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Date: Tue, 12 Feb 2002 17:47:11 -0800
From: "Brian J. Watson" <Brian.J.Watson@compaq.com>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: marcelo@conectiva.com.br, linux-kernel@vger.kernel.org,
        dhowells@redhat.com, hch@caldera.de
Subject: Re: [PATCH] 2.4.18-pre9, trylock for read/write semaphores
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Alan Cox wrote:
> 
> > +     new = old + RWSEM_ACTIVE_READ_BIAS;
> > +     if (cmpxchg(&sem->count, old, new) == old)
> > +             return 1;
> 
> cmpxchg isnt present on i386


According to arch/i386/config.in, the generic spinlock version would be
used for vintage 386 chips. I think that's due to similar concerns about
the xadd instruction.

-- 
Brian Watson                | "Now I don't know, but I been told it's
Linux Kernel Developer      |  hard to run with the weight of gold,
Open SSI Clustering Project |  Other hand I heard it said, it's
Compaq Computer Corp        |  just as hard with the weight of lead."
Los Angeles, CA             |     -Robert Hunter, 1970

mailto:Brian.J.Watson@compaq.com
http://opensource.compaq.com/
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