Re: [libvirt-users] blockcopy for libvirt and version compatibility

On 12/20/2013 11:45 AM, Mark Trinh wrote: > I'm currently running: > virsh --version > 1.0.2 > > libvirtd --version > libvirtd (libvirt) 1.0.2 > > I have a couple questions. > > 1. Can I upgrade my libvirt.so version to use with an older libvirtd? In > other words, does the versions of libvirt and libvirtd need to be in lock > step? No, they do not have to be in lockstep. libvirt.so communicates to a local libvirtd the same way it communicates to a remote machine, and we took great care in the design to ensure that things error out nicely if the libvirt.so client is newer than the remote server; conversely, if the client is older, the changes have always been back-compat so that a newer server will always talk to the client correctly (although the client being older means that you can't take full advantage of the server). > > > 2. I'm able to use virsh blockcopy, but I want to do it programmatically > via C. I looked through the API and was not able to see any references to > that. I did see mention of virDomainBlockCopy on the TIP of the git > repository, but no other references to it. The source code to virsh shows the APIs that we used; this is a good starting point for any other C binding, and also for any other language binding if you can map the C bindings over to your language bindings. In particular, tools/virsh-domain.c:cmdBlockCopy() is currently implemented atop the virDomainBlockRebase() API call with the VIR_DOMAIN_BLOCK_REBASE_COPY flag (but the door is open to also implement it atop a newer more-powerful virDomainBlockCopy() once we start targetting some of qemu 1.7 or 2.0's newer features). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org