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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>,
	Rusty Russell <rusty@rustcorp.com.au>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support
Date: Wed, 29 Apr 2009 13:07:32 +0200	[thread overview]
Message-ID: <200904291307.33523.borntraeger@de.ibm.com> (raw)
In-Reply-To: <20090429105004.GB7846@lst.de>

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

WARNING: multiple messages have this Message-ID (diff)
From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
	Hannes Reinecke <hare@suse.de>,
	kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support
Date: Wed, 29 Apr 2009 13:07:32 +0200	[thread overview]
Message-ID: <200904291307.33523.borntraeger@de.ibm.com> (raw)
In-Reply-To: <20090429105004.GB7846@lst.de>

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

  reply	other threads:[~2009-04-29 11:08 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-27  8:26 [PATCH] virtio-blk: add SGI_IO passthru support Christoph Hellwig
2009-04-27  8:29 ` Christoph Hellwig
2009-04-27  8:29   ` [Qemu-devel] " Christoph Hellwig
2009-04-27  9:15   ` Avi Kivity
2009-04-27  9:15     ` [Qemu-devel] " Avi Kivity
2009-04-28  9:47     ` Christoph Hellwig
2009-04-28  9:47       ` Christoph Hellwig
2009-04-27 14:36   ` Anthony Liguori
2009-04-27 14:36     ` [Qemu-devel] " Anthony Liguori
2009-04-28  9:51     ` Christoph Hellwig
2009-04-28  9:51       ` Christoph Hellwig
2009-04-28 16:37       ` Anthony Liguori
2009-04-28 16:52         ` Christian Borntraeger
2009-04-28 16:52           ` Christian Borntraeger
2009-04-29 10:48         ` Christoph Hellwig
2009-04-29 10:48           ` Christoph Hellwig
2009-04-29 11:11           ` Paul Brook
2009-04-29 11:11             ` Paul Brook
2009-04-29 11:19             ` Christian Borntraeger
2009-04-29 11:19               ` Christian Borntraeger
2009-04-29 11:29               ` Paul Brook
2009-04-29 11:29                 ` Paul Brook
2009-04-29 11:21             ` Christoph Hellwig
2009-04-29 11:21               ` Christoph Hellwig
2009-04-29 11:37               ` Paul Brook
2009-04-29 11:37                 ` Paul Brook
2009-04-30 20:13                 ` Christoph Hellwig
2009-04-30 20:13                   ` Christoph Hellwig
2009-04-30 20:55                   ` Nicholas A. Bellinger
2009-04-30 20:55                     ` Nicholas A. Bellinger
2009-04-30 21:49                   ` Paul Brook
2009-04-30 21:49                     ` Paul Brook
2009-04-30 21:56                     ` Javier Guerra
2009-04-30 21:56                       ` Javier Guerra
2009-05-01  7:24                     ` Christoph Hellwig
2009-05-01  7:24                       ` Christoph Hellwig
2009-05-01 11:08                       ` Jamie Lokier
2009-05-01 11:08                         ` Jamie Lokier
2009-05-01 14:28                         ` Christoph Hellwig
2009-05-01 14:28                           ` Christoph Hellwig
2009-05-05  5:21                   ` Rusty Russell
2009-05-05  5:21                     ` Rusty Russell
2009-04-28 19:09       ` Christian Borntraeger
2009-04-28 19:09         ` Christian Borntraeger
2009-04-29 10:50         ` Christoph Hellwig
2009-04-29 10:50           ` Christoph Hellwig
2009-04-29 11:07           ` Christian Borntraeger [this message]
2009-04-29 11:07             ` Christian Borntraeger
2009-04-28  9:57   ` [PATCH 2/2] virtio-blk: add SG_IO " Christoph Hellwig
2009-04-28  9:57     ` [Qemu-devel] " Christoph Hellwig

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