From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lst.de (verein.lst.de [213.95.11.210]) (using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 370FEDDEE4 for ; Tue, 19 Jun 2007 15:56:38 +1000 (EST) Date: Tue, 19 Jun 2007 07:56:29 +0200 From: Christoph Hellwig To: David Miller Subject: Re: [patch 4/6] ps3: Disk Storage Driver Message-ID: <20070619055629.GE18542@lst.de> References: <20070615171545.316dfac7@the-village.bc.nu> <20070615.141917.85409547.davem@davemloft.net> <1181947242.3600.8.camel@mulgrave.il.steeleye.com> <20070615.160858.26276547.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20070615.160858.26276547.davem@davemloft.net> 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 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Jun 15, 2007 at 04:08:58PM -0700, David Miller wrote: > That's not gonna work, it's a totally different model. > > I have a predefined protocol over hypervisor provided "channels" and > page flipping also done by the hypervisor for the bulk data transfer. > For the client side I cannot change the hypervisor nor the server > speaking on the other end. And when I do write a server I do want > it to be able to speak to all of the existing clients. > > There's SCSI command pass through as well, as I keep mentioning as > it's an important reason I don't want to go with any of the non-SCSI > solutions (other than perhaps ATA) being suggested. 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.