linux-kernel - Re: WARNING: at arch/x86/kernel/smpboot.c:310 topology

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Message-ID: <1338310743.26856.141.camel@twins>
Date:	Tue, 29 May 2012 18:59:03 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Borislav Petkov <bp@...64.org>, Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, hpa <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: WARNING: at arch/x86/kernel/smpboot.c:310
 topology_sane.clone.1+0x6e/0x81()

On Tue, 2012-05-29 at 17:29 +0200, Andreas Herrmann wrote:

> I've also looked at this. core_siblings mask is broken with this patch.
> And there is this new irritating warning ...

Hehe, you made this irritating hardware ;-) But fair enough.

> I second Boris' suggestion for a fix. But I think the check for
> X86_FEATURE_AMD_DCM should go into topology_sane() which in theory
> could check other things as well.

Unless you plan to go span cache (or even SMT siblings) over physical
IDs I'd strongly argue against putting it in topology_sane().

As it stands I think we should discuss the definition for the generic
topology bits (drivers/base/topology.c), because I think your
Magny-Cours thing does the wrong thing here.

The core span in a phys_id is all nice and such, but what does it mean?
IOW what would you do with it?

I would think the LLC range and the node-span are much more useful
things to have. Once you have nodes the sysfs node topology takes over.

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