On 10/11/2010 11:18 AM, Anthony Liguori wrote:
On 10/11/2010 10:46 AM, Stefan Hajnoczi wrote:
On Mon, Oct 11, 2010 at 05:39:01PM +0200, Avi Kivity wrote:
On 10/11/2010 05:30 PM, Stefan Hajnoczi wrote:
It was discussed before, but I don't think we came to a
conclusion. Are
there any circumstances under which you don't want to set the
QED_CF_BACKING_FORMAT flag?
I suggest the following:
QED_CF_BACKING_FORMAT_RAW = 0x1
When set, the backing file is a raw image and should not be probed for
its file format. The default (unset) means that the backing image
file
format may be probed.
Now the backing_fmt_{offset,size} are no longer necessary.
Should it not be an incompatible option? If the backing disk starts
with a format magic, it will be probed by an older qemu,
incorrectly.
Agreed, it should be a non-compat feature bit.
If it's just raw or not raw, then I agree it should be non-compat.
I think we just need a feature bit then that indicates that the
backing file is non-probeable which certainly simplifies the
implementation.
QED_F_BACKING_FORMAT_NOPROBE maybe?
Er, thinking more, this is still a good idea but we still need
QED_CF_BACKING_FORMAT because we specifically need to know when a
protocol is specified. Otherwise, we have no way of doing nbd as a
backing file.
Regards,
Anthony Liguori
Regards,
Anthony Liguori
Stefan
