Help on method updateDeviceFlags in module libvirt:

updateDeviceFlags(xml, flags=0) method of libvirt.virDomain instance
    Change a virtual device on a domain, using the flags parameter
    to control how the device is changed.  VIR_DOMAIN_AFFECT_CURRENT
    specifies that the device change is made based on current domain
    state.  VIR_DOMAIN_AFFECT_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_AFFECT_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.