linux-kernel - Re: MMIO and gcc re-ordering issue

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Date:	Fri, 30 May 2008 11:13:23 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
Cc:	Matthew Wilcox <matthew@....cx>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Miller <davem@...emloft.net>, linux-arch@...r.kernel.org,
	scottwood@...escale.com, linuxppc-dev@...abs.org,
	alan@...rguk.ukuu.org.uk, linux-kernel@...r.kernel.org,
	tpiepho@...escale.com
Subject: Re: MMIO and gcc re-ordering issue


> I do -- in all the drivers for on-chip peripherals that are shared
> between AT91 ARM (LE) and AVR32 (BE). Since everything goes on inside
> the chip, we must use LE accesses on ARM and BE accesses on AVR32.
> 
> Currently, this is the only interface I know that can do native-endian
> accesses, so if you take it away, I'm gonna need an alternative
> interface that doesn't do byteswapping.

Are you aware that these also don't provide any ordering guarantee ?

Ben.


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