From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762661AbXKTWj4 (ORCPT ); Tue, 20 Nov 2007 17:39:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759210AbXKTWjp (ORCPT ); Tue, 20 Nov 2007 17:39:45 -0500 Received: from gate.crashing.org ([63.228.1.57]:60801 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758634AbXKTWjo (ORCPT ); Tue, 20 Nov 2007 17:39:44 -0500 Subject: Re: SCSI breakage on non-cache coherent architectures From: Benjamin Herrenschmidt Reply-To: benh@kernel.crashing.org To: James Bottomley Cc: Roland Dreier , Thomas Bogendoerfer , David Miller , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, rmk@arm.linux.org.uk In-Reply-To: <1195593015.17601.10.camel@localhost.localdomain> References: <1195450523.7022.37.camel@pasglop> <20071119.003802.100741794.davem@davemloft.net> <1195501874.6539.5.camel@pasglop> <20071120082927.GA8856@alpha.franken.de> <1195569362.3131.3.camel@localhost.localdomain> <1195593015.17601.10.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 21 Nov 2007 09:39:03 +1100 Message-Id: <1195598343.6970.50.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-11-20 at 15:10 -0600, James Bottomley wrote: > We're talking about trying to fix this for 2.4; which is already at > -rc3 ... Is an entire arch change for dma alignment really a merge > candidate at this stage? Well, as I said before... it's a matter of what seems to be the less likely to break something right ? On one side, I'm doing surgery on code I barely know, the scsi error handling, and now it seems I also have to fixup a handful of drivers that aren't the most obvious pieces of code around. On the other side, Roland proposal is basically just adding a macro that can be empty for everybody but a handful of archs, and stick it onto one field in one structure... The later has about 0 chances to actually break something or cause a regression. I wouldn't say that about the former. Now, I will see if I manage to fixup the NCR drivers to pass a pre-allocated buffer (USB storage I think can pass NULL as it's not calling prep in atomic context). But then, it complicates the matter because that means "restore" will have to know whether prep allocated the buffer or not, thus more fields to add to the save struct, it's getting messy, unless we decide -all- callers are responsible for the buffer allocation (hrm... maybe the best approach). Ben.