Re: cifs: Fix tracing build error with O=

[Masahiro Yamada]

On Thu, Jun 20, 2019 at 4:58 PM Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Jun 20, 2019 at 06:54:42AM +0000, yamada.masahiro@xxxxxxxxxxxxx wrote:
> >
> > I cannot reproduce the build error on the latest Linus tree.
> >
> >
> > $ make O=build allmodconfig fs/cifs/
> >
> > perfectly works for me.
>
> I was trying to build just the fs/cifs directory with
>
>         make O=build M=fs/cifs
>
> But I see now that this can't possibly work as M= only supports
> absolute paths.  As M= is supposed to replace SUBDIRS=, what are
> we supposed to do to build just a directory?


Documentation/kbuild/kbuild.txt says
M= and KBUILD_EXTMOD (and older form SUBDIRS= too)
are for building external modules.

Yet, many people still wrongly use them to build
in-kernel directories just because they seem to work
(but do not really).

The similar question, and the answer is here:
https://lkml.org/lkml/2019/1/17/584


-- 
Best Regards
Masahiro Yamada