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.

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}' } _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel

From: "Yair Zaslavsky" <yzaslavs(a)redhat.com&gt; To: "Livnat Peer" <lpeer(a)redhat.com&gt; Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org Sent: Sunday, October 21, 2012 5:38:54 PM Subject: Re: [Engine-devel] unmanaged devices thrown into 'custom' feature ----- Original Message ----- > From: "Livnat Peer" <lpeer(a)redhat.com&gt; > To: "Dan Kenigsberg" <danken(a)redhat.com&gt; > Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, > engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org > Sent: Sunday, October 21, 2012 5:18:31 PM > Subject: Re: [Engine-devel] unmanaged devices thrown into 'custom' > feature > > 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. This is exactly what Eli has explained Gendai and Dan today.

However, just to elaborate - these "extra properties" are not stored at the two columns of vm_static (userdefined_properties, predefined_properties) at the DB. > > > > > 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}' > > } > > _______________________________________________ > > Engine-devel mailing list > > Engine-devel(a)ovirt.org > > http://lists.ovirt.org/mailman/listinfo/engine-devel > > > > _______________________________________________ > Engine-devel mailing list > Engine-devel(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/engine-devel > _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel

On Sun, Oct 21, 2012 at 11:57:10AM -0400, Eli Mesika wrote: > > > ----- Original Message ----- >> From: "Yair Zaslavsky" <yzaslavs(a)redhat.com&gt; >> To: "Livnat Peer" <lpeer(a)redhat.com&gt; >> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org >> Sent: Sunday, October 21, 2012 5:38:54 PM >> Subject: Re: [Engine-devel] unmanaged devices thrown into 'custom' feature >> >> >> >> ----- Original Message ----- >>> From: "Livnat Peer" <lpeer(a)redhat.com&gt; >>> To: "Dan Kenigsberg" <danken(a)redhat.com&gt; >>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, >>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org >>> Sent: Sunday, October 21, 2012 5:18:31 PM >>> Subject: Re: [Engine-devel] unmanaged devices thrown into 'custom' >>> feature >>> >>> 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. >> >> This is exactly what Eli has explained Gendai and Dan today. (I was asking here because I did not understand the verbal explanation.) > > This is taken from the Stable Device Address design in > http://wiki.ovirt.org/wiki/Features/Design/StableDeviceAddresses > > Unmanaged Device > ----------------- > Unmanaged Device will be supported in the new format and will include all unhandled devices as sound/controller/etc and future devices. Those devices will be persistent and will have Type , SubType (device specific) and an Address. For 3.1 an unmanaged Device is not exposed to any GUI/REST API. Unmanaged devices are passed to vdsm inside a Custom property. VDSM in it turn is passing this as is for possible hook processing. Thanks for the elaboration. Too bad that I've missed this issue before. Are you aware of any hook making use of this? I hope that hook writers are not using APIs that are not documented in vdsmd(8). It seems as a classic case where a generic bag interface is coerced into an awkward partially-documented interface. I think that a better approach would have been to pass all devices (managed and unmanaged alike) in the 'devices' property, and let vdsm expose whatever is needed to the before_vm_start hook. Maybe we can still do this.

Dan. _______________________________________________ vdsm-devel mailing list vdsm-devel(a)lists.fedorahosted.org https://lists.fedorahosted.org/mailman/listinfo/vdsm-devel

----- Original Message ----- > From: "Livnat Peer" <lpeer(a)redhat.com&gt; > To: "Dan Kenigsberg" <danken(a)redhat.com&gt; > Cc: engine-devel(a)ovirt.org, "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, vdsm-devel(a)fedorahosted.org > Sent: Monday, October 22, 2012 8:29:20 AM > Subject: Re: [Engine-devel] [vdsm] unmanaged devices thrown into 'custom' feature > > On 21/10/12 23:49, Dan Kenigsberg wrote: > > On Sun, Oct 21, 2012 at 11:57:10AM -0400, Eli Mesika wrote: > >> > >> > >> ----- Original Message ----- > >>> From: "Yair Zaslavsky" <yzaslavs(a)redhat.com&gt; > >>> To: "Livnat Peer" <lpeer(a)redhat.com&gt; > >>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, > >>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org > >>> Sent: Sunday, October 21, 2012 5:38:54 PM > >>> Subject: Re: [Engine-devel] unmanaged devices thrown into > >>> 'custom' feature > >>> > >>> > >>> > >>> ----- Original Message ----- > >>>> From: "Livnat Peer" <lpeer(a)redhat.com&gt; > >>>> To: "Dan Kenigsberg" <danken(a)redhat.com&gt; > >>>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, > >>>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org > >>>> Sent: Sunday, October 21, 2012 5:18:31 PM > >>>> Subject: Re: [Engine-devel] unmanaged devices thrown into > >>>> 'custom' > >>>> feature > >>>> > >>>> 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. > >>> > >>> This is exactly what Eli has explained Gendai and Dan today. > > > > (I was asking here because I did not understand the verbal > > explanation.) > > > >> > >> This is taken from the Stable Device Address design in > >> http://wiki.ovirt.org/wiki/Features/Design/StableDeviceAddresses > >> > >> Unmanaged Device > >> ----------------- > >> Unmanaged Device will be supported in the new format and will > >> include all unhandled devices as sound/controller/etc and future > >> devices. Those devices will be persistent and will have Type , > >> SubType (device specific) and an Address. For 3.1 an unmanaged > >> Device is not exposed to any GUI/REST API. Unmanaged devices are > >> passed to vdsm inside a Custom property. VDSM in it turn is > >> passing this as is for possible hook processing. > > > > Thanks for the elaboration. Too bad that I've missed this issue > > before. > > > > Are you aware of any hook making use of this? I hope that hook > > writers > > are not using APIs that are not documented in vdsmd(8). > > > > It seems as a classic case where a generic bag interface is coerced > > into > > an awkward partially-documented interface. > > > > I think that a better approach would have been to pass all devices > > (managed and unmanaged alike) in the 'devices' property, and let > > vdsm > > expose whatever is needed to the before_vm_start hook. > > > > Maybe we can still do this. > > That was the original idea but Ayal objected and I think Igor did not > like it as well... > +2. The original design had an 'unmanaged' (or generic) device type, and all devices should have been normalized. But as explained, this was strongly rejected in the VDSM side, causing Eli write some special handling for this anomaly.

