From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support Date: Wed, 29 Apr 2009 13:07:32 +0200 Message-ID: <200904291307.33523.borntraeger@de.ibm.com> References: <20090427082606.GA32604@lst.de> <200904282109.52905.borntraeger@de.ibm.com> <20090429105004.GB7846@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Hannes Reinecke , Rusty Russell , qemu-devel@nongnu.org, kvm@vger.kernel.org To: Christoph Hellwig Return-path: Received: from mtagate8.de.ibm.com ([195.212.29.157]:56091 "EHLO mtagate8.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760296AbZD2LI0 (ORCPT ); Wed, 29 Apr 2009 07:08:26 -0400 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate8.de.ibm.com (8.14.3/8.13.8) with ESMTP id n3TB7Z6L177904 for ; Wed, 29 Apr 2009 11:07:35 GMT Received: from d12av04.megacenter.de.ibm.com (d12av04.megacenter.de.ibm.com [9.149.165.229]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3TB7YB04325388 for ; Wed, 29 Apr 2009 13:07:34 +0200 Received: from d12av04.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av04.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3TB7XAH001751 for ; Wed, 29 Apr 2009 13:07:34 +0200 In-Reply-To: <20090429105004.GB7846@lst.de> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: Am Wednesday 29 April 2009 12:50:04 schrieb Christoph Hellwig: > On Tue, Apr 28, 2009 at 09:09:52PM +0200, Christian Borntraeger wrote: > > Yes, virtio-scsi is also something we were thinking of. The last time we discussed this idea of SCSI passthrough internally, we stumbled over error recovery. Who is responsible for the error recovery? The host, the guest, or both? Are there problems, which will trigger error recovery in the guest and host midlayer at the same time? To be honest, my scsi knowledge is very limited, so I dont know if that is a real problem. > > I'm not that far with planning yet. The best way would be to do real > error handling in the host probably. Yes, that was my impression too. The tricky part is the timeout based recovery found in the scsi midlayer (e.g. scsi-error.c). In case of a timeout the guest and the host will start recovery at the same time. Christian From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Lz7e6-0000eC-2x for qemu-devel@nongnu.org; Wed, 29 Apr 2009 07:08:10 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Lz7e1-0000d8-Ak for qemu-devel@nongnu.org; Wed, 29 Apr 2009 07:08:09 -0400 Received: from [199.232.76.173] (port=35958 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Lz7e1-0000d5-6h for qemu-devel@nongnu.org; Wed, 29 Apr 2009 07:08:05 -0400 Received: from mtagate7.de.ibm.com ([195.212.29.156]:37822) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Lz7e0-0005qv-Fm for qemu-devel@nongnu.org; Wed, 29 Apr 2009 07:08:04 -0400 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate7.de.ibm.com (8.14.3/8.13.8) with ESMTP id n3TB7YKH168400 for ; Wed, 29 Apr 2009 11:07:34 GMT Received: from d12av04.megacenter.de.ibm.com (d12av04.megacenter.de.ibm.com [9.149.165.229]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3TB7YsS2781428 for ; Wed, 29 Apr 2009 13:07:34 +0200 Received: from d12av04.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av04.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3TB7XAB001751 for ; Wed, 29 Apr 2009 13:07:34 +0200 From: Christian Borntraeger Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support Date: Wed, 29 Apr 2009 13:07:32 +0200 References: <20090427082606.GA32604@lst.de> <200904282109.52905.borntraeger@de.ibm.com> <20090429105004.GB7846@lst.de> In-Reply-To: <20090429105004.GB7846@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904291307.33523.borntraeger@de.ibm.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: Rusty Russell , Hannes Reinecke , kvm@vger.kernel.org, qemu-devel@nongnu.org Am Wednesday 29 April 2009 12:50:04 schrieb Christoph Hellwig: > On Tue, Apr 28, 2009 at 09:09:52PM +0200, Christian Borntraeger wrote: > > Yes, virtio-scsi is also something we were thinking of. The last time we discussed this idea of SCSI passthrough internally, we stumbled over error recovery. Who is responsible for the error recovery? The host, the guest, or both? Are there problems, which will trigger error recovery in the guest and host midlayer at the same time? To be honest, my scsi knowledge is very limited, so I dont know if that is a real problem. > > I'm not that far with planning yet. The best way would be to do real > error handling in the host probably. Yes, that was my impression too. The tricky part is the timeout based recovery found in the scsi midlayer (e.g. scsi-error.c). In case of a timeout the guest and the host will start recovery at the same time. Christian