Re: [Qemu-devel] [PATCH v5 0/5] Geometry and blocksize detection for backing devices.

[Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>]

On 01/02/2015 02:30 PM, Stefan Hajnoczi wrote:
> On Thu, Dec 18, 2014 at 12:17:59PM +0100, Ekaterina Tumanova wrote:
>> Updates v4 -> v5:
>>
>> Minor Updates according the last review from Markus:
>> 1. update commit message for patch 2
>> 2. fix comment typos
>> 3. fix check_for_dasd to return -1 instead of -ENOTSUP
>>
>> Thanks,
>> Kate.
>>
>> ---------------------------------------------------------------
>>     Patchset Description (didn't change):
>>
>> Proper geometry and blocksize information is vital for support of
>> DASD/ECKD drives in Linux guests. Otherwise things will fail in
>> certain cases.
>>
>> The existing geometry and blocksize qemu defaults have no sense
>> for DASD drives (hd_geometry_guess detection and 512 for sizes).
>> Setting this information manually in XML file is far from user-friendly,
>> as the admin has to manually look up the properties of the
>> host disks and then modify the guest definition accordingly.
>
> What is the expected behavior when you dd the disk image from the DASD
> to a raw image file on an NFS file system on the host?
>
> It seems you'd lose the geometry detection and the disk image could be
> unusable from inside the guest.
>

This patch set doesn't change the handling of the images, dd'ed from
DASDs. Please refer to Christian's reply for details.

Thanks a lot for you review!

Kate.