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From:   Dmitrii Bundin <dmitrii.bundin.a@gmail.com>
Date:   Tue, 23 Aug 2022 01:42:41 +0300
Message-ID: <CANXV_XzdTTYc2w7Ur8zY=ijOofg91yfF7RLhedbVH0rmi3c2yA@mail.gmail.com>
Subject: Re: [PATCH v3] kbuild: add debug level and macro defs options
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Eric Dumazet <edumazet@google.com>,
        Isabella Basso <isabbasso@riseup.net>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Fangrui Song <maskray@google.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nathan Chancellor <nathan@kernel.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>
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On Tue, Aug 23, 2022 at 12:36 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> or perhaps that simply needs to be `-g -gsplit-dwarf`?  In which case,
> that if/else could just be re-arranged.

How about simply assigning DEBUG_CFLAGS   := -g at the very beginning
without any conditions? This would provide the default with the
possibility of overriding later and -gsplit-dwarf does not necessarily
come with -g implicitly.

> Honestly, I really don't think we need to be wrapping every compiler
> command line flag under the sun in a kconfig option.

This indeed sounds reasonable to me. So the key point here is to not
bloat the kconfig with options related to every compiler flag. But I
think it still might be useful to provide some option that would
include sort of full debug information compilers may produce. With
this approach there would be, in fact 3 different levels of debug
information supported by Kconfig: reduced, default and full. The full
level would increase everything like -g3, and -fdebug-macro for Clang,
and probably others.

> Or add -g1 to CONFIG_DEBUG_INFO_REDUCED.

I ran some tests and there was indeed some decrease in size. That
combination probably might be useful.

Any thoughts?

Regards
Dmitrii