From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pentafluge.infradead.org (pentafluge.infradead.org [213.146.154.40]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id C7A43DDF87 for ; Tue, 27 May 2008 14:27:21 +1000 (EST) Date: Mon, 26 May 2008 21:20:10 -0700 From: Arjan van de Ven To: Roland Dreier Subject: Re: MMIO and gcc re-ordering issue Message-ID: <20080526212010.664302cf@infradead.org> In-Reply-To: References: <1211852026.3286.36.camel@pasglop> <20080526.184047.88207142.davem@davemloft.net> <1211854540.3286.42.camel@pasglop> <20080526.192812.184590464.davem@davemloft.net> <20080526204233.75b71bb8@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, tpiepho@freescale.com, linuxppc-dev@ozlabs.org, scottwood@freescale.com, torvalds@linux-foundation.org, David Miller , alan@lxorguk.ukuu.org.uk List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 26 May 2008 21:08:10 -0700 Roland Dreier wrote: > > either via sparse or some fancy lockdep like "device store" thing? > > If we can't test for it and it doesn't show up on x86 ... it'll > > just be an eterrnal chase. > > Ben's point is that it will start showing up on x86 because newer > compilers are reordering things... > > - R. I know a basic reorder will show up there. A simple "barrier()" in readl/writel solves it for x86. Understandably, Ben doesn't really like that answer ;-) -- If you want to reach me at my work email, use arjan@linux.intel.com For development, discussion and tips for power savings, visit http://www.lesswatts.org