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Date: Fri, 17 Feb 2012 12:30:37 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>, linux-next@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH] mm: add config NUMA stub to all architectures
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On Fri, 17 Feb 2012 16:08:15 +0400
Konstantin Khlebnikov <khlebnikov@openvz.org> wrote:

> Config NUMA must be defined for all architectures,
> otherwise IS_ENABLED(CONFIG_NUMA) does not work.
> Some arch-specific Kconfig already has this stub.
> This patch adds it to all remaining.

It would be better to teach IS_ENABLED() to handle this situation.  I
don't think there's a way of doing this with cpp :(

This limitation makes IS_ENABLED pretty dangerous, doesn't it?  It
makes it very easy to introduce build breakage with unexpected Kconfig
combinations.