linux-kernel - Re: [PATCH v4 1/3] kbuild: add mod(name,file)_flags to assembler flags for module objects

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Message-ID: <ZmyHsnXQoWgp7F2X@oracle.com>
Date: Fri, 14 Jun 2024 14:10:58 -0400
From: Kris Van Hees <kris.van.hees@...cle.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Kris Van Hees <kris.van.hees@...cle.com>, linux-kernel@...r.kernel.org,
        linux-kbuild@...r.kernel.org, linux-modules@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.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 v4 1/3] kbuild: add mod(name,file)_flags to assembler
 flags for module objects

On Fri, Jun 14, 2024 at 01:46:51PM -0400, Steven Rostedt wrote:
> On Fri, 14 Jun 2024 13:14:26 -0400
> Kris Van Hees <kris.van.hees@...cle.com> wrote:
> 
> > Module objects compiled from C source can be identified by the presence
> > of -DKBUILD_MODFILE and -DKBUILD_MODNAME on their compile command lines.
> > However, module objects from assembler source do not have this defines.
> > 
> > Add $(modfile_flags) to modkern_aflags (similar to modkern_cflahs), and
> > add $(modname_flags) to a_flags (similar to c_flags).
> 
> You explain what this does but not why it does it.

The first paragraph is meant to estabish the "why" (being able to identify
what objects are module objects, even if they are compiled from assembler
source).

As I mention, for objects compiled from C source code, those defines being
present identifies those objects as belonging to a module.  For objects
compiled from assembler source code, those defines are not present.  Passing
them on the compile command line for assembler source code files for objects
that are part of one or more modules allows us to identify all objects that
are part of modules with a single consistent mechanism.

	Kris