From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([66.187.233.31]:20613 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S964799AbWCHRUA (ORCPT ); Wed, 8 Mar 2006 12:20:00 -0500 From: David Howells In-Reply-To: <20060308154157.GI7301@parisc-linux.org> References: <20060308154157.GI7301@parisc-linux.org> <31492.1141753245@warthog.cambridge.redhat.com> <29826.1141828678@warthog.cambridge.redhat.com> <20060308145506.GA5095@devserv.devel.redhat.com> Subject: Re: [PATCH] Document Linux's memory barriers [try #2] Date: Wed, 08 Mar 2006 17:19:41 +0000 Message-ID: <10095.1141838381@warthog.cambridge.redhat.com> Sender: linux-arch-owner@vger.kernel.org To: Matthew Wilcox Cc: Alan Cox , David Howells , torvalds@osdl.org, akpm@osdl.org, mingo@redhat.com, linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org List-ID: Matthew Wilcox wrote: > > That might be worth an example with an if() because PPC will do this and > > if its a read with a side effect (eg I/O space) you get singed.. > > PPC does speculative memory accesses to IO? Are you *sure*? Can you do speculative reads from frame buffers? > # define smp_read_barrier_depends() do { } while(0) What's this one meant to do? > Port space is deprecated though. PCI 2.3 says: That's sort of irrelevant for the here. I still need to document the interaction. > Since memory write transactions may be posted in bridges anywhere > in the system, and I/O writes may be posted in the host bus bridge, I'm not sure whether this is beyond the scope of this document. Maybe the document's scope needs to be expanded. David