Dmitrii, Fangrui, and Mashahiro note:

  Before GCC 11 and Clang 12 -gsplit-dwarf implicitly uses -g2.

Fix CONFIG_DEBUG_INFO_SPLIT for gcc-11+ & clang-12+ which now need -g
specified in order for -gsplit-dwarf to work at all.

-gsplit-dwarf has been mutually exclusive with -g since support for
CONFIG_DEBUG_INFO_SPLIT was introduced in
commit 866ced950bcd ("kbuild: Support split debug info v4")
I don't think it ever needed to be.

Link: https://lore.kernel.org/lkml/20220815013317.26121-1-dmitrii.bundin.a@gmail.com/
Link: https://lore.kernel.org/lkml/CAK7LNARPAmsJD5XKAw7m_X2g7Fi-CAAsWDQiP7+ANBjkg7R7ng@mail.gmail.com/
Link: https://reviews.llvm.org/D80391
Cc: Andi Kleen <ak@linux.intel.com>
Reported-by: Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
Reported-by: Fangrui Song <maskray@google.com>
Reported-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Changes v3 -> v4:
* Split into its own patch; we don't have any out of line assembler
  files using .debug_* or .cfi_* directives that would produce
  meaningful debug info in .dwo files.

 scripts/Makefile.debug | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug
index 9f39b0130551..26d6a9d97a20 100644
--- a/scripts/Makefile.debug
+++ b/scripts/Makefile.debug
@@ -1,9 +1,7 @@
-DEBUG_CFLAGS	:=
+DEBUG_CFLAGS	:= -g
 
 ifdef CONFIG_DEBUG_INFO_SPLIT
 DEBUG_CFLAGS	+= -gsplit-dwarf
-else
-DEBUG_CFLAGS	+= -g
 endif
 
 ifndef CONFIG_AS_IS_LLVM
-- 
2.37.3.968.ga6b4b080e4-goog

On Tue, Sep 20, 2022 at 2:30 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> Dmitrii, Fangrui, and Mashahiro note:
>
>   Before GCC 11 and Clang 12 -gsplit-dwarf implicitly uses -g2.
>
> Fix CONFIG_DEBUG_INFO_SPLIT for gcc-11+ & clang-12+ which now need -g
> specified in order for -gsplit-dwarf to work at all.
>
> -gsplit-dwarf has been mutually exclusive with -g since support for
> CONFIG_DEBUG_INFO_SPLIT was introduced in
> commit 866ced950bcd ("kbuild: Support split debug info v4")
> I don't think it ever needed to be.
>
> Link: https://lore.kernel.org/lkml/20220815013317.26121-1-dmitrii.bundin.a@gmail.com/
> Link: https://lore.kernel.org/lkml/CAK7LNARPAmsJD5XKAw7m_X2g7Fi-CAAsWDQiP7+ANBjkg7R7ng@mail.gmail.com/
> Link: https://reviews.llvm.org/D80391
> Cc: Andi Kleen <ak@linux.intel.com>
> Reported-by: Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
> Reported-by: Fangrui Song <maskray@google.com>
> Reported-by: Masahiro Yamada <masahiroy@kernel.org>
> Suggested-by: Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---


Applied to linux-kbuild/fixes.
Thanks.



> Changes v3 -> v4:
> * Split into its own patch; we don't have any out of line assembler
>   files using .debug_* or .cfi_* directives that would produce
>   meaningful debug info in .dwo files.
>
>  scripts/Makefile.debug | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug
> index 9f39b0130551..26d6a9d97a20 100644
> --- a/scripts/Makefile.debug
> +++ b/scripts/Makefile.debug
> @@ -1,9 +1,7 @@
> -DEBUG_CFLAGS   :=
> +DEBUG_CFLAGS   := -g
>
>  ifdef CONFIG_DEBUG_INFO_SPLIT
>  DEBUG_CFLAGS   += -gsplit-dwarf
> -else
> -DEBUG_CFLAGS   += -g
>  endif
>
>  ifndef CONFIG_AS_IS_LLVM
> --
> 2.37.3.968.ga6b4b080e4-goog
>


-- 
Best Regards
Masahiro Yamada