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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 3 Nov 2020 16:05:36 -0800
Message-ID: <CAKwvOdnFstgMa3c+=Vo=QtFYsABDekVeddcPmP=8Pn2bqWfxpg@mail.gmail.com>
Subject: Re: [PATCH] Kbuild: implement support for DWARF5
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        linux-toolchains@vger.kernel.org
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On Tue, Nov 3, 2020 at 4:00 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> On Wed, Oct 21, 2020 at 06:21:06PM -0700, Nick Desaulniers wrote:
> > Further -gdwarf-X where X is an unsupported value doesn't
> > produce an error in $(CC).
>
> Do you have more details here? On godbolt.org, gcc does report an error
> for unsupported dwarf versions.
>
> https://godbolt.org/z/G35798
>
> gcc does not seem to pass the -gdwarf-* options to the assembler when
> compiling C source. For assembler, gcc will pass an appropriate option
> depending on the version of binutils it was configured with: if the
> assembler doesn't support dwarf-5 it can call it with --gdwarf2 for eg.
>
> If the user is using a properly configured toolchain it doesn't look
> like it should be an issue to just use cc-option?

I wrote the base patch back in May, and didn't revisit until recently.
I could have sworn the cc-option silently failed for the check
cc-option does, which is /dev/null input.  I need to recheck that, but
it doesn't hurt to simply include it for now, which I've done in a v2
I'm about to send.
-- 
Thanks,
~Nick Desaulniers