From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: SCSI breakage on non-cache coherent architectures Date: Tue, 20 Nov 2007 06:51:14 +1100 Message-ID: <1195501874.6539.5.camel@pasglop> References: <1195450523.7022.37.camel@pasglop> <20071119.003802.100741794.davem@davemloft.net> Reply-To: benh@kernel.crashing.org Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from gate.crashing.org ([63.228.1.57]:59760 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbXKSTvp (ORCPT ); Mon, 19 Nov 2007 14:51:45 -0500 In-Reply-To: <20071119.003802.100741794.davem@davemloft.net> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: David Miller Cc: James.Bottomley@HansenPartnership.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, rmk@arm.linux.org.uk 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 ? Cheers, Ben.