From: Nick Desaulniers <ndesaulniers@google.com>
To: Fangrui Song <maskray@google.com>
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
Subject: Re: [PATCH] Kbuild: implement support for DWARF5
Date: Tue, 3 Nov 2020 14:27:05 -0800 [thread overview]
Message-ID: <CAKwvOdmLN5BWAh35z2LyHvQ_P4pgyCaFohOphpgXUmMAehnV_g@mail.gmail.com> (raw)
In-Reply-To: <20201022014448.mcx5n7unf7kkka3o@google.com>
On Wed, Oct 21, 2020 at 6:44 PM Fangrui Song <maskray@google.com> wrote:
>
> On 2020-10-21, 'Nick Desaulniers' via Clang Built Linux wrote:
> >DWARF5 is the latest standard of the DWARF debug info format.
> >
> >Feature detection of DWARF5 is onerous, especially given that we've
> >removed $(AS), so we must query $(CC) for DWARF5 assembler directive
> >support. Further -gdwarf-X where X is an unsupported value doesn't
> >produce an error in $(CC). GNU `as` only recently gained support for
> >specifying -gdwarf-5.
> >
> >The DWARF version of a binary can be validated with:
>
> To be more correct: this is just the version number of the .debug_info section.
> Other sections can use different version numbers.
> (For example, GNU as still does not support version 5 .debug_line)
How do you recommend we validate that then?
>
> >$ llvm-dwarfdump vmlinux | head -n 5 | grep version
> >or
> >$ readelf --debug-dump=info vmlinux 2>/dev/null | grep Version
> >diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> >index cd14444bf600..0382808ef9fe 100644
> >--- a/include/asm-generic/vmlinux.lds.h
> >+++ b/include/asm-generic/vmlinux.lds.h
> >@@ -828,7 +828,11 @@
> > .debug_types 0 : { *(.debug_types) } \
> > /* DWARF 5 */ \
> > .debug_macro 0 : { *(.debug_macro) } \
> >- .debug_addr 0 : { *(.debug_addr) }
> >+ .debug_addr 0 : { *(.debug_addr) } \
> >+ .debug_line_str 0 : { *(.debug_line_str) } \
> >+ .debug_loclists 0 : { *(.debug_loclists) } \
> >+ .debug_rnglists 0 : { *(.debug_rnglists) } \
> >+ .debug_str_offsets 0 : { *(.debug_str_offsets) }
>
> Consider adding .debug_names for the accelerator table.
> It is the DWARF v5 version of .debug_pub{names,types} (which are mentioned
> a few lines above).
I hadn't seen that section produced in my limited testing. Being a
fan of TDD, I kind of would like to see the linker warn on orphan
section placement, then add it to the list, as I did with the above.
Do you have more info on when or how .debug_pub* can be produced?
Thanks for the rest of the feedback, I'll incorporate it into v2.
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2020-11-03 22:27 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 1:21 [PATCH] Kbuild: implement support for DWARF5 Nick Desaulniers
2020-10-22 1:44 ` Fangrui Song
2020-11-03 22:27 ` Nick Desaulniers [this message]
2020-10-28 18:18 ` Nick Desaulniers
2020-11-02 2:20 ` Masahiro Yamada
2020-11-02 8:18 ` Jakub Jelinek
2020-11-03 22:21 ` Nick Desaulniers
2020-11-04 12:19 ` Jakub Jelinek
2020-11-03 22:13 ` Nick Desaulniers
2020-11-04 0:53 ` [PATCH v2 0/4] Kbuild: DWARF v5 support Nick Desaulniers
2020-11-04 0:53 ` [PATCH v2 1/4] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S Nick Desaulniers
2020-11-04 0:53 ` [PATCH v2 2/4] Kbuild: do not emit debug info for assembly with LLVM_IAS=1 Nick Desaulniers
2020-11-05 6:58 ` Nathan Chancellor
2020-11-05 7:26 ` Fangrui Song
2020-11-09 18:28 ` Nick Desaulniers
2020-11-09 18:35 ` [PATCH v3] " Nick Desaulniers
2020-11-16 23:41 ` Nick Desaulniers
[not found] ` <CA+SOCLJTg6U+Ddop_5O-baVR42va3vGAvMQ62o9H6rd+10aKrw@mail.gmail.com>
2020-11-23 18:42 ` Nick Desaulniers
2020-11-24 18:44 ` Masahiro Yamada
2020-11-04 0:53 ` [PATCH v2 3/4] Kbuild: make DWARF version a choice Nick Desaulniers
2020-11-05 5:58 ` kernel test robot
2020-11-23 23:22 ` Arvind Sankar
2020-11-24 0:33 ` Segher Boessenkool
2020-11-24 16:56 ` Arvind Sankar
2020-11-24 17:46 ` Segher Boessenkool
2020-11-30 18:04 ` Masahiro Yamada
2020-11-30 20:27 ` Fāng-ruì Sòng
2020-12-01 3:38 ` Masahiro Yamada
2020-12-01 9:32 ` Segher Boessenkool
2020-12-02 1:08 ` Fāng-ruì Sòng
2020-11-30 20:45 ` Nick Desaulniers
2020-12-01 4:17 ` Masahiro Yamada
2020-11-04 0:53 ` [PATCH v2 4/4] Kbuild: implement support for DWARF v5 Nick Desaulniers
2020-11-24 17:28 ` Arvind Sankar
2020-12-03 23:22 ` Nick Desaulniers
2020-12-03 23:28 ` Nick Desaulniers
2020-12-04 17:06 ` Arvind Sankar
2020-12-10 23:18 ` Nick Desaulniers
2020-12-11 0:29 ` Arvind Sankar
2020-12-01 1:56 ` Masahiro Yamada
2020-11-04 0:00 ` [PATCH] Kbuild: implement support for DWARF5 Arvind Sankar
2020-11-04 0:05 ` Nick Desaulniers
2020-11-04 0:17 ` Arvind Sankar
2020-12-03 22:56 ` Nick Desaulniers
2020-12-04 0:17 ` Nick Desaulniers
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