linux-kernel - Re: [PATCH] cputopology: Always define CPU topology information [4th try]

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Date:	Wed, 16 Jul 2008 16:37:17 -0500
From:	Nathan Lynch <ntl@...ox.com>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Vegard Nossum <vegard.nossum@...il.com>
Subject: Re: [PATCH] cputopology: Always define CPU topology information [4th
 try]

Hi Ben-

Ben Hutchings 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.

I've been looking at adding topology information to powerpc and I came
across this.

I understand the need for fallback definitions of the topology APIs
within the kernel, but I'm not sure I agree with exposing these things
in sysfs unconditionally -- the default values for physical_package_id
and core_id don't really make sense on powerpc (and other non-x86
architectures, I suspect).

Would you object to a patch which exposes in sysfs only the topology
information which the architecture provides?
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