From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Carstens Subject: Re: Proposals to change the way all drivers work with SCSI commands Date: Sat, 12 May 2007 11:12:44 +0200 Message-ID: <20070512091244.GA7981@osiris.boeblingen.de.ibm.com> References: <1178908422.3692.58.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mtagate1.uk.ibm.com ([195.212.29.134]:58724 "EHLO mtagate1.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754516AbXELJNX (ORCPT ); Sat, 12 May 2007 05:13:23 -0400 Received: from d06nrmr1407.portsmouth.uk.ibm.com (d06nrmr1407.portsmouth.uk.ibm.com [9.149.38.185]) by mtagate1.uk.ibm.com (8.13.8/8.13.8) with ESMTP id l4C9DMWt166454 for ; Sat, 12 May 2007 09:13:22 GMT Received: from d06av01.portsmouth.uk.ibm.com (d06av01.portsmouth.uk.ibm.com [9.149.37.212]) by d06nrmr1407.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l4C9DMNp2773034 for ; Sat, 12 May 2007 10:13:22 +0100 Received: from d06av01.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av01.portsmouth.uk.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l4C8Bx1U000368 for ; Sat, 12 May 2007 09:11:59 +0100 Content-Disposition: inline In-Reply-To: <1178908422.3692.58.camel@mulgrave.il.steeleye.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: linux-scsi On Fri, May 11, 2007 at 01:33:41PM -0500, James Bottomley wrote: > It strikes me that in all of this, we could also consider doing the DMA > mapping inside the mid layer (instead of in every driver). This is > essentially what libata is already doing ... leading to confusion in > SCSI drivers that use libata for SATA. > > So what do people think about this? I hope that doesn't mean that each architecture is required to implement all the DMA mapping stuff? s390 doesn't have any support for DMA at all. The current workaround seems to be to sprinkle a lot of BUG() statements in code that simply won't work on such architectures but still compile it in. Lately I introduced CONFIG_HAS_DMA and made building drivers/base/dma-mapping.o and dmapool.o depend on that, so we don't compile all the non working stuff on s390. Hope all that can be sorted out if you go that direction.