libvirt users - Jul 2011 - virt-manager/libvirt backwards compatibility problem?

Hi,

Wanting to test some recent features of libvirt, I installed 0.9.3 on a
couple of systems. It works fine on those, but since upgrading neither of
them can successfully connect with virt-manager or virsh to a couple of
other systems running libvirt 0.8.3. Even after upgrading virt-manager and
virtinst to the latest versions on the 0.9.3 systems, they fail like this
in virt-manager:

  Unable to open a connection to the libvirt management daemon.

  Libvirt URI is: qemu+ssh://root at 192.168.1.67/system

  Verify that:
   - The 'libvirtd' daemon has been started

  Cannot recv data: : Connection reset by peer

  Traceback (most recent call last):
    File "/usr/src/virt-manager-0.8.7/src/virtManager/connection.py",
line
  1055, in _try_open
      None], flags)
    File "/usr/local/lib/python2.7/dist-packages/libvirt.py", line
102, in
  openAuth
      if ret is None:raise libvirtError('virConnectOpenAuth() failed')
  libvirtError: Cannot recv data: : Connection reset by peer

Virsh simple fails with:

  error: Cannot recv data: : Connection reset by peer
  error: failed to connect to the hypervisor

Since it's certain that the libvirtd daemon has been started on the other
systems (they have production VMs that are running), this leaves me puzzled.
This connection for virt-manager worked flawlessly for months when all the
systems had libvirt 0.8.3.

Is this a known incompatibility? Something I have to tweak somewhere?

Thanks,
Whit

Interestingly, drbd-mc 0.9.4 still works fine (in a virt-manager-like way)
from the systems with the updated libvirt to the systems with the older
version. So the problem looks to be with libvirt 0.9.3 in some way, when
called by virt-manager or virst to connect to an older libvirt-based system.

Whit

> This connection for virt-manager worked flawlessly for months when all the
> systems had libvirt 0.8.3.
> 
> Is this a known incompatibility? Something I have to tweak somewhere?
Reverting to 0.8.8 for libvirtd - and virt-manager 0.8.6 - works connecting
to the 0.8.3 systems. 

Dropping to 0.9.2 didn't. 

Is this by design that, say, 0.9.x isn't backwards-compatible in terms of
using virt-manager on it to manage 0.8.x systems? Or is it a bug I should
file somewhere?

Thanks,
Whit