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Subject: Re: [RFC PATCH 02/33] Add sync bitops
From: Arjan van de Ven <arjan@infradead.org>
To: Chris Wright <chrisw@sous-sol.org>
Cc: linux-kernel@vger.kernel.org, virtualization@lists.osdl.org,
       xen-devel@lists.xensource.com, Jeremy Fitzhardinge <jeremy@goop.org>,
       Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
       Rusty Russell <rusty@rustcorp.com.au>, Zachary Amsden <zach@vmware.com>,
       Ian Pratt <ian.pratt@xensource.com>,
       Christian Limpach <Christian.Limpach@cl.cam.ac.uk>,
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	 <20060718091948.747619000@sous-sol.org>
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Organization: Intel International BV
Date: Tue, 18 Jul 2006 11:56:41 +0200
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On Tue, 2006-07-18 at 00:00 -0700, Chris Wright wrote:
> plain text document attachment (synch-ops)
> Add "always lock'd" implementations of set_bit, clear_bit and
> change_bit and the corresponding test_and_ functions.  Also add
> "always lock'd" implementation of cmpxchg.  These give guaranteed
> strong synchronisation and are required for non-SMP kernels running on
> an SMP hypervisor.

Hi,

this sounds really like the wrong approach; you know you're compiling
for xen, so why not just make set_bit() and the others use the lock'd
instructions at compile time? 

Greetings,
    Arjan van de Ven