Re: [RFC 03/13] objtool: Disassemble code with libopcodes instead of running objdump

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Jun 06, 2025 at 05:34:30PM +0200, Alexandre Chartre wrote:
> objtool executes the objdump command to disassemble code. Use libopcodes
> instead to have more control about the disassembly scope and output.
> 
> Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
> ---
>  tools/objtool/Makefile                  |   2 +-
>  tools/objtool/arch/loongarch/decode.c   |   6 +
>  tools/objtool/arch/powerpc/decode.c     |   6 +
>  tools/objtool/arch/x86/decode.c         |   7 +
>  tools/objtool/check.c                   |   4 +-
>  tools/objtool/disas.c                   | 186 +++++++++++++++---------
>  tools/objtool/include/objtool/arch.h    |   5 +
>  tools/objtool/include/objtool/check.h   |   5 +
>  tools/objtool/include/objtool/objtool.h |   4 +
>  9 files changed, 154 insertions(+), 71 deletions(-)
> 
> diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> index 8c20361dd100..00350fc7c662 100644
> --- a/tools/objtool/Makefile
> +++ b/tools/objtool/Makefile
> @@ -34,7 +34,7 @@ INCLUDES := -I$(srctree)/tools/include \
>  # is passed here to match a legacy behavior.
>  WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
>  OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
> -OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
> +OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS) -lopcodes

Would it be possible to make this optional? Such that when people do not
have libopcodes installed they can still build the kernel.

Or is libopcodes a mandatory part of any binutils installation?