From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support Date: Fri, 1 May 2009 12:08:06 +0100 Message-ID: <20090501110805.GA15311@shareable.org> References: <20090427082606.GA32604@lst.de> <200904291237.21558.paul@codesourcery.com> <20090430201350.GA30619@lst.de> <200904302249.20940.paul@codesourcery.com> <20090501072449.GA21867@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Paul Brook , kvm@vger.kernel.org, Rusty Russell , qemu-devel@nongnu.org, Christian Borntraeger , Hannes Reinecke To: Christoph Hellwig Return-path: Received: from mail2.shareable.org ([80.68.89.115]:49430 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751006AbZEALIN (ORCPT ); Fri, 1 May 2009 07:08:13 -0400 Content-Disposition: inline In-Reply-To: <20090501072449.GA21867@lst.de> Sender: kvm-owner@vger.kernel.org List-ID: Christoph Hellwig wrote: > On Thu, Apr 30, 2009 at 10:49:19PM +0100, Paul Brook wrote: > > Only if you emulate a crufty old parallel scsi bus, and that's just silly. > > One of the nice things about scsi is it separates the command set from the > > transport layer. cf. USB mass-storage, SAS, SBP2(firewire), and probably > > several others I've forgotten. > > It has nothing to do with an SPI bus. Everything that resembles a SAM > architecture can have multiple LUs per targer, and multiple targers per > initiator port, so we need all the complex queing code, and we need > error handling and and and. If you're using virtio-block to connect to lots of LUNs on lots of targets (i.e. lots of block devices), don't you need similar queuing code and error handling for all that too? -- Jamie From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LzqbQ-0003TO-QO for qemu-devel@nongnu.org; Fri, 01 May 2009 07:08:24 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LzqbL-0003Lk-FQ for qemu-devel@nongnu.org; Fri, 01 May 2009 07:08:23 -0400 Received: from [199.232.76.173] (port=56744 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LzqbK-0003LW-9k for qemu-devel@nongnu.org; Fri, 01 May 2009 07:08:18 -0400 Received: from mail2.shareable.org ([80.68.89.115]:60064) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LzqbJ-0002YU-Fh for qemu-devel@nongnu.org; Fri, 01 May 2009 07:08:17 -0400 Date: Fri, 1 May 2009 12:08:06 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support Message-ID: <20090501110805.GA15311@shareable.org> References: <20090427082606.GA32604@lst.de> <200904291237.21558.paul@codesourcery.com> <20090430201350.GA30619@lst.de> <200904302249.20940.paul@codesourcery.com> <20090501072449.GA21867@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090501072449.GA21867@lst.de> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: kvm@vger.kernel.org, Rusty Russell , qemu-devel@nongnu.org, Christian Borntraeger , Hannes Reinecke , Paul Brook Christoph Hellwig wrote: > On Thu, Apr 30, 2009 at 10:49:19PM +0100, Paul Brook wrote: > > Only if you emulate a crufty old parallel scsi bus, and that's just silly. > > One of the nice things about scsi is it separates the command set from the > > transport layer. cf. USB mass-storage, SAS, SBP2(firewire), and probably > > several others I've forgotten. > > It has nothing to do with an SPI bus. Everything that resembles a SAM > architecture can have multiple LUs per targer, and multiple targers per > initiator port, so we need all the complex queing code, and we need > error handling and and and. If you're using virtio-block to connect to lots of LUNs on lots of targets (i.e. lots of block devices), don't you need similar queuing code and error handling for all that too? -- Jamie