From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753614Ab1LCRiO (ORCPT ); Sat, 3 Dec 2011 12:38:14 -0500 Received: from mail-bw0-f46.google.com ([209.85.214.46]:61588 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753360Ab1LCRiN (ORCPT ); Sat, 3 Dec 2011 12:38:13 -0500 Message-ID: <4EDA5E7F.30508@redhat.com> Date: Sat, 03 Dec 2011 18:38:07 +0100 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 MIME-Version: 1.0 To: Benjamin Herrenschmidt CC: "Michael S. Tsirkin" , LKML , Rusty Russell , Stefan Hajnoczi Subject: Re: [PATCH 1/2] virtio-scsi: first version References: <1322661299-28855-1-git-send-email-pbonzini@redhat.com> <1322661299-28855-2-git-send-email-pbonzini@redhat.com> <1322867228.11728.19.camel@pasglop> In-Reply-To: <1322867228.11728.19.camel@pasglop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2011 12:07 AM, Benjamin Herrenschmidt wrote: > This is typically the one thing you should -really- obtain from the > other side. This is the number one reason why we cannot today reliably > emulate a SCSI controller in qemu -and- pass-through the SCSI commands > to the host /dev/sg or equivalent (only full device emulation is > reliable). > > This is also typically what something like virtio-scsi allows us to fix, > so let's fix it. IE. we have the ability to query the "limits" of the > real HBA / transport on the host side and to pass them along to the > guest, which enables us to do real pass-through. You can fix this in QEMU; READ and WRITE commands can be split in multiple parts. The scsi-block device I added recently does this. However, it seems like a simple change, so I'll do it. I'll add max_sectors and cmd_per_lun to the config space. Paolo