linux-kernel - Re: [PATCH 12/17] x86-64: Use absolute displacements for per-cpu accesses.

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Date:	Sun, 18 Jan 2009 13:22:09 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Brian Gerst <brgerst@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/17] x86-64: Use absolute displacements for per-cpu
 accesses.

Hello, Brian.

Brian Gerst wrote:
> Accessing memory through %gs should not use rip-relative addressing.
> Adding a P prefix for the argument tells gcc to not add (%rip) to
> the memory references.

Nice catch.  I dind't know about the P prefix thing.  It also is used
in other places too.  Hmmm... I can't find anything about the P
argument prefix in the gcc info page (4.3).  Any ideas where I can
find some information about it?  It's a bit weird that it's not a
constraint prefix but an argument one.

Thanks.

-- 
tejun
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