From: Masahiro Yamada <masahiroy@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jakub Jelinek <jakub@redhat.com>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-toolchains@vger.kernel.org,
clang-built-linux <clang-built-linux@googlegroups.com>,
Fangrui Song <maskray@google.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Dmitry Golovin <dima@golovin.in>,
Alistair Delva <adelva@google.com>
Subject: Re: [PATCH v2 3/4] Kbuild: make DWARF version a choice
Date: Tue, 1 Dec 2020 03:04:50 +0900 [thread overview]
Message-ID: <CAK7LNAT5MQqUddv+QbFu5ToLBK3eUPArHSBR=5AOS3ONtMqKaw@mail.gmail.com> (raw)
In-Reply-To: <20201104005343.4192504-4-ndesaulniers@google.com>
On Wed, Nov 4, 2020 at 9:53 AM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@googlegroups.com> wrote:
>
> Modifies CONFIG_DEBUG_INFO_DWARF4 to be a member of a choice. Adds an
> explicit CONFIG_DEBUG_INFO_DWARF2, which is the default. Does so in a
> way that's forward compatible with existing configs, and makes adding
> future versions more straightforward.
>
> Suggested-by: Fangrui Song <maskray@google.com>
> Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> Makefile | 14 ++++++++------
> lib/Kconfig.debug | 19 +++++++++++++++----
> 2 files changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 75b1a3dcbf30..e23786a4c1c7 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -826,12 +826,14 @@ else
> DEBUG_CFLAGS += -g
> endif
>
> -ifndef LLVM_IAS
> -KBUILD_AFLAGS += -Wa,-gdwarf-2
> -endif
> -
> -ifdef CONFIG_DEBUG_INFO_DWARF4
> -DEBUG_CFLAGS += -gdwarf-4
> +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF2) := 2
> +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
> +DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y)
> +ifneq ($(dwarf-version-y)$(LLVM_IAS),21)
> +# Binutils 2.35+ required for -gdwarf-4+ support.
> +dwarf-aflag := $(call as-option,-Wa$(comma)-gdwarf-$(dwarf-version-y))
> +DEBUG_CFLAGS += $(dwarf-aflag)
This changes the behavior.
For the Dwarf-2 case,
Previously, -gdwarf-2 was passed to $(CC),
so the debug info was generated by gcc.
Now, -Wa,-gdwarf-2 is passed to $(CC).
-gdwarf-2 is handled by GNU as.
So, the source info points to /tmp/<hash>.s
instead of the original .c file.
Handling the Dwarf capability is very complicated.
Are you still working for v3?
> +KBUILD_AFLAGS += $(dwarf-aflag)
> endif
>
> ifdef CONFIG_DEBUG_INFO_REDUCED
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 83a860126897..03c494eefabd 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -256,14 +256,25 @@ config DEBUG_INFO_SPLIT
> to know about the .dwo files and include them.
> Incompatible with older versions of ccache.
>
> +choice
> + prompt "DWARF version"
> + help
> + Which version of DWARF debug info to emit.
> +
> +config DEBUG_INFO_DWARF2
> + bool "Generate DWARF v2 debuginfo"
> + help
> + Generate DWARF v2 debug info.
> +
> config DEBUG_INFO_DWARF4
> bool "Generate dwarf4 debuginfo"
> depends on $(cc-option,-gdwarf-4)
> help
> - Generate dwarf4 debug info. This requires recent versions
> - of gcc and gdb. It makes the debug information larger.
> - But it significantly improves the success of resolving
> - variables in gdb on optimized code.
> + Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+.
> + It makes the debug information larger, but it significantly
> + improves the success of resolving variables in gdb on optimized code.
> +
> +endchoice # "DWARF version"
>
> config DEBUG_INFO_BTF
> bool "Generate BTF typeinfo"
> --
> 2.29.1.341.ge80a0c044ae-goog
>
> --
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--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2020-11-30 18:07 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
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 [this message]
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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