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Re: [Xen-devel] Re: Reuse QEMU image for HVM?

To: "Jun Koi" <junkoi2004@xxxxxxxxx>
Subject: Re: [Xen-devel] Re: Reuse QEMU image for HVM?
From: "Grant McWilliams" <grantmasterflash@xxxxxxxxx>
Date: Tue, 9 Dec 2008 00:29:28 -0800
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
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On Mon, Dec 8, 2008 at 7:50 PM, Jun Koi <junkoi2004@xxxxxxxxx> wrote:
On Tue, Dec 9, 2008 at 1:34 AM, Grant McWilliams
<grantmasterflash@xxxxxxxxx> wrote:
>>
>>
>> It seems that the reason is qcow2 file created by QEMU tool is not
>> supported by Xen??
>>
>> Thanks,
>> Jun
>>
>> _______________________________________________
>
> From what I know this is true. It is probably the biggest blunder of the
> virtualization world! I'd like to
> know who at the xen team decided to adopt qcow but not make it compatible
> with QEMU. You can
> use qcow but you need to use xen's tool to create it. From what I understand
> there's a difference in
> endianness of the file.

Too sad if that is true. Could anybody confirm this?

I tried to see if that is true or not, by creating 2 images with
qemu-img (from QEMU) and qemu-img-xen (from Xen). The command is like
below:

qemu-img create -f qcow2 img.test1 10MB
qemu-img-xen create -f qcow2 img.test2 10MB

And then I tried to diff these 2 files (diff img.test1 img.test2), but
the result was: 2 files are completely same.

So it doesnt seem right that qemu-img-xen does something difference
with qcow2 format. I tried to compare qcow format, too, and didnt see
any difference.

Any idea??
Jun



I googled it and the source I got it from said to use only qcow-create and img2qcow utilities and not to use qemu-img because of the incompatibilities. Later I saw posts on this mailing list outlining the endian difference between qemu qcow and xen qcow.

Here's a thread that I followed, it's as new as March 08...http://lists.xensource.com/archives/html/xen-devel/2008-03/msg00728.html


Grant McWilliams
 

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