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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 19 Jun 2012 20:42:57 +1000
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Subject: Re: [Qemu-devel] [Bug 1013241] Re: qemu-system-ppc64 hanging
 occasionally in disk	writes
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To: Bug 1013241 <1013241@bugs.launchpad.net>
Cc: qemu-devel@nongnu.org

On Tue, 2012-06-19 at 10:16 +0000, Richard W.M. Jones wrote:
> I switched to using virtio-scsi (instead of virtio-blk).  This appears to have solved
> this problem, although it brings another problem.  I also tried vscsi, which fixes
> both problems.
> 
> Therefore I will (not definitively) claim that the problem lies somewhere in virtio-blk,
> but a workaround seems to be available.

What was the virtio-scsi problem ? (Other than SLOF doesn't know about
it yet :-) I haven't audited/tested it so it might have endian issues...

I have reproduced a similar hang with vscsi in full emulation, I haven't
observed your problem with virtio-blk, I plan to spend more time doing
some torture testing & debugging this week see if I can find out what's
going on.

BTW. What was your guest kernel version ?

Cheers,
Ben.