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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Fri, 29 Jan 2021 14:05:59 -0800
Message-ID: <CAKwvOdm-+xK=diSKKXXnS2m1+W6QZ70c7cRKTbtVF=dWi1_8_w@mail.gmail.com>
Subject: Re: [PATCH v6 2/2] Kbuild: implement support for DWARF v5
To:     Jakub Jelinek <jakub@redhat.com>, Nick Clifton <nickc@redhat.com>
Cc:     Sedat Dilek <sedat.dilek@gmail.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Clang-Built-Linux ML <clang-built-linux@googlegroups.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Fangrui Song <maskray@google.com>,
        Caroline Tice <cmtice@google.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 Fri, Jan 29, 2021 at 1:11 PM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Fri, Jan 29, 2021 at 01:05:56PM -0800, Nick Desaulniers wrote:
> > > Wasn't that fixed in GAS?
> > > https://sourceware.org/bugzilla/show_bug.cgi?id=27195
> >
> > $ make LLVM=1 -j72 defconfig
> > $ ./scripts/config -e DEBUG_INFO -e DEBUG_INFO_DWARF5
> > $ make LLVM=1 -j72
> > ...
> > /tmp/init-d50d89.s: Assembler messages:
> > /tmp/init-d50d89.s:10: Error: file number less than one
> > /tmp/init-d50d89.s:11: Error: junk at end of line, first unrecognized
> > character is `m'
> >
> > which is https://sourceware.org/bugzilla/show_bug.cgi?id=25611.
> >
> > $ as --version | head -n1
> > GNU assembler (GNU Binutils for Debian) 2.35.1
> >
> > Maybe GAS should not need to be told -gdwarf-5 to parse these?  Then
> > we would not need to pass -Wa,-gdwarf-5 via clang with
> > -no-integrated-as.
>
> That is what sw#27195 is about, just try current binutils 2.35, 2.36 or
> trunk branches.

Ah, I see.  Then I should update the script I add
(scripts/test_dwarf5_support.sh) to feature detect that bug, since
it's the latest of the bunch.  Also, should update my comment to note
that this requires binutils greater than 2.35.1 (which is what I have,
which fails, since the backport landed in ... what?!)  How was this
backported to 2.35
(https://sourceware.org/bugzilla/show_bug.cgi?id=27195#c12, Jan 26
2021) when binutils-2_35_1 was tagged sept 19 2020?  Or will there be
a binutils 2.35.2 point release?
-- 
Thanks,
~Nick Desaulniers