Re: Storing command line options in qcow2 images

Jorge Lucángeli Obes
2007-08-08T18:21:40Z

On 8/8/07, Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> wrote:
> Avi Kivity wrote:
> > Anthony Liguori wrote:
> >
> >> I don't think adding annotations as snapshots is the right approach. I
> >> think proper support should be added in the header. I wouldn't be too
> >> concerned with breaking compatibility in qcow2. That's why it's qcow2
> >> and not just an updated version of qcow, qcow2 is still, AFAIK, open for
> >> breakage.
> >>
> >>
> >
> > Are all the users' images open for breakage too?
> >
>
> FWIW, you can extended the header without causing a breakage. Just bump
> the version, add the field, and add appropriate code. Of course, this
> is technically qcow v3 but it's a good opportunity to make things a bit
> sanier such that instead of check version == QCOW_VERSION that version
> >= QCOW_VERSION.

I think that for now we can try the snapshot-based approach, as it is
the least intrusive one. I wouldn't push for a format change just with
this minor feature. However, I would be glad to convert our code if
the general consensus was that we need a new format.

Patches for our solution follow. They are against:

5b16d32e3785274310e9e1970f4221b4966c5474

Which was userspace a few minutes ago.

Cheers,
Jorge