Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 25 Aug 2021 17:34:37 +0200
From:   Boris Kolpackov <boris@codesynthesis.com>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     linux-kbuild@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        Kalle Valo <kvalo@codeaurora.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Luca Coelho <luciano.coelho@intel.com>,
        Mark Brown <broonie@kernel.org>,
        Peter Ujfalusi <peter.ujfalusi@gmail.com>,
        Takashi Iwai <tiwai@suse.com>, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org
Subject: Re: [PATCH] kconfig: forbid symbols that end with '_MODULE'
Message-ID: <boris.20210825172545@codesynthesis.com>
References: <20210825041637.365171-1-masahiroy@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210825041637.365171-1-masahiroy@kernel.org>
Organization: Code Synthesis
User-Agent: Mutt/1.5.24 (2015-08-30)
Precedence: bulk

Masahiro Yamada <masahiroy@kernel.org> writes:

> Kconfig (syncconfig) generates include/generated/autoconf.h to make
> CONFIG options available to the pre-processor.
> 
> The macros are suffixed with '_MODULE' for symbols with the value 'm'.
> 
> Here is a conflict; CONFIG_FOO=m results in '#define CONFIG_FOO_MODULE 1',
> but CONFIG_FOO_MODULE=y also results in the same define.
> 
> fixdep always assumes CONFIG_FOO_MODULE comes from CONFIG_FOO=m, so the
> dependency is not properly tracked for symbols that end with '_MODULE'.

It seem to me the problem is in autoconf.h/fixdep, not in the Kconfig
language.


> This commit makes Kconfig error out if it finds a symbol suffixed with
> '_MODULE'.

I know you don't care, but I will voice my objection, for the record:
Kconfig is used by projects other than the Linux kernel and some of
them do not use the autoconf.h functionality. For such projects this
restriction seems arbitrary and potentially backwards-incompatible.