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Message-ID: <6b507126-c4e6-40f2-9574-fe1abb0463ee@infradead.org>
Date:   Fri, 15 Sep 2023 08:48:08 -0700
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Subject: Re: [PATCH] Documentation: kbuild: explain handling optional
 dependencies
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To:     Arnd Bergmann <arnd@arndb.de>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Masahiro Yamada <masahiroy@kernel.org>
Cc:     Arnd Bergmann <arnd@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
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From:   Randy Dunlap <rdunlap@infradead.org>
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On 9/15/23 00:44, Arnd Bergmann wrote:
> On Fri, Sep 15, 2023, at 09:34, Jani Nikula wrote:
>>
>> IS_REACHABLE() considered harmful.
> 

+1 absolutely.

> Absolutely agreed, and I'm sorry I introduced it in the
> first place in commit 9b174527e7b75 ("[media] Add and use
> IS_REACHABLE macro").
> 
> At the time, it was only used by drivers/media, which used
> to have a lot of open-coded instances of it and a lot of
> wrong checks.
> 
> Having a formal syntax for it was an improvement for
> drivers/media since it was more broken before, but it's
> usually a mistake to use it when there is another solution,
> and we probably should have tried harder to fix the
> dependencies in drivers/media at the time.
> 
>       Arnd

-- 
~Randy