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Date: Mon, 23 Sep 2002 13:57:08 -0700 (PDT)
Message-Id: <20020923.135708.10698522.davem@redhat.com>
To: davidm@hpl.hp.com, davidm@napali.hpl.hp.com
Cc: dmo@osdl.org, axboe@suse.de, phillips@arcor.de, _deepfire@mail.ru,
       linux-kernel@vger.kernel.org
Subject: Re: DAC960 in 2.5.38, with new changes
From: "David S. Miller" <davem@redhat.com>
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   From: David Mosberger <davidm@napali.hpl.hp.com>
   Date: Mon, 23 Sep 2002 13:53:13 -0700
   
     > Or perhaps every platform should provide a writeq(), on 32-bit systems
     > it may merely be implemented as two consequetive writel() calls.
   
   True, but I was wondering whether driver writers will have an implicit
   assumption on readX/writeX being atomic.  I don't think anyone ever
   promised that, but I suspect all existing implementations are indeed
   atomic (it's true even for old Alphas which don't have sub-word
   load/stores).
   
On many platforms, two consequetive __raw_writel()'s might even
combine to an atomic 64-bit store to PCI space. :-)

I don't think the proposed 32-bit behavior is off the mark, and
anyways x86 can actually make the 64-bit store I believe if it
wants at least on more recent processors.
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