Date: Sat, 09 Sep 2006 02:38:03 -0700 (PDT)
Message-Id: <20060909.023803.104047454.davem@davemloft.net>
To: benh@kernel.crashing.org
Cc: torvalds@osdl.org, paulus@samba.org, linux-kernel@vger.kernel.org,
       akpm@osdl.org, segher@kernel.crashing.org
Subject: Re: Opinion on ordering of writel vs. stores to RAM
From: David Miller <davem@davemloft.net>
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Sat, 09 Sep 2006 17:23:20 +1000

> I quite like mem_to_io_* (barrier/rb/wb) and io_to_mem_* in fact :) That
> is probably more talkative to device driver writers and would allow more
> fine grained barriers.

I firmly believe that the average driver person is not going
to be able to get these things right, even if you document it
in big bold letters in some Documentation/*.txt file.

This is like the Alpha OSF outb() interface for kernel drivers
that had something like 8 arguments.

And even if you define these things, and people start using it,
only PowerPC and a few other systems (I guess IA64) will ever
notice when this stuff is done wrong.  That's really not a good
plan from a testing coverage point of view.
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