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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Wed, 3 Feb 2021 22:15:59 -0800
Message-ID: <CAKwvOdmb8i=-AxnW5SB8h1KWbP7Ku24z7btaqy+DmRxRyYCsrA@mail.gmail.com>
Subject: Re: [PATCH v7 1/2] Kbuild: make DWARF version a choice
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Jakub Jelinek <jakub@redhat.com>,
        Fangrui Song <maskray@google.com>,
        Caroline Tice <cmtice@google.com>,
        Nick Clifton <nickc@redhat.com>, Yonghong Song <yhs@fb.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Arvind Sankar <nivedita@alum.mit.edu>
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On Wed, Feb 3, 2021 at 4:30 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Feb 4, 2021 at 8:16 AM Nick Desaulniers <ndesaulniers@google.com> wrote:
> >
> > On Wed, Feb 3, 2021 at 2:24 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Sat, Jan 30, 2021 at 10:52 AM Nathan Chancellor <nathan@kernel.org> wrote:
> > > >
> > > > On Fri, Jan 29, 2021 at 04:44:00PM -0800, Nick Desaulniers wrote:
> > > > > Modifies CONFIG_DEBUG_INFO_DWARF4 to be a member of a choice which is
> > > > > the default. Does so in a way that's forward compatible with existing
> > > > > configs, and makes adding future versions more straightforward.
> > > > >
> > > > > GCC since ~4.8 has defaulted to this DWARF version implicitly.
> > > > >
> > > > > Suggested-by: Arvind Sankar <nivedita@alum.mit.edu>
> > > > > Suggested-by: Fangrui Song <maskray@google.com>
> > > > > Suggested-by: Nathan Chancellor <nathan@kernel.org>
> > > > > Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> > > > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> > > >
> > > > One comment below:
> > > >
> > > > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> > > >
> > > > > ---
> > > > >  Makefile          |  5 ++---
> > > > >  lib/Kconfig.debug | 16 +++++++++++-----
> > > > >  2 files changed, 13 insertions(+), 8 deletions(-)
> > > > >
> > > > > diff --git a/Makefile b/Makefile
> > > > > index 95ab9856f357..d2b4980807e0 100644
> > > > > --- a/Makefile
> > > > > +++ b/Makefile
> > > > > @@ -830,9 +830,8 @@ ifneq ($(LLVM_IAS),1)
> > > > >  KBUILD_AFLAGS        += -Wa,-gdwarf-2
> > > >
> > > > It is probably worth a comment somewhere that assembly files will still
> > > > have DWARF v2.
> > >
> > > I agree.
> > > Please noting the reason will be helpful.
> >
> > Via a comment in the source, or in the commit message?
> >
> > >
> > > Could you summarize Jakub's comment in short?
> > > https://patchwork.kernel.org/project/linux-kbuild/patch/20201022012106.1875129-1-ndesaulniers@google.com/#23727667
> >
> > Via a comment in the source, or in the commit message?
>
>
> Both in the source if you can summarize it in three lines or so.
>
>
> If you need to add more detailed explanation,
> please provide it in the commit log.

This information is mostly in the commit log of patch 2.  I will
reword it with additional info from the link you sent, but I find that
such minutiae is resulting in diminishing returns on subsequent
respins of the patch series.  I implore you to reword v8 (which I will
send) as you see fit when applying the series.
-- 
Thanks,
~Nick Desaulniers