Re: [Qemu-devel] [Bug 826363] Re: qemu-img convert does not work with vdi files

[Stefan Hajnoczi]

On Mon, Aug 15, 2011 at 11:59 PM, Steve Si <address@hidden> wrote:
> Please see
> http://virtuallyfun.superglobalmegacorp.com/?p=1214#comment-967
>
> confirmed bug replicated by neozeed. Seems to be something to do with vdi's 
> that contain 3-4GB of data.
> An unpartitioned freshly created 4Gb vdi can be converted to raw OK, but an 
> 8Gb dynamic vdi with 3.8GB of data fails.
> Presumably the raw file has sparse data in?? If it has 3+GB of real data then 
> 0.15.0 errors but 0.11.1 does not??

I created a 5 GB vdi file.  Inside it I created an ext4 file system
and a single 4 GB file with random data on that filesystem.

$ ./qemu-img info test.vdi
image: test.vdi
file format: vdi
virtual size: 5.0G (5368709120 bytes)
disk size: 4.2G
cluster_size: 1048576

The image was converted without error on qemu.git/master running on
Linux amd64.  So unfortunately I have not been able to reproduce this.

You could track down the commit which broke this using git-bisect(1).
I recommend first testing QEMU 0.14.0 to see if the bug is present
there.

The steps are:

$ git bisect start master v0.14.0  # broken on master, working on v0.14.0

Then:

$ ./configure [...] && make && qemu-img.exe [...] # check whether it errors

If qemu-img.exe completes successfully:
$ git bisect good
otherwise:
$ git bisect bad

Keep repeating this and you should end up at the commit that
introduced the bug.  If you post that it should be relatively easy to
figure out what the cause of the bug is.

Stefan