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Re: [Qemu-devel] core dump with drive-mirror
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] core dump with drive-mirror |
Date: |
Mon, 30 Jun 2014 17:40:16 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
On 06/30/2014 05:16 PM, Eric Blake wrote:
> I'm trying to track down a core dump with the QMP drive-mirror command.
Looks like the bug is related to a base image that is not a multiple of
a cluster size.
>
> # in one terminal:
> cd /tmp
> rm -f base.img snap1.img snap2.img copy.img
>
> # base.img <- snap1.img <- snap2.img; intentionally populating base.img
> # with a qcow2 header, but treating it as raw data
> qemu-img create -f qcow2 base.img 10M
If, right here, I inject:
truncate --size 262144 base.img
> qemu-img create -f qcow2 -b base.img -o backing_fmt=raw snap1.img
> qemu-img create -f qcow2 -b snap1.img -o backing_fmt=qcow2 snap2.img
> cp base.img copy.img
> # Yes, this command line is derived from libvirt...
> LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin \
> QEMU_AUDIO_DRV=none gdb --args /usr/bin/qemu-system-x86_64 \
...then everything else succeeds. So it seems the problem is that qemu
is doing a lousy job of handling a backing file and/or destination file
that is not fully rounded out to a proper size.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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