Hi,

>>  1. Always enter Closed state, and then run a cleanup phase in the kexec
>> code which iterates over xenstore device directories, switching
>> Closed->Initialising.

> I'll try (1).  I don't expect it being that hard, I expect doing that in
> the old kernel _after_ unregistering the watches should work just fine.

Here we go, changes:

 * new helper function xenbus_strstate() for more readable debug output.
 * some of the DPRINK()'s got some more info to print added (device
   node, state on state changes).
 * Both sides will happily enter "Closed" state without deleting the
   device.
 * There is a new helper function xenbus_reinit_frontend_devices() for
   kexec:  It unregisteres the watch (to prevent the device from being
   reinitialized in the old kernel) and moves devices from Closed back
   to Initialising state.

cheers,

  Gerd

-- 
Gerd Hoffmann <kraxel@suse.de>
http://www.suse.de/~kraxel/julika-dora.jpeg