linux-kernel - Re: [PATCH v8 1/4] kbuild: add mod(name,file)_flags to assembler flags for module objects

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Message-ID: <CAK7LNATrCQb23mnc4nHQ3OEWRf+6gB_32+3x84BtYmV6xTRHyQ@mail.gmail.com>
Date: Sat, 24 Aug 2024 02:37:19 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Kris Van Hees <kris.van.hees@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org, 
	linux-modules@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	Steven Rostedt <rostedt@...dmis.org>, Luis Chamberlain <mcgrof@...nel.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Jiri Olsa <olsajiri@...il.com>, Elena Zannoni <elena.zannoni@...cle.com>
Subject: Re: [PATCH v8 1/4] kbuild: add mod(name,file)_flags to assembler
 flags for module objects

On Fri, Aug 23, 2024 at 3:21 AM Kris Van Hees <kris.van.hees@...cle.com> wrote:
>
> In order to create the file at build time, modules.builtin.ranges, that
> contains the range of addresses for all built-in modules, there needs to
> be a way to identify what code is compiled into modules.
>
> To identify what code is compiled into modules during a kernel build,
> one can look for the presence of the -DKBUILD_MODFILE and -DKBUILD_MODNAME
> options in the compile command lines.  A simple grep in .*.cmd files for
> those options is sufficient for this.
>
> Unfortunately, these options are only passed when compiling C source files.
> Various modules also include objects built from assembler source, and these
> options are not passed in that case.
>
> Adding $(modfile_flags) to modkern_aflags (similar to modkern_cflahs), and


modkern_cflahs  ->  modkern_cflags


> adding $(modname_flags) to a_flags (similar to c_flags) makes it possible
> to identify which objects are compiled into modules for both C and
> assembler soure files.

soure  -> source



Strictly speaking, only KBUILD_MODFILE was used in 2/4 or 3/4.

KBUILD_MODNAME was unneeded, but If you want to add KBUILD_MODNAME
for consistency, it is fine too.


RUST_MODFILE exists, but RUST_MODNAME does not.



>
> Signed-off-by: Kris Van Hees <kris.van.hees@...cle.com>
> Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> ---
>  scripts/Makefile.lib | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index fe3668dc4954..170f462537a8 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -238,7 +238,7 @@ modkern_rustflags =                                              \
>
>  modkern_aflags = $(if $(part-of-module),                               \
>                         $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE),       \
> -                       $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL))
> +                       $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL) $(modfile_flags))
>
>  c_flags        = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
>                  -include $(srctree)/include/linux/compiler_types.h       \
> @@ -248,7 +248,7 @@ c_flags        = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
>  rust_flags     = $(_rust_flags) $(modkern_rustflags) @$(objtree)/include/generated/rustc_cfg
>
>  a_flags        = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
> -                $(_a_flags) $(modkern_aflags)
> +                $(_a_flags) $(modkern_aflags) $(modname_flags)
>
>  cpp_flags      = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
>                  $(_cpp_flags)
> --
> 2.45.2
>


-- 
Best Regards
Masahiro Yamada