[Engine-devel] unmanaged devices thrown into 'custom' feature

[Livnat Peer]

On 21/10/12 16:42, Dan Kenigsberg wrote:
> I have just noticed that when a VM is started for the second time, Engine
> issues the "create" vdsm verb with some information regarding
> "unmanaged" devices (an example is shown below[1]) in the 'custom'
> propery bag.
> 
> I'm surprised about this, as I was not aware of this usage of the
> 'custom' dictionary, and Vdsm is not doing anything with the data.
> 

If I recall correctly the idea of passing the unmanaged devices data in
the custom property was to enable managing stable device addresses in
the hooks (to devices that were added to the VM via hooks from the first
place), so this info is there not for VDSM use.
For example if you add a device in a hook it will be kept in the engine
as a non managed device. later when starting the VM again you would like
to assign the same device address to your device, and you can do so
because you have access to the original address in the custom properties
of the VM.



> Would anyone elaborate about it? On the face of it, it does not seem
> like a pleasant API. If Engine wants to tell Vdsm about the location of
> various devices, we should probably be using the 'devices' property, not
> the bag of 'custom' property made for user-defined hooks.
> 
> I hope this API pecularity can be avoided, and very much hope that no
> one is depending on it.
> 
> Dan.
> 
> 
> [1]
> 'custom': {
>     'device_e97a9759-1c1b-45ed-9ed9-7136ef538315': 'VmDevice {vmId=068d4914-4191-400d-a220-17a7f2d8e80c, deviceId=e97a9759-1c1b-45ed-9ed9-7136ef538315, device=ide, type=controller, bootOrder=0, specParams={}, address={bus=0x00, domain=0x0000, type=pci, slot=0x01, function=0x1}, managed=false, plugged=true, readOnly=false, alias=ide0}',
>     'device_e97a9759-1c1b-45ed-9ed9-7136ef538315device_133d9bfa-c531-414e-ad20-208d67d5a5e6device_7bfffa34-2e27-4b01-b499-6ac79c997709': 'VmDevice {vmId=068d4914-4191-400d-a220-17a7f2d8e80c, deviceId=7bfffa34-2e27-4b01-b499-6ac79c997709, device=unix, type=channel, bootOrder=0, specParams={}, address={port=1, bus=0, controller=0, type=virtio-serial}, managed=false, plugged=true, readOnly=false, alias=channel0}',
>     'device_e97a9759-1c1b-45ed-9ed9-7136ef538315device_133d9bfa-c531-414e-ad20-208d67d5a5e6': 'VmDevice {vmId=068d4914-4191-400d-a220-17a7f2d8e80c, deviceId=133d9bfa-c531-414e-ad20-208d67d5a5e6, device=virtio-serial, type=controller, bootOrder=0, specParams={}, address={bus=0x00, domain=0x0000, type=pci, slot=0x04, function=0x0}, managed=false, plugged=true, readOnly=false, alias=virtio-serial0}',
>     'device_e97a9759-1c1b-45ed-9ed9-7136ef538315device_133d9bfa-c531-414e-ad20-208d67d5a5e6device_7bfffa34-2e27-4b01-b499-6ac79c997709device_7c107c63-605f-4b21-9893-c052ec211424device_48007de9-467d-46a1-aa84-cc1a6419b5fb': 'VmDevice {vmId=068d4914-4191-400d-a220-17a7f2d8e80c, deviceId=48007de9-467d-46a1-aa84-cc1a6419b5fb, device=spicevmc, type=channel, bootOrder=0, specParams={}, address={port=3, bus=0, controller=0, type=virtio-serial}, managed=false, plugged=true, readOnly=false, alias=channel2}',
>     'device_e97a9759-1c1b-45ed-9ed9-7136ef538315device_133d9bfa-c531-414e-ad20-208d67d5a5e6device_7bfffa34-2e27-4b01-b499-6ac79c997709device_7c107c63-605f-4b21-9893-c052ec211424': 'VmDevice {vmId=068d4914-4191-400d-a220-17a7f2d8e80c, deviceId=7c107c63-605f-4b21-9893-c052ec211424, device=unix, type=channel, bootOrder=0, specParams={}, address={port=2, bus=0, controller=0, type=virtio-serial}, managed=false, plugged=true, readOnly=false, alias=channel1}'
> }
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