Re: [libvirt] [PATCH 3/5] qemu: add usb-bot support from disks points of view

On 09/03/2013 08:06 AM, Gerd Hoffmann wrote: There is another case where hot-plug/unplug of a group of devices would be useful - if you want to hotplug/unplug a pci passthrough device using vfio *and* that device is a part of an iommu group that contains other devices *and* you're okay with having those other devices assigned to the guest as well *AND* you want to use "managed='yes'" (where libvirt automatically unbinds the devices from the host driver and binds them to vfio-pci before passing them off to the guest), then you need to be able to plug and unplug all the devices in that iommu group in a single operation, otherwise the plug fails (due to attempting to assign one device in a group when the other devices haven't been bound to vfio-pci or pci-stub). As it stands now you can only hot-plug/unplug with vfio if a device is in an iommu group all by itself, or if you don't use managed='yes', and instead deal with binding the devices to vfio-pci manually. If none of that makes sense, consider yourself lucky :-)