This is a request to extend libvirt documentation, explaining how is it possible to change a floppy/CDROM/usb-stick content for a running VM from host.
The VirDomainUpdateDeviceFlags function documentation states:
Change a virtual device on a domain, using the flags parameter to control how the device is changed. VIR_DOMAIN_DEVICE_MODIFY_CURRENT specifies that the device change is made based on current domain state.VIR_DOMAIN_DEVICE_MODIFY_LIVE specifies that the device shall be changed on the active domain instance only and is not added to the persisted domain configuration. VIR_DOMAIN_DEVICE_MODIFY_CONFIG specifies that the device shall be changed on the persisted domain configuration only. Note that the target hypervisor must return an error if unable to satisfy flags. E.g. the hypervisor driver will return failure if LIVE is specified but it only supports modifying the persisted device allocation. This method is used for actions such changing CDROM/Floppy device media, altering the graphics configuration such as password, reconfiguring the NIC device backend connectivity, etc.
It would be really nice if you could provide an example of usage of this command. Thanks to eblake on #virt who pointed me to this:
You could easily extract an example of use from there.