Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756525Ab2BGOAK (ORCPT ); Tue, 7 Feb 2012 09:00:10 -0500 Received: from e06smtp17.uk.ibm.com ([195.75.94.113]:54277 "EHLO e06smtp17.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756225Ab2BGOAG convert rfc822-to-8bit (ORCPT ); Tue, 7 Feb 2012 09:00:06 -0500 In-Reply-To: <4F312492.1040002@de.ibm.com> References: <4F30F4EE.4080607@redhat.com> <4F311154.9080407@de.ibm.com> <4F3119A0.7080005@redhat.com> <4F312492.1040002@de.ibm.com> To: BORNTRAE@linux.vnet.ibm.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, mst@redhat.com, Paolo Bonzini , rusty@rustcorp.com.au MIME-Version: 1.0 Subject: Re: Pe: [PATCH v5 1/3] virtio-scsi: first version X-KeepSent: AFB86CAE:9917478D-C125799D:004AF231; type=4; name=$KeepSent X-Mailer: Lotus Notes Release 8.5.2FP3 Aug 10, 2010 Message-ID: From: Christian Hoff Date: Tue, 7 Feb 2012 14:59:53 +0100 X-MIMETrack: S/MIME Sign by Notes Client on Christian Hoff/Germany/IBM(Release 8.5.2FP3|Aug 10, 2010) at 07/02/2012 14:59:58, Serialize by Notes Client on Christian Hoff/Germany/IBM(Release 8.5.2FP3|Aug 10, 2010) at 07/02/2012 14:59:58, Serialize complete at 07/02/2012 14:59:58, S/MIME Sign failed at 07/02/2012 14:59:58: The cryptographic key was not found, Serialize by Router on D06MC042/06/M/IBM(Release 8.5.2FP3|July 10, 2011) at 07/02/2012 14:59:55, Serialize complete at 07/02/2012 14:59:55 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8BIT x-cbid: 12020714-0542-0000-0000-000000EB679D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2545 Lines: 87 Hello Paolo, On 07/02/12 13:31, Paolo Bonzini wrote: > The structure of the LUN is defined by SAM, not by me. Just had a look at the SAM LUN structure. It appears that you are using the SCSI format for hierarchical LUNs(SAM 5 chapter 4.7.6) in order to indicate that the LUN is actually attached to the host system and not to the Qemu guest operating system itself. What I am wondering is why you are doing this? The hierarchical SCSI format is only retained while the LUN number is being transmitted over the virtqueue, so there does not seem to be a technical necessity for using this format in order to transmit SCSI target ID and LUN number information to the host. Instead the format has some disadvantages: - It uses up 8 bytes where 3 bytes would be sufficient in order to store both the target ID and LUN number information - The format limits us to 255 target IDs. I agree that the LUN limit is probably more a theoretical and not a practical one, but 255 target IDs could become a limitation in the future. Nonetheless I think that virtio-scsi is a useful project and addresses many of the limitations imposed by virtio-block. The fact that I am still persisting has more to do with interest in the project rather than wanting to keep the code from going upstream. Thank you for your work on this topic. Mit freundlichen Gr??en / Kind regards Christian Hoff Student - Applied Computer Science Phone: 49-16098976-950 IBM Deutschland E-Mail: christian.hoff@de.ibm.com Am Fichtenberg 1 71083 Herrenberg Germany IBM Deutschland GmbH / Vorsitzender des Aufsichtsrats: Martin Jetter Gesch?ftsf?hrung: Martina Koederitz (Vorsitzende), Reinhard Reschke, Dieter Scholz, Gregor Pillen, Joachim Heel, Christian Noll Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart, HRB 14562 / WEEE-Reg.-Nr. DE 99369940 From: BORNTRAE@linux.vnet.ibm.com To: Paolo Bonzini Cc: Christian Hoff/Germany/IBM@IBMDE, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, rusty@rustcorp.com.au, mst@redhat.com, kvm@vger.kernel.org Date: 07/02/2012 14:18 Subject: Re: Pe: [PATCH v5 1/3] virtio-scsi: first version On 07/02/12 13:31, Paolo Bonzini wrote: > The structure of the LUN is defined by SAM, not by me. Ok, got it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/