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

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