Re: [Qemu-devel] [PATCH v1 1/3] qdev: Expose the qdev id string as a prop

[Paolo Bonzini]

Il 16/04/2014 19:20, Andreas Färber ha scritto:
> qdev paths used for VMState currently still depend on a bus, which Alex
> or Alexey wanted to look into fixing. By default -1 is supplied by
> DeviceState for registering dc->vmsd, which can be overridden by
> inlining the corresponding qdev.c code or more conveniently - Alex'
> suggestion yesterday - by moving that default value of -1 into an
> overrideable instance field.

Or even better, do not use the instance_id.  It is prone to break when 
you have hotplug (because instance_ids on the source and destination 
might be different).  instance_ids work for sysbus, but for everything 
else they'd better be avoided.

In order to migrate hotpluggable busless devices, we will need an 
alternative, device-based implementation of qdev_get_dev_path.

DIMM will be the first example of a hotpluggable busless device, but I 
think it is stateless so the problem will not be there.

Paolo