From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 3/3] megasas: LSI Megaraid SAS emulation Date: Sun, 03 Jul 2011 16:36:22 +0200 Message-ID: <4E107E66.3030001@redhat.com> References: <1309534555-22178-1-git-send-email-hare@suse.de> <1309534555-22178-2-git-send-email-hare@suse.de> <1309534555-22178-3-git-send-email-hare@suse.de> <1309534555-22178-4-git-send-email-hare@suse.de> <4E0F2215.4040307@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org To: kvm@vger.kernel.org Return-path: Received: from lo.gmane.org ([80.91.229.12]:57678 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755183Ab1GCOgg (ORCPT ); Sun, 3 Jul 2011 10:36:36 -0400 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1QdNmk-00068b-Gu for kvm@vger.kernel.org; Sun, 03 Jul 2011 16:36:34 +0200 Received: from 93-34-199-31.ip51.fastwebnet.it ([93.34.199.31]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 03 Jul 2011 16:36:34 +0200 Received: from pbonzini by 93-34-199-31.ip51.fastwebnet.it with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 03 Jul 2011 16:36:34 +0200 In-Reply-To: <4E0F2215.4040307@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: On 07/02/2011 03:50 PM, Hannes Reinecke wrote: > (And no, I will not getting into another dog-fight with Paul B. here. > Virtio can do without bounce buffers. AHCI can. So I fail to see why > SCSI has to rely on bounce buffers.) I agree, but I do see why a SCSI device might prefer to rely on bounce buffers for non-I/O commands. This is why in my last RFC series for vmw_pvscsi I let the device choose whether to force a bounce buffer or get an external iovec from the HBA. Paolo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41694) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QdNmf-0007JR-Cy for qemu-devel@nongnu.org; Sun, 03 Jul 2011 10:36:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QdNmd-0008Ln-Ul for qemu-devel@nongnu.org; Sun, 03 Jul 2011 10:36:29 -0400 Received: from mail-wy0-f173.google.com ([74.125.82.173]:46964) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QdNmd-0008LB-Jl for qemu-devel@nongnu.org; Sun, 03 Jul 2011 10:36:27 -0400 Received: by wyf28 with SMTP id 28so3443840wyf.4 for ; Sun, 03 Jul 2011 07:36:26 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <4E107E66.3030001@redhat.com> Date: Sun, 03 Jul 2011 16:36:22 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1309534555-22178-1-git-send-email-hare@suse.de> <1309534555-22178-2-git-send-email-hare@suse.de> <1309534555-22178-3-git-send-email-hare@suse.de> <1309534555-22178-4-git-send-email-hare@suse.de> <4E0F2215.4040307@suse.de> In-Reply-To: <4E0F2215.4040307@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/3] megasas: LSI Megaraid SAS emulation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hannes Reinecke Cc: kvm@vger.kernel.org, Alexander Graf , Stefan Haynoczi , qemu-devel@nongnu.org On 07/02/2011 03:50 PM, Hannes Reinecke wrote: > (And no, I will not getting into another dog-fight with Paul B. here. > Virtio can do without bounce buffers. AHCI can. So I fail to see why > SCSI has to rely on bounce buffers.) I agree, but I do see why a SCSI device might prefer to rely on bounce buffers for non-I/O commands. This is why in my last RFC series for vmw_pvscsi I let the device choose whether to force a bounce buffer or get an external iovec from the HBA. Paolo