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Date: Tue, 15 Apr 2008 12:42:31 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Ben Hutchings <bhutchings@solarflare.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH][RFC] Add default CPU topology information
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On Mon, 31 Mar 2008 12:44:13 +0100
Ben Hutchings <bhutchings@solarflare.com> wrote:

> Not all architectures and configurations define CPU topology information.
> This can result in an empty topology directory in sysfs, and requires
> in-kernel users to protect all uses with #ifdef - see
> <http://marc.info/?l=linux-netdev&m=120639033904472&w=2>.
> 
> The documentation of CPU topology specifies what the defaults should be
> if only partial information is available from the hardware.  So we can
> provide these defaults as a fallback.
> 
> This patch:
> 
> - Adds default definitions of the 4 topology macros to
>   include/asm-generic/topology.h.
> - Changes include/asm-*/topology.h to include <asm-generic/topology.h>
>   unconditionally.
> - Changes drivers/base/topology.c to use the topology macros unconditionally
>   and to cope with definitions that aren't lvalues.
> - Updates documentation accordingly.
> 

I ran away in terror when I saw this patch.  It's dark and dirty stuff
you're unearthing there and it looks like a minefield of compilation
problems.  Not aided by the fact that we don't have a topology maintainer
afaik.  

We shall see.