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SubjectRe: [PATCH v4] Makefile.debug: re-enable debug info for .S files
On Sat, Sep 24, 2022 at 11:20 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Fri, Sep 23, 2022 at 7:12 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > This patch still misses the debug info for *.S files
> > for the combination of LLVM_IAS=0 and
> > CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
> > because, as the comment says, Clang does not pass -g down to GAS.
> >
> >
> > With "[v4] Makefile.debug: set -g unconditional on CONFIG_DEBUG_INFO_SPLIT"
> > and this one applied,
> >
> >
> >
> > $ grep CONFIG_DEBUG_INFO_DWARF .config
> > CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
> > # CONFIG_DEBUG_INFO_DWARF4 is not set
> > # CONFIG_DEBUG_INFO_DWARF5 is not set
> > $ make LLVM=1 LLVM_IAS=0 arch/x86/kernel/irqflags.o
> > SYNC include/config/auto.conf.cmd
> > SYSHDR arch/x86/include/generated/asm/unistd_32_ia32.h
> > SYSHDR arch/x86/include/generated/asm/unistd_64_x32.h
> > SYSTBL arch/x86/include/generated/asm/syscalls_64.h
> > HOSTCC arch/x86/tools/relocs_32.o
> > [snip]
> > AS arch/x86/kernel/irqflags.o
> > $ objdump -h arch/x86/kernel/irqflags.o | grep debug
> > $
> >
> >
> >
> >
> >
> >
> >
> >
> > I think the following fix-up is needed on top.
> >
> >
> >
> >
> > diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug
> > index d6aecd78b942..8cf1cb22dd93 100644
> > --- a/scripts/Makefile.debug
> > +++ b/scripts/Makefile.debug
> > @@ -1,4 +1,5 @@
> > -DEBUG_CFLAGS := -g
> > +DEBUG_CFLAGS :=
> > +debug-flags-y := -g
> >
> > ifdef CONFIG_DEBUG_INFO_SPLIT
> > DEBUG_CFLAGS += -gsplit-dwarf
> >
> >
> >
> >
> > Then, I can see the debug sections.
> >
> >
> >
> > $ make LLVM=1 LLVM_IAS=0 arch/x86/kernel/irqflags.o
> > CALL scripts/checksyscalls.sh
> > DESCEND objtool
> > AS arch/x86/kernel/irqflags.o
> > $ objdump -h arch/x86/kernel/irqflags.o | grep debug
> > 6 .debug_line 00000050 0000000000000000 0000000000000000 0000008f 2**0
> > 7 .debug_info 0000002e 0000000000000000 0000000000000000 000000f8 2**0
> > 8 .debug_abbrev 00000014 0000000000000000 0000000000000000 000001d0 2**0
> > 9 .debug_aranges 00000030 0000000000000000 0000000000000000 000001f0 2**4
> > 10 .debug_str 0000004d 0000000000000000 0000000000000000 00000250 2**0
> >
> >
> >
> >
> >
> > If you agree, I can locally fix it up as such.
>
> Ah, sorry I missed testing that combination. Thanks for your
> thoroughness. Yes please apply that diff on top.
> --
> Thanks,
> ~Nick Desaulniers



Applied to linux-kbuild with the fixup.



--
Best Regards
Masahiro Yamada

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