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author | Masahiro Yamada <masahiroy@kernel.org> | 2020-12-01 04:27:48 +0100 |
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committer | Masahiro Yamada <masahiroy@kernel.org> | 2021-02-11 21:11:20 +0100 |
commit | 83272e6d4765df775e43d5fc4797b4b3fe9a97fa (patch) | |
tree | 625f9ca4b46779109a8679b6da679597c6e73d3b /arch/powerpc | |
parent | Makefile: use smaller dictionary size for xz module compression (diff) | |
download | linux-83272e6d4765df775e43d5fc4797b4b3fe9a97fa.tar.xz linux-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 'arch/powerpc')
0 files changed, 0 insertions, 0 deletions