From mboxrd@z Thu Jan 1 00:00:00 1970 From: tsbogend@alpha.franken.de (Thomas Bogendoerfer) Subject: Re: SCSI breakage on non-cache coherent architectures Date: Tue, 20 Nov 2007 09:29:28 +0100 Message-ID: <20071120082927.GA8856@alpha.franken.de> References: <1195450523.7022.37.camel@pasglop> <20071119.003802.100741794.davem@davemloft.net> <1195501874.6539.5.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from elvis.franken.de ([193.175.24.41]:36457 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755675AbXKTJjL (ORCPT ); Tue, 20 Nov 2007 04:39:11 -0500 Content-Disposition: inline In-Reply-To: <1195501874.6539.5.camel@pasglop> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Benjamin Herrenschmidt Cc: David Miller , James.Bottomley@HansenPartnership.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, rmk@arm.linux.org.uk On Tue, Nov 20, 2007 at 06:51:14AM +1100, Benjamin Herrenschmidt wrote: > > On Mon, 2007-11-19 at 00:38 -0800, David Miller wrote: > > From: Benjamin Herrenschmidt > > Date: Mon, 19 Nov 2007 16:35:23 +1100 > > > > > I'm not sure what is the best way to fix that. Internally, I've done > > > some test whacking some ____cacheline_aligned in the scsi_cmnd data > > > structure to verify I no longer get random SLAB corruption when using my > > > USB but that significantly bloats the size of the structure on archs > > > such as ppc64 that don't need it and have a large cache line size. > > > > > > Unfortunately, I don't think there's any existing Kconfig symbol or arch > > > provided #define to tell us that we are on a non-coherent arch afaik > > > that could be used to make that conditional. > > > > > > Another option would be to kmalloc the buffer (wasn't it the case before > > > btw ?) but I suppose some people will scream at the idea due to how the > > > command pools are done... > > > > You could make a ____dma_cacheline_aligned and use that. > > It seems pretty reasonable. > > I was thinking about that. What archs would need it ? arm, mips, what > else ? older parisc Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessary a good idea. [ RFC1925, 2.3 ]