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| author |   Masahiro Yamada <masahiroy@kernel.org> | 2020-12-01 12:27:48 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2021-02-12 05:11:20 +0900 |
| commit | 83272e6d4765df775e43d5fc4797b4b3fe9a97fa (patch) | |
| tree | 625f9ca4b46779109a8679b6da679597c6e73d3b /lib | |
| parent | Makefile: use smaller dictionary size for xz module compression (diff) | |
| download | linux-dev-83272e6d4765df775e43d5fc4797b4b3fe9a97fa.tar.xz linux-dev-83272e6d4765df775e43d5fc4797b4b3fe9a97fa.zip | |
kbuild: Remove $(cc-option,-gdwarf-4) dependency from DEBUG_INFO_DWARF4
The -gdwarf-4 flag is supported by GCC 4.5+, and also by Clang.
You can see it at https://godbolt.org/z/6ed1oW
For gcc 4.5.3 pane, line 37: .value 0x4
For clang 10.0.1 pane, line 117: .short 4
Given Documentation/process/changes.rst stating GCC 4.9 is the minimal
version, this cc-option is unneeded.
Note
----
CONFIG_DEBUG_INFO_DWARF4 controls the DWARF version only for C files.
As you can see in the top Makefile, -gdwarf-4 is only passed to CFLAGS.
ifdef CONFIG_DEBUG_INFO_DWARF4
DEBUG_CFLAGS += -gdwarf-4
endif
This flag is used when compiling *.c files.
On the other hand, the assembler is always given -gdwarf-2.
KBUILD_AFLAGS += -Wa,-gdwarf-2
Hence, the debug info that comes from *.S files is always DWARF v2.
This is simply because GAS supported only -gdwarf-2 for a long time.
Recently, GAS gained the support for --gdwarf-[345] options. [1]
And, also we have Clang integrated assembler. So, the debug info
for *.S files might be improved in the future.
In my understanding, the current code is intentional, not a bug.
[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=31bf18645d98b4d3d7357353be840e320649a67d
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 7937265ef879..9cf4d12b81fb 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -258,7 +258,6 @@ config DEBUG_INFO_SPLIT 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. |