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Date: Thu, 6 Nov 2008 08:12:06 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: akpm@linux-foundation.org, Pekka Enberg <penberg@cs.helsinki.fi>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org, travis@sgi.com,
       Stephen Rothwell <sfr@canb.auug.org.au>,
       Vegard Nossum <vegard.nossum@gmail.com>
Subject: Re: [patch 5/7] x86_64: Support for cpu ops
Message-ID: <20081106071206.GH15731@elte.hu>
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* Christoph Lameter <cl@linux-foundation.org> wrote:

> +#
> +# X86_64's spare segment register points to the PDA instead of the per
> +# cpu area. Therefore x86_64 is not able to generate atomic vs. interrupt
> +# per cpu instructions.
> +#
> +config HAVE_CPU_OPS
> +	def_bool y
> +	depends on X86_32
> +

hm, what happened to the rebase-PDA-to-percpu-area optimization 
patches you guys were working on? I remember there was some binutils 
flakiness - weird crashes and things like that. Did you ever manage to 
stabilize it? It would be sad if only 32-bit could take advantage of 
the optimized ops.

	Ingo