hi, Cyborg and nova team:
I am using cyborg with "Wallaby" release to manage my accelerator devices, while I'm trying to unbind the accelerator I found that the device was not actually unbound from the virtual machine. 
Here are my questions:
1. What is the function of the arq unbind command in cyborg ?
2. How to unbind the accelerator which bounded to vm? Does nova or cyborg support this function now?

Here are my steps:
step1: openstack accelerator arq unbind ed205084-f58d-4fad-99b4-327a1398858f
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| uuid                | ed205084-f58d-4fad-99b4-327a1398858f |
| state               | Unbound                              |
| device_profile_name | ssd                                  |
| hostname            | None                                 |
| device_rp_uuid      | None                                 |
| instance_uuid       | None                                 |
| attach_handle_type  |                                      |
| attach_handle_info  | {}                                   |
+---------------------+--------------------------------------+
 step2: login vm and check the device, but it still here.
step3: stop vm and start vm, met the following error:
"nova.exception.AcceleratorRequestOpFailed: Failed to get accelerator requests: Cyborg returned no accelerator requests for instance ca77ef4e-421c-4c6c-9d76-7618a90ec921"