > --
> > 1.8.3.1