From mboxrd@z Thu Jan  1 00:00:00 1970
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [RFC][PATCH 0/5] preempt_count rework
Date: Wed, 14 Aug 2013 09:58:07 -0700
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References: <20130814131539.790947874@chello.nl> <520B8A81.1080405@zytor.com> <1376494751.7355.28.camel@marge.simpson.net> <20130814160632.GJ24092@twins.programming.kicks-ass.net> <520BACEA.50604@zytor.com> <20130814165227.GA21191@laptop.programming.kicks-ass.net>
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <bitbucket@online.de>, Linus Torvalds <torvalds@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>, Andi Kleen <ak@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, Arjan van de Ven <arjan@linux.intel.com>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org

On 08/14/2013 09:52 AM, Peter Zijlstra wrote:
> 
> Oh curses, this is because lea can't do segment offsets? So there's no
> sane way to get addresses of per-cpu variables.
> 
> Because ideally we'd have something like:
> 
>   lea %gs:__percpu_runqueues,%rax
> 
> So in this case it makes sense to also store the actual pointer; how
> unfortunate.
> 

Correct; the segment offset is not part of the effective address, even
in 64-bit mode.

	-hpa