On 2017-11-15 21:06, Gandalf Corvotempesta wrote:> 2017-11-15 20:59 GMT+01:00 Max Reitz <mreitz@redhat.com>: >> Well, you can't just add support to qemu-img alone either. Every image >> format supported by qemu-img is one supported by qemu as a whole and >> thus needs a proper block driver that needs to support random accesses >> as well. > > I was talking about qemu-img convert, just to convert an XVA image to > something different, in a single pass, without having to extract the > tar.I know, but that doesn't work. qemu-img convert uses the normal general-purpose block drivers for that. Max
Richard W.M. Jones
2017-Nov-15 20:24 UTC
Re: [Libguestfs] [Qemu-devel] [qemu-img] support for XVA
On Wed, Nov 15, 2017 at 09:07:12PM +0100, Max Reitz wrote:> On 2017-11-15 21:06, Gandalf Corvotempesta wrote: > > 2017-11-15 20:59 GMT+01:00 Max Reitz <mreitz@redhat.com>: > >> Well, you can't just add support to qemu-img alone either. Every image > >> format supported by qemu-img is one supported by qemu as a whole and > >> thus needs a proper block driver that needs to support random accesses > >> as well. > > > > I was talking about qemu-img convert, just to convert an XVA image to > > something different, in a single pass, without having to extract the > > tar. > > I know, but that doesn't work. qemu-img convert uses the normal > general-purpose block drivers for that.In any case there's no need as qemu/qemu-img can already access files inside an uncompressed tarball using the offset/size support added to the raw driver exactly for this purpose: https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg03945.html Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v
On 2017-11-15 21:24, Richard W.M. Jones wrote:> On Wed, Nov 15, 2017 at 09:07:12PM +0100, Max Reitz wrote: >> On 2017-11-15 21:06, Gandalf Corvotempesta wrote: >>> 2017-11-15 20:59 GMT+01:00 Max Reitz <mreitz@redhat.com>: >>>> Well, you can't just add support to qemu-img alone either. Every image >>>> format supported by qemu-img is one supported by qemu as a whole and >>>> thus needs a proper block driver that needs to support random accesses >>>> as well. >>> >>> I was talking about qemu-img convert, just to convert an XVA image to >>> something different, in a single pass, without having to extract the >>> tar. >> >> I know, but that doesn't work. qemu-img convert uses the normal >> general-purpose block drivers for that. > > In any case there's no need as qemu/qemu-img can already access files > inside an uncompressed tarball using the offset/size support added to > the raw driver exactly for this purpose: > > https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg03945.htmlIf that works, yes. To me it doesn't look like XVA is just a single raw image inside of a tarball, but I may very well be wrong, of course. Max