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 Grüßen / Kind regards Christian Hoff Student - Applied Computer Science Phone: 49-16098976-950 IBM Deutschland E-Mail: christian.hoff@xxxxxxxxxx Am Fichtenberg 1 71083 Herrenberg Germany IBM Deutschland GmbH / Vorsitzender des Aufsichtsrats: Martin Jetter Geschäftsführung: 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@xxxxxxxxxxxxxxxxxx To: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Christian Hoff/Germany/IBM@IBMDE, linux-kernel@xxxxxxxxxxxxxxx, linux-scsi@xxxxxxxxxxxxxxx, rusty@xxxxxxxxxxxxxxx, mst@xxxxxxxxxx, kvm@xxxxxxxxxxxxxxx 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-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