On Tue, Oct 23, 2012 at 05:53:20AM -0400, Doron Fediuck wrote: > > > ----- Original Message ----- > > From: "Livnat Peer" <lpeer(a)redhat.com&gt; > > To: "Dan Kenigsberg" <danken(a)redhat.com&gt; > > Cc: engine-devel(a)ovirt.org, "Genadi Chereshnya" > > <gcheresh(a)redhat.com&gt;, vdsm-devel(a)fedorahosted.org > > Sent: Monday, October 22, 2012 8:29:20 AM > > Subject: Re: [Engine-devel] [vdsm] unmanaged devices thrown into > > 'custom' feature > > > > On 21/10/12 23:49, Dan Kenigsberg wrote: > > > On Sun, Oct 21, 2012 at 11:57:10AM -0400, Eli Mesika wrote: > > >> > > >> > > >> ----- Original Message ----- > > >>> From: "Yair Zaslavsky" <yzaslavs(a)redhat.com&gt; > > >>> To: "Livnat Peer" <lpeer(a)redhat.com&gt; > > >>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, > > >>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org > > >>> Sent: Sunday, October 21, 2012 5:38:54 PM > > >>> Subject: Re: [Engine-devel] unmanaged devices thrown into > > >>> 'custom' feature > > >>> > > >>> > > >>> > > >>> ----- Original Message ----- > > >>>> From: "Livnat Peer" <lpeer(a)redhat.com&gt; > > >>>> To: "Dan Kenigsberg" <danken(a)redhat.com&gt; > > >>>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, > > >>>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org > > >>>> Sent: Sunday, October 21, 2012 5:18:31 PM > > >>>> Subject: Re: [Engine-devel] unmanaged devices thrown into > > >>>> 'custom' > > >>>> feature > > >>>> > > >>>> 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. > > >>> > > >>> This is exactly what Eli has explained Gendai and Dan today. > > > > > > (I was asking here because I did not understand the verbal > > > explanation.) > > > > > >> > > >> This is taken from the Stable Device Address design in > > >> http://wiki.ovirt.org/wiki/Features/Design/StableDeviceAddresses > > >> > > >> Unmanaged Device > > >> ----------------- > > >> Unmanaged Device will be supported in the new format and will > > >> include all unhandled devices as sound/controller/etc and > > >> future > > >> devices. Those devices will be persistent and will have Type , > > >> SubType (device specific) and an Address. For 3.1 an unmanaged > > >> Device is not exposed to any GUI/REST API. Unmanaged devices > > >> are > > >> passed to vdsm inside a Custom property. VDSM in it turn is > > >> passing this as is for possible hook processing. > > > > > > Thanks for the elaboration. Too bad that I've missed this issue > > > before. > > > > > > Are you aware of any hook making use of this? I hope that hook > > > writers > > > are not using APIs that are not documented in vdsmd(8). > > > > > > It seems as a classic case where a generic bag interface is > > > coerced > > > into > > > an awkward partially-documented interface. > > > > > > I think that a better approach would have been to pass all > > > devices > > > (managed and unmanaged alike) in the 'devices' property, and > > > let > > > vdsm > > > expose whatever is needed to the before_vm_start hook. > > > > > > Maybe we can still do this. > > > > That was the original idea but Ayal objected and I think Igor did > > not > > like it as well... > > > > +2. > The original design had an 'unmanaged' (or generic) device type, > and all > devices should have been normalized. But as explained, this was > strongly > rejected in the VDSM side, causing Eli write some special handling > for this anomaly. Can someone (Ayal?) explain the rejection on Vdsm side? Hiding part of the API in the custom propery bag requires strong reasoning indeed.

Dan. _______________________________________________ vdsm-devel mailing list vdsm-devel(a)lists.fedorahosted.org https://lists.fedorahosted.org/mailman/listinfo/vdsm-devel

On 10/23/2012 10:52 PM, Ayal Baron wrote: > > > ----- Original Message ----- >> On Tue, Oct 23, 2012 at 05:53:20AM -0400, Doron Fediuck wrote: >>> >>> >>> ----- Original Message ----- >>>> From: "Livnat Peer" <lpeer(a)redhat.com&gt; >>>> To: "Dan Kenigsberg" <danken(a)redhat.com&gt; >>>> Cc: engine-devel(a)ovirt.org, "Genadi Chereshnya" >>>> <gcheresh(a)redhat.com&gt;, vdsm-devel(a)fedorahosted.org >>>> Sent: Monday, October 22, 2012 8:29:20 AM >>>> Subject: Re: [Engine-devel] [vdsm] unmanaged devices thrown into >>>> 'custom' feature >>>> >>>> On 21/10/12 23:49, Dan Kenigsberg wrote: >>>>> On Sun, Oct 21, 2012 at 11:57:10AM -0400, Eli Mesika wrote: >>>>>> >>>>>> >>>>>> ----- Original Message ----- >>>>>>> From: "Yair Zaslavsky" <yzaslavs(a)redhat.com&gt; >>>>>>> To: "Livnat Peer" <lpeer(a)redhat.com&gt; >>>>>>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, >>>>>>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org >>>>>>> Sent: Sunday, October 21, 2012 5:38:54 PM >>>>>>> Subject: Re: [Engine-devel] unmanaged devices thrown into >>>>>>> 'custom' feature >>>>>>> >>>>>>> >>>>>>> >>>>>>> ----- Original Message ----- >>>>>>>> From: "Livnat Peer" <lpeer(a)redhat.com&gt; >>>>>>>> To: "Dan Kenigsberg" <danken(a)redhat.com&gt; >>>>>>>> Cc: "Genadi Chereshnya" <gcheresh(a)redhat.com&gt;, >>>>>>>> engine-devel(a)ovirt.org, vdsm-devel(a)fedorahosted.org >>>>>>>> Sent: Sunday, October 21, 2012 5:18:31 PM >>>>>>>> Subject: Re: [Engine-devel] unmanaged devices thrown into >>>>>>>> 'custom' >>>>>>>> feature >>>>>>>> >>>>>>>> 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. >>>>>>> >>>>>>> This is exactly what Eli has explained Gendai and Dan today. >>>>> >>>>> (I was asking here because I did not understand the verbal >>>>> explanation.) >>>>> >>>>>> >>>>>> This is taken from the Stable Device Address design in >>>>>> http://wiki.ovirt.org/wiki/Features/Design/StableDeviceAddresses >>>>>> >>>>>> Unmanaged Device >>>>>> ----------------- >>>>>> Unmanaged Device will be supported in the new format and will >>>>>> include all unhandled devices as sound/controller/etc and >>>>>> future >>>>>> devices. Those devices will be persistent and will have Type , >>>>>> SubType (device specific) and an Address. For 3.1 an unmanaged >>>>>> Device is not exposed to any GUI/REST API. Unmanaged devices >>>>>> are >>>>>> passed to vdsm inside a Custom property. VDSM in it turn is >>>>>> passing this as is for possible hook processing. >>>>> >>>>> Thanks for the elaboration. Too bad that I've missed this issue >>>>> before. >>>>> >>>>> Are you aware of any hook making use of this? I hope that hook >>>>> writers >>>>> are not using APIs that are not documented in vdsmd(8). >>>>> >>>>> It seems as a classic case where a generic bag interface is >>>>> coerced >>>>> into >>>>> an awkward partially-documented interface. >>>>> >>>>> I think that a better approach would have been to pass all >>>>> devices >>>>> (managed and unmanaged alike) in the 'devices' property, and >>>>> let >>>>> vdsm >>>>> expose whatever is needed to the before_vm_start hook. >>>>> >>>>> Maybe we can still do this. >>>> >>>> That was the original idea but Ayal objected and I think Igor did >>>> not >>>> like it as well... >>>> >>> >>> +2. >>> The original design had an 'unmanaged' (or generic) device type, >>> and all >>> devices should have been normalized. But as explained, this was >>> strongly >>> rejected in the VDSM side, causing Eli write some special handling >>> for this anomaly. >> >> Can someone (Ayal?) explain the rejection on Vdsm side? >> Hiding part of the API in the custom propery bag requires strong >> reasoning indeed. > > It's not hiding anything. > Today vdsm passes the libvirt xml to the hooks + the custom properties. > If you pass 'non-managed devices' through the devices API then > basically you're saying to vdsm 'here is a bunch of things I want you > to ignore but be a sport and pass it on to the hooks'. > Last I checked, that mechanism is custom properties. I don't see any > reason to add another one. 1. this means hooks don't actually get the unmanaged devices today?

2. custom property are to pass parameters to the hook user can reasonably control. device management should not be part of that if not strictly related to the hook (from user's side).

3. I'm guessing (didn't get this first time i read your answer), you are hinting the unmanaged devices should be passed as a custom property to vdsm, auto generated by engine?