[...] > >> So, just for clarification of the concept, the device with ^this UUID will have > >> had to be defined by the nodedev API by the time we start to edit the domain > >> XML in this manner in which case the only thing the autocreate=yes would do is > >> to actually create the mdev according to the nodedev config, right? Continuing > >> with that thought, if UUID doesn't refer to any of the inactive configs it will > >> be an error I suppose? What about the fact that only one vgpu type can live on > >> the GPU? even if you can successfully identify a device using the UUID in this > >> way, you'll still face the problem, that other types might be currently > >> occupying the GPU and need to be torn down first, will this be automated as > >> well in what you suggest? I assume not. > > > > Technically we shouldn't need the node device to exist at the time we > > define the XML - only at the time we start the guest, does the node > > device have to exist. eg same way you list a virtual network as the > > source of a guest NIC, but that virtual network doesn't have to actually > > have been defined & started until the guest starts. > > > > If there are constraints that a pGPU can only support a certain combination > > of vGPUs at any single point in time, doesn't the kernel already enforce > > that when you try to create the vGPU in sysfs. IOW, we merely need to try > > to create the vGPU, and if the kernel mdev driver doesn't allow you to mix > > that with the other vGPUs that already exist, then we'd just report an > > error from virNodeDeviceCreate, and that'd get propagated back as the > > error for the virDomainCreate call. > > > >> > >>> </source> > >>> </hostdev> > >>> </devices> > >>> > >>> In the QEMU driver, then the only change required is > >>> > >>> if (def->autocreate) > >>> virNodeDeviceCreate(dev) > >> > >> Aha, so if a device gets torn down on shutdown, we won't face the problem with > >> some other devices being active, all of them will have to be in the inactive > >> state because they got torn down during the last shutdown - that would work. > > > > I'm not sure what the relationship with other active devices is relevant > > here. The virNodeDevicePtr we're accesing here is a single vGPU - if other > > running guests have further vGPUs on the same pGPU, that's not really > > relevant. Each vGPU is created/deleted as required. > > I think he's talking about devices that were previously used by other > domains that are no longer active. Since they're also automatically > destroyed, they're not a problem. Yes, that was exactly my point, anyhow, seems like I got a grasp of Dan's proposal then, great. Erik -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
