Re: [libvirt] [Qemu-devel] live snapshot wiki updated

["Daniel P. Berrange" <berrange redhat com>]

On Tue, Jul 19, 2011 at 04:30:19PM +0200, Jes Sorensen wrote:
> On 07/19/11 16:24, Eric Blake wrote:
> > [adding the libvir-list]
> > On 07/19/2011 08:09 AM, Jes Sorensen wrote:
> >> Urgh, libvirt parsing image files is really unfortunate, it really
> >> doesn't give me warm fuzzy feelings :( libvirt really should not know
> >> about internals of image formats.
> > 
> > But even if you add new features to qemu to avoid needing this in the
> > future, it doesn't change the past - libvirt will always have to know
> > how to parse image files understood by older qemu, and so as long as
> > libvirt already knows how to do that parsing, we might as well take
> > advantage of it.
> 
> What has been done here in the past is plain wrong. Continuing to do it
> isn't the right thing to do here.
> 
> > Besides, I feel that having a well-documented file format, so that
> > independent applications can both parse the same file with the same
> > semantics by obeying the file format specification, is a good design goal.
> 
> We all know that documentation is rarely uptodate, new features may not
> get added and libvirt will never be able to keep up. The driver for a
> file format belongs in QEMU and nowhere else.

This would be possible if QEMU to provide a libblockformat.so library
which allowed apps to extract metadata from file formats using a stable
API.

Daniel
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