From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756262AbXFSGH0 (ORCPT ); Tue, 19 Jun 2007 02:07:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752847AbXFSGHO (ORCPT ); Tue, 19 Jun 2007 02:07:14 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:45848 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752312AbXFSGHM (ORCPT ); Tue, 19 Jun 2007 02:07:12 -0400 Date: Mon, 18 Jun 2007 23:07:31 -0700 (PDT) Message-Id: <20070618.230731.11645150.davem@davemloft.net> To: hch@lst.de Cc: James.Bottomley@SteelEye.com, axboe@kernel.dk, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, paulus@samba.org, Geert.Uytterhoeven@sonycom.com, dwmw2@infradead.org, alan@lxorguk.ukuu.org.uk Subject: Re: [patch 4/6] ps3: Disk Storage Driver From: David Miller In-Reply-To: <20070619055629.GE18542@lst.de> References: <1181947242.3600.8.camel@mulgrave.il.steeleye.com> <20070615.160858.26276547.davem@davemloft.net> <20070619055629.GE18542@lst.de> X-Mailer: Mew version 5.1.52 on Emacs 21.4 / 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 X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Hellwig Date: Tue, 19 Jun 2007 07:56:29 +0200 > A SCSI pass through is of course perfectly fine. If you have a separate > block passthrough that has additional magic a separate block driver is > the way to go because it actually is simpler than a scsi driver decoding > command blocks and translating them to deep magic. The ps3 storage > drivers this thread discussed are a good example for that. We now > have a very nice and simple disk, scsi and flash chardev driver each > that don't include abstractions layers and cruft. Combine that with > their initial scsi layer driver that was full of internal dispatches > because each of these device types speaks a completely different command > set. That's how I'm currently writing my virtual disk client driver for the Sun LDOMS stuff, as a block device. The remaining issues are the partitioning (which we're discussing in another thread) and how to export the scsi passthru support in such a non-scsi block driver. The main disk I/O block read and write is done using descriptors sent to the disk server. SCSI pass-through is provided (optionally) so that disk analysis tools can do things like MODE_SENSE on the disk.