From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 4351EDDE08 for ; Wed, 22 Aug 2007 13:33:26 +1000 (EST) In-Reply-To: <20070822031506.GA26374@wotan.suse.de> References: <20070821021143.GB2909@wotan.suse.de> <46CB37D4.2080609@austin.ibm.com> <20070822031506.GA26374@wotan.suse.de> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <1afbd9c8892724e484f29532802a3405@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [patch 1/2] powerpc: rmb fix Date: Wed, 22 Aug 2007 05:33:16 +0200 To: Nick Piggin Cc: linuxppc-dev@ozlabs.org, Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >> The I/O accessor functions enforce the necessary ordering >> already I believe. > > Hmm, I never followed those discussions last year about IO ordering, > and > I can't see where (if) it was documented anywhere :( The comments in system.h weren't updated with the last fix, I think. > It appears that legacy code is handled by defining the old IO > accessors to > be completely ordered, and introducing new __raw_ variants that are not > (OTOH, it seems like other architectures are implementing __raw prefix > as > inorder unless there is a _relaxed postfix). __raw_XX() is for platform code only, which can do the needed barriers without having to use the heavy hammer like everything else unfortunately does. > Drivers are definitely using these __raw_ accessors, and from a quick > look, they do appear to be hoping that *mb() is going to order access > for > them. Which drivers? Segher