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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Wed, 27 Feb 2019 21:32:08 +0900
Message-ID: <CAK7LNATtUnSV-OKnrH+xvmWU1scJCCFr-EH-qJ_5djhgwf8BpA@mail.gmail.com>
Subject: Re: [PATCH 5/5] scripts/gdb: refactor rules for symlink creation
To:     kieran.bingham@ideasonboard.com
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Jan Kiszka <jan.kiszka@siemens.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi Kieran,


On Wed, Feb 27, 2019 at 8:56 PM Kieran Bingham
<kieran.bingham@ideasonboard.com> wrote:
>
> Hi Yamada-san,
>
> On 19/02/2019 09:33, Masahiro Yamada wrote:
> > gdb-scripts is not a real object, but (ab)used like a phony target.
> >
> > Rewrite the code in a more Kbuild-ish way. Add symlinks to extra-y
> > and use if_changed.
> >
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> > ---
> >
> >  scripts/gdb/linux/Makefile | 18 +++++++++++-------
> >  1 file changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/scripts/gdb/linux/Makefile b/scripts/gdb/linux/Makefile
> > index 7545806..3df395a 100644
> > --- a/scripts/gdb/linux/Makefile
> > +++ b/scripts/gdb/linux/Makefile
> > @@ -1,13 +1,17 @@
> >  # SPDX-License-Identifier: GPL-2.0
> > -always := gdb-scripts
> >
> > -SRCTREE := $(abspath $(srctree))
> > -
> > -$(obj)/gdb-scripts:
> >  ifneq ($(KBUILD_SRC),)
> > -     $(Q)ln -fsn $(SRCTREE)/$(obj)/*.py $(objtree)/$(obj)
> > +
> > +symlinks := $(patsubst $(srctree)/$(src)/%,%,$(wildcard $(srctree)/$(src)/*.py))
> > +
> > +quiet_cmd_symlink = SYMLINK $@
> > +      cmd_symlink = ln -fsn $(patsubst $(obj)/%,$(abspath $(srctree))/$(src)/%,$@) $@
> > +
> > +extra-y += $(symlinks)
> > +$(addprefix $(obj)/, $(symlinks)): FORCE
> > +     $(call if_changed,symlink)
> > +
> >  endif
> > -     @:
> >
> >  quiet_cmd_gen_constants_py = GEN     $@
> >        cmd_gen_constants_py = \
> > @@ -18,4 +22,4 @@ extra-y += constants.py
> >  $(obj)/constants.py: $(src)/constants.py.in FORCE
> >       $(call if_changed_dep,gen_constants_py)
> >
> > -clean-files := *.pyc *.pyo $(if $(KBUILD_SRC),*.py)
> > +clean-files := *.pyc *.pyo
>
> Perhaps this answers my earlier question.
> I guess the extra-y hook is somehow handling the clean up of these files?
>
> Aha - yes, I've just found it in
>
> Documentation/kbuild/makefiles.txt:
> > === 5 Kbuild clean infrastructure
> > ...
> > Kbuild knows targets listed in $(hostprogs-y), $(hostprogs-m), $(always), $(extra-y) and $(targets). They are all deleted during "make clean".
>
> Perfect, so this is much better.

Exactly.

If you are interested in the real code,
see scripts/Makefile.clean


__clean-files   := $(extra-y) $(extra-m) $(extra-)       \
                   $(always) $(targets) $(clean-files)   \
                   $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
                   $(hostlibs-y) $(hostlibs-m) $(hostlibs-) \
                   $(hostcxxlibs-y) $(hostcxxlibs-m)


> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
>
> --
> Regards
> --
> Kieran


-- 
Best Regards
Masahiro Yamada