On Thu, 7 Jan 2021 17:43:54 +0100 Erik Skultety <eskultet@xxxxxxxxxx> wrote: > > > > 4.Define a mdev device with the uuid specified, but the mdev device > > defined seems using another uuid. Maybe it make a little confusion > > about the use of uuid in the xml: > > #cat mdev.xml > > <device> > > <name>mdev_85531b6d_e5e4_41c1_aa2a_8844717f066a</name> **** > > Yeah, the easy way out here is to document that the <name> element is > read only, but that would be wrong, because we allow specifying it > for domains, networks, interfaces, etc. So, we should give the end > user the option to specify whatever name they want and generate one > if none is provided. > Unfortunately, this appears to be difficult to achieve for persistent devices. For mediated devices, we are using mdevctl as our backend persistent device definition storage. But mdevctl doesn't provide a way to attach additional metadata along with a mdev definition. So we would need to either modify mdevctl to allow us to store additional data with a device definition, or we would need to create (and keep synchronized) a separate persistent storage for libvirt-specific metadata about mediated devices. It's also worth noting that 'nodedev-create' previously allowed you to create vHBA devices in libvirt, but the 'name' element is explicitly ignored (see https://wiki.libvirt.org/page/NPIV_in_libvirt): "NOTE: If you specify "name" for the vHBA, then it will be ignored. The kernel will automatically pick the next SCSI host name in sequence not already used." That said, I do think that it will be useful or even necessary to be able to create mdevs with a specific UUID, but I think that's a separate issue than being able to specify the 'name' of the nodedev. It seems better to do that by specifying a 'uuid' element within the mdev caps, rather than trying to parse a UUID from an arbitrary name string. For example: <device> <capability type='mdev'> <type id='i915-GVTg_V5_8'/> <uuid>901891a6-2077-4476-9465-53d8995b81b4</uuid> </capability> <parent>pci_0000_00_02_0</parent> </device> Thoughts? Jonathon
