On Thu, Jan 14, 2021 at 11:05 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jan 14, 2021 at 1:52 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > Today, I have observed and reported (see [1]) bpf/btf/pahole issues
> > with Clang v12 (from apt.llvm.org) and DWARF-4 ("four").
> > Cannot speak for other compilers and its version.
>
> If these are not specific to DWARF5, then it sounds like
> CONFIG_DEBUG_INFO_DWARF4 should also be marked as `depends on
> !DEBUG_INFO_BTF`? (or !BTF && CC=clang)
>

My experiments yesterday on Wednesday were with GCC v10.2.1 plus LLVM=1.
There were no issues with DWARF v2 and v4 but v5.

Unfortunately, build-time is long here on my systems.

For now, I did CONFIG_DEBUG_INFO_BTF=n.

I have applied attached patch.

Is it possible to re-arrange CC depends?

[ /lib/Kconfig.debug ]

config DEBUG_INFO_DWARF5
       bool "Generate DWARF Version 5 debuginfo"
-       depends on GCC_VERSION >= 50000 || CC_IS_CLANG
-       depends on CC_IS_GCC ||
$(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC)
$(CLANG_FLAGS))
+      depends on CC_IS_GCC && GCC_VERSION >= 50000 || CC_IS_CLANG
+      depends on $(success,$(srctree)/scripts/test_dwarf5_support.sh
$(CC) $(CLANG_FLAGS))
+       depends on !DEBUG_INFO_BTF
       help
         Generate DWARF v5 debug info. Requires binutils 2.35, gcc 5.0+ (gcc
         5.0+ accepts the -gdwarf-5 flag but only had partial support for some

And adding text to help concerning DEBUG_INFO_BTF is no good these days.

BTW, if you do not mind:

Label your patches with "*k*build:" not "*K*build:".

Use "DWARF *v*ersion" not "DWARF *V*ersion" - everywhere.

One patch missed the label "kbuild:" (guess the subject has too many
characters).

From what I remember - but these are small nits.

Thanks for DWARF v5 support in Linux.

- Sedat -

> >
> > - Sedat -
> >
> > [1] https://lore.kernel.org/bpf/CA+icZUWb3OyaSQAso8LhsRifZnpxAfDtuRwgB786qEJ3GQ+kRw@mail.gmail.com/T/#m6d05cc6c634e9cee89060b2522abc78c3705ea4c
> --
> Thanks,
> ~Nick Desaulniers