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

[Gregory Rose]

On 2/1/2020 10:07 PM, Masahiro Yamada wrote:
> On Thu, Jan 30, 2020 at 3:09 AM Gregory Rose <gvrose8192@xxxxxxxxx> wrote:
> > On 1/28/2020 7:37 AM, Gregory Rose wrote:
> > > 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
> > Hi Masahiro,
> >
> > I'm unable to get that to work.  KCFLAGS does not seem to be used in
> > Makefile.modfinal.
>
> I quickly tested it, and confirmed
> KCFLAGS works for external modules, too.
>
>
> Makefile.modfinal includes scripts/Makefile.lib
>
>
> So,  c_flags contains $(KCFLAGS)
>
>   c_flags -> KBUILD_CFLAGS -> KCFLAGS

Hi Masahiro,

I must have missed something then - again, my unfamiliarity with the 
Linux Makefiles is probably tripping me up. I'll
dig around and see if I can get that working.

Thanks for your help,

- Greg