From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: ioctls, etc. (was Re: [PATCH 1/4] sas: add flag for locally attached PHYs) Date: Fri, 21 Oct 2005 20:04:55 +0200 Message-ID: <20051021180455.GA6834@lst.de> References: <91888D455306F94EBD4D168954A9457C048F0E34@nacos172.co.lsil.com> <20051020160155.GA14296@lst.de> <4357CB03.4020400@adaptec.com> <20051020170330.GA16458@lst.de> <4357F7DE.7050004@adaptec.com> <1129852879.30258.137.camel@bluto.andrew> <43583A53.2090904@pobox.com> <435929FD.4070304@adaptec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.210]:15041 "EHLO mail.lst.de") by vger.kernel.org with ESMTP id S965051AbVJUSGX (ORCPT ); Fri, 21 Oct 2005 14:06:23 -0400 Content-Disposition: inline In-Reply-To: <435929FD.4070304@adaptec.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Luben Tuikov Cc: Jeff Garzik , andrew.patterson@hp.com, Christoph Hellwig , "Moore, Eric Dean" , jejb@steeleye.com, linux-scsi@vger.kernel.org, Linux Kernel , Linus Torvalds On Fri, Oct 21, 2005 at 01:48:45PM -0400, Luben Tuikov wrote: > > why James has suggested implementing SMP as a block driver. People get > > stuck into thinking "block driver == block device", which is wrong. The ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > Linux block layer is nothing but a message queueing interface. > > Now, just because James suggested implementing the SMP service as a block > device you think this is the right thing to do? > > How about this: Why not as a char device? you can implement a char device using the block layer. See drivers/scsi/{ch.c,osst.c,sg.c,st.c} for examples. That beeing said I tried this approach. It looks pretty cool when you think about it, but the block layer is quite a bit too heavyweight for queueing up a few SMP requests, and we need to carry too much useless code around for it.