From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752230AbYD0Wq3 (ORCPT ); Sun, 27 Apr 2008 18:46:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752038AbYD0WqV (ORCPT ); Sun, 27 Apr 2008 18:46:21 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36269 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752034AbYD0WqV (ORCPT ); Sun, 27 Apr 2008 18:46:21 -0400 Date: Sun, 27 Apr 2008 15:46:20 -0700 (PDT) Message-Id: <20080427.154620.177583216.davem@davemloft.net> To: jeff@garzik.org Cc: James.Bottomley@HansenPartnership.com, mingo@elte.hu, tglx@linutronix.de, linux-kernel@vger.kernel.org, hpa@zytor.com, torvalds@linux-foundation.org Subject: Re: [patch] x86, voyager: fix ioremap_nocache() From: David Miller In-Reply-To: <4815009C.2010809@garzik.org> References: <20080427214837.GA11631@elte.hu> <1209335660.3801.79.camel@localhost.localdomain> <4815009C.2010809@garzik.org> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeff Garzik Date: Sun, 27 Apr 2008 18:39:24 -0400 > I disagree with this semantics change. A number of code places _and > drivers_ GET IT RIGHT, and these are all broken now? [ Note, James's patch that you quoted is about mapping DMA memory, in dma_declare_coherent_memory(), rather than devices. But I know what you are trying to talk about Jeff. :-) ] Wrt. ioremap() semanics, it is important to realize that if the implementation of this on x86 has been giving non-cached I/O mappings out up until recently, you can expect that there are hundreds of drivers that might now be broken. That's the sad fact of the ubiquity of x86, and it doesn't matter how we defined the API is some document. Anyways, my point is that this angle should be strongly considered in any discussion about ioremap() behavior.